GENBIO-1-Quarter-1-2024-2025 (1).pdf

Level: SENIOR HIGH SCHOOL Semester: FIRST Subject Group: SPECIALIZED SUBJECT (STEM) Quarter: FIRST Course Description: This subject is designed to enhance the understanding of the principles and concepts in the study of biology, particularly life processes at the cellular and molecular levels. It also covers the transformation of energy in organisms. Course Requirements and Calendar of Activities: Below is the list of activities that must be completed and submitted with their corresponding percentage. Date of Raw Final WEEK ACTIVITIES Completion Score Grade 1 Enabling Assessment Activity 1 – The Cell and 30 the Organelles 2 Performance Check 1 – Cell Types and 50 Tissues 3 Performance Check 2 – Cell Modification in 50 Real Life 4 Performance Check 3 – The Cell Cycle 50 5 Enabling Assessment Activity 2 – Gatekeeper 30 of the Cell 6 Performance Check 4 – Egg Osmosis 50 Experiment 7 Enabling Assessment Activity 3 -Enzyme and 30 Deficiencies 8 Enabling Assessment Activity 4 – Factors 30 Affecting Enzymatic Activity TOTAL 320 Grading System (General Biology 1) QUARTER 1 Performance Check 50% Enabling Assessment Activity 30% Quarterly Examination 20% FIRST QUARTERLY GRADE TOTAL 100% 1 LESSON 1 - THE CELL Learning Materials: Module, pen, paper, biology books, internet (if applicable) Prerequisite Content-knowledge: Definition of cell Prerequisite Skill: Describe the characteristics of cells Identify the parts of a cell INTRODUCTION: A. TIME ALLOTMENT: 4 hours B. CONSULTATION: For questions and clarifications, you may consult your subject teacher on the assigned schedule via face-to-face, FB messenger, or mobile number. C. RUA: At the end of the lesson, you should be able to: Explain the postulates of the cell theory; and Describe the structure and function of major and subcellular organelles. D. INSTITUTIONAL VALUES: Critical Thinking and Scientific Literacy E. OVERVIEW OF THE LESSON This unit will discuss the events that led to the concept of the cell theory, postulates of the cell theory, and the different structures of the cell and their functions. STUDENT’S EXPERIENTIAL LEARNING CHUNK 1: THE CELL All forms of life, except viruses, consist of cells. By definition, a cell is the fundamental and structural unit of all living organisms. It is the smallest biological, structural, and functional unit of all plants and animals. Therefore, the cell is the basic unit of life. Living things that are made up of only one cell, such as bacteria and protozoa, are called unicellular organisms, whereas those that are made up of many cells, such as plants and animals, are called multicellular organisms. Cells perform many different functions within a living organism such as digestion, respiration, reproduction, etc. Within the human body, a lot of cells give rise to a tissue → multiple tissues make up an organ → many organs create an organ system → several organ systems functioning together make up the human body. 2 CHUNK 2: DISCOVERY OF THE CELL Around the late 16th century, the first compound microscope (Fig. 2) was invented by Zacharias Janssen, a Dutch spectacle-maker, with help from his father. The discovery of the microscope made it possible to observe cells and even study them in detail. The first person to discover the cell, Robert Hooke (1635-1703), did so using a crude compound microscope and an illumination system Hooke designed in his role as curator of experiments for the Royal Society of London. Hooke discovered plant cells when he examined a thin slice of cork through the lens of his converted compound microscope. He saw a plethora of microscopic compartments that, to him, resembled the same structures found in honeycombs. The openings reminded him of the small rooms, called cells, where monks lived. He called the structures ‘cells’, from the Latin word cellula, which means “small rooms.” He called them "cells," and the name stuck. Hooke published his findings in 1665 in his book, Microphagia, which included hand-sketched drawings of his observations. A few years later after Hooke’s discovery, a dutch scientist Antonie van Leeuwenhoek (1632-1705), a tradesman by day and a self-driven biology student, created a microscope with a much higher magnification than the microscope that Hooke used. Leeuwenhoek discovered bacteria, protists, sperm and blood cells, rotifers and microscopic nematodes, and other microscopic organisms. CHUNK 3: CELL THEORY A century passed before several improvements on the microscope were made. These latest microscopes were used by German botanist Matthias Jakob Schleiden (1804-1881) and German physiologist Theodor Schwann (1810-1882). Schleiden used one of the new microscopes to look at plant cells. Around the same time, Theodor Schwann, used a microscope to study animal cells. Schleiden and Schwann realized that plant and animal cells have similar features. Their research became the bases of the first two postulates of the cell theory. The last postulate was eventually proven by German pathologist Rudolf Ludwig Karl Virchow (1821-1902) in 1858. Virchow, upon studying how cells played a role in diseases at that time, noticed that the existence of diseases in the organs and tissues come from affected cells. From this, he deduced that new cells come from pre-existing cells. 3 Therefore, the three important points of the modified cell theory are as follows: 1. The cell is the basic functional and structural unit of all living organisms. 2. All living organisms are made up of cells. 3. All cells arise from pre-existing cells. The first two postulates support the idea that the cell is the foundation of life. All organisms have one or more cells. No organism can exist without a cell that will support the body processes that it needs to survive. CHUNK 4: CELL STRUCTURE AND FUNCTIONS All life processes (i.e., movement, respiration, sensitivity, growth, excretion, reproduction, and nutrition) that occur within an organism are supported by the cell. The cell contains different parts, called organelles, which carry out different functions. Some of these are featured in the figure below. Figure 9. Structure of animal cell Cell Membrane The cell is bound by the cell membrane. The cell membrane is composed of a phospholipid bilayer embedded with proteins and carbohydrates. It is semipermeable which allows only selective passage of organic molecules, ions, water, and oxygen into and out of the cell. Also, the proteins in the lipid bilayer allow the entry and exit of molecules that cannot easily pass through the phospholipid bilayer. On the other hand, cholesterol helps keep the phospholipid bilayer from becoming stiff, thus providing fluidity. Figure 10. Cell membrane Cytoplasm Enclosed within the cell membrane is the cytoplasm. It contains a gel-like substance called cytosol – a mix of water, dissolved substances, and structural proteins. However, it has a semi-solid consistency that comes from the proteins within it. This is where the molecules first pass through after entering or before exiting the cell membrane. Several organelles are found in the cytoplasm which is concerned with active cell 4 function and their presence or size may vary between different organisms and different tissues. This is also where most cellular processes take place including the processing of proteins, fats, and sugars (glucose). Membrane-Bound Organelles Membrane-bound organelles are surrounded by a plasma membrane to keep their internal fluids separate from the cytoplasm of the rest of the cell. The following organelles are membrane-bound: 1. Nucleus The nucleus is the primary director of cellular activity and inheritance. This is where your cell makes decisions about which genes will be more "expressed" and which genes will be "suppressed". The nucleus is surrounded by the double membrane, called the nuclear envelope, that appears in active contact with the endoplasmic reticulum and the cell membrane. Inside the nuclear envelope is the nucleoplasm. Within the nucleoplasm is a dark network of chromatin, a combination of deoxyribonucleic acid (DNA) and proteins, which during cell division become distinct bodies or chromosomes. Substances that move in and out of the nucleus pass through the envelope’s nuclear pores. Finally, the nucleus houses the nucleolus which helps your cells produce ribosomes and plays a role in the cell's stress response. 2. Endoplasmic Reticulum (ER) Endoplasmic reticulum is the manufacturing plant of the cell, and it is responsible for producing substances your cells need to grow. It is a cytoplasmic double-walled membrane folded in layers that forms a network of interconnected sacs called cisterna. In between its membranes is the lumen, or cisternal space. The membrane of the endoplasmic reticulum is connected to the nuclear envelope, runs through the cytoplasm, and may also extend into the cell membrane. When ribosomes are attached to the endoplasmic reticulum, it gives a rough appearance; hence it is called rough endoplasmic reticulum. In the RER, ribosomes work hard to help your cells produce the thousands and thousands of different proteins that your cells need to survive. When ribosomes are not present in the ER, their appearance is smooth and is thus called the smooth endoplasmic reticulum. Figure 12. Rough and smooth endoplasmic reticulum 3. Golgi Bodies Golgi bodies also consist of cisternae. It works closely with the ER; the proteins newly produced in the ER enters the lumen, which is the space inside the organelle. The Golgi bodies "package" the protein and then pinch off to become vesicles. The vesicle moves toward the cis face. The Golgi 5 bodies may modify the substances in the vesicle by putting “tags” so that the substances will be recognized and accepted in their respective destinations. Once ready, the vesicles containing the modified substances exit at the trans face. Figure 13. Golgi bodies 4. Mitochondria The mitochondria, called the powerhouse of the cell, are small bodies whose primary function is to provide cellular energy through respiration and oxidation. These are surrounded by a lipid bilayer. But the mitochondria have two membranes: outer membrane serves as its covering, and inner membrane that is closely folded in on itself to create the cristae which give more space to carry out chemical reactions and produce more fuel for the cell. Inside the cristae is the matrix that contains different enzymes. Figure 14. Mitochondrion 5. Lysosomes Lysosomes play a key role in processing proteins, fats, and other substances. They are small and highly acidic, which helps them function like the "stomach" of your cell. The lysosome has hydrolytic enzymes that help digest food, recycle old components of the cell, and kill invading microorganisms so they can be removed from the cell. The digested food and recycled components are released into the cytosol to be used by the cell. The indigestible food stays in the lysosomes, which eventually become the residual bodies that can be eliminated by exocytosis. Figure 15. Lysosome 6. Peroxisomes The peroxisome is a central part of the cell's metabolism. That is because peroxisomes help absorb nutrients within your cells and come packed with digestive enzymes to break them down. 6 Peroxisomes also contain and neutralize hydrogen peroxide – which could otherwise harm your DNA or cell membranes – to promote the long-term health of your cells. Non membrane-bound Organelles Non membrane-bound organelles are more solid structures that are not fluid-filled, so they have no need for a membrane. 1. Ribosomes Ribosomes are small particles made up of RNA and protein. They may be free floating in the cytoplasm, attached to the endoplasmic reticulum, or as a polyribosome (series of ribosomes attached to mRNA). It helps in the assembly of proteins in the cell and works with other parts of the cell to synthesize proteins. 2. Cytoskeleton The cytoskeleton is made up of structural proteins that are strong enough to support the cell, and that can even help the cell grow and move. The cytoskeleton is the reason eukaryotic cells can take on complex shapes without collapsing in on themselves. There are three major types of filaments that make up the eukaryotic cell cytoskeleton: a. Microtubules: These are the largest filaments in the cytoskeleton, and these are made of a protein called tubulin. Microtubules are extremely strong and resistant to compression, so they are key to keeping your cells in the proper shape. They also play a role in cell motility or mobility, and they also help transport material within the cell. b. Intermediate filaments: These medium-sized filaments are made of keratin. They work together with the microtubules to help maintain the cell's shape. c. Microfilaments are smallest class of filaments in the cytoskeleton, that are made of a protein called actin. Actin fibres can easily get shorter or longer depending what your cell needs. These are especially important for cytokinesis (when one cell splits into two at the end of mitosis) and plays a key role in cell transport and mobility. Figure 16. Cytoskeleton Other Cell Parts Cell Wall Plant cells have an outer cell wall compared to animal cells that simply have the plasma membrane. Unlike the cell membrane, which is relatively fluid, the cell wall is a rigid structure that helps maintain the shape of the cell. The exact makeup of the cell wall depends on what type of organism you're looking at. But they're generally made of polysaccharides, which are complex carbohydrates, as well as structural proteins for support. 7 The cell wall maintains the shape of the plant, protects the cell, and helps regulate the cell’s uptake of water. It helps plants stand up straight and stand up to environmental factors like wind. It also functions as a semi-permeable membrane, allowing certain substances to pass into and out of the cell. Figure 17. Cell wall Vacuole Plant cells contain at least one large vacuole to maintain the cell's shape, while animal vacuoles are smaller in size. In plants, the central vacuole fills up with water and dissolved substances, and it can become so large that it takes up three-quarters of the cell. It applies turgor pressure to the cell wall to help "inflate" the cell so that the plant can stand up straight. Animal cells have smaller vacuoles. Different vacuoles help store nutrients and waste products, so they stay organized within the cell. Figure 18. Vacuoles in plant and animal cells Chloroplast Chloroplasts are found in plant cells and some algae – but those that do put them to good use. Chloroplasts are the site of photosynthesis, the set of chemical reactions that help some organisms produce usable energy from sunlight and also help remove carbon dioxide from the atmosphere. Chloroplasts are packed with green pigments called chlorophyll, which capture certain wavelengths of light and set off the chemical reactions that make up photosynthesis. Look inside a chloroplast and you'll find pancake-like stacks of material called thylakoids, surrounded by open space (called the stroma). Each thylakoid has its own membrane – the thylakoid membrane – as well. Figure 19. Chloroplast Additional References: Cell Theory: https://www.youtube.com/watch?v=zk3vlhz1b6k Organelles of the Cell: https://www.youtube.com/watch?v=RKmaq7jPnY 8 ANSWER SHEET (Please submit this page after answering the activities. Do not return the entire module) Name: Section: LAST NAME, FIRST NAME MIDDLE INITIAL Enabling Assessment Activity No. 1: The Cell and the Organelles E NGAGEMENT Score: /20 Identify the organelles and their corresponding functions Name of the Organelles Function of the Organelles 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. ASSIMILATION Score: /10 How did the invention of the microscope revolutionize the study of cells and lead to the discovery of this fundamental unit of life? Explain your answer. 9 LESSON 2 – CELL TYPES Learning Materials: Module, pen, paper, biology books, internet (if applicable) Prerequisite Content-knowledge: Characteristics of Cell Prerequisite Skill: Identify parts of a cell INTRODUCTION: A. TIME ALLOTMENT: 4 hours B. CONSULTATION: For questions and clarifications, you may consult your subject teacher on the assigned schedule via face-to-face, FB messenger, mobile number. C. RUA: At the end of the lesson, you should be able to: Distinguish prokaryotic and eukaryotic cells according to their distinguishing features; and Classify different cell types (of plant/animal tissues) and specify the functions of each. D. INSTITUTIONAL VALUES: Critical Thinking and Scientific Literacy E. OVERVIEW OF THE LESSON While there are certainly smaller things inside the body than living cells, the individual cell, like a Lego block, remains a basic unit of structure and function in all living organisms. Some organisms contain only one cell while others are multicellular. In biology, there are two types of cells: prokaryotes and eukaryotes. In this module, it will discuss the difference between prokaryotes and eukaryotes, as well as the different types of cell. STUDENT’S EXPERIENTIAL LEARNING CHUNK 1: PROKARYOTIC AND EUKARYOTIC CELL Prokaryotes represents cells without a true nucleus. However, they have a nucleoid – a region that's dense with cellular DNA – but don't actually have a separate membrane-bound compartment like the nucleus. The size of the cell is usually 1-5 micrometers only. A prokaryotic cell has only a few organelles, but ribosomes are mostly seen. Cell division happens through binary fission, a type of asexual reproduction that produces two identical cells. 10 Eukaryotes on the other hand, have a nucleus inside the cell and bound within a separate membrane. The size of the eukaryotes is within 10-100 micrometers. Eukaryotic cells have DNA that is packaged and ordered in structural units. Eukaryotic cells also have organelles, which are membrane-bound structures found within the cell. All those organelles help eukaryotic cells carry out more complex functions. So, organisms with eukaryotic cells – like humans – are more complex than prokaryotic organisms, like bacteria Figure 1. Parts of prokaryotic and eukaryotic cell CHUNK 2: CELL TYPES Multicellular organisms such as plants and animals are very complex and highly organized. They start from a single cell, the fertilized egg produced from the union of egg and sperm cell. The fertilized egg undergoes a series of cell divisions, producing many cells that will eventually form the variety of tissues. Those tissues can make organs and organ systems, so the organism can function. Tissue is a group of same or similar cells that perform a specific function in the body. There are two major types of tissues: plant tissue and animal tissue. A. Plant Tissues Flowering plants can grow throughout their lifetime because of meristematic tissues. Meristematic tissues are undifferentiated tissues, capable of continuous cell division, which would eventually grow into the primary tissues in the body of the plant. The three kinds of primary plant tissues are: Figure 2. Different plant tissues 1. Epidermal tissues Epidermal tissues are tightly packed cells that covers the leaves, flowers, roots, and stems of plants. It forms a boundary between the plant and the external environment. The epidermis serves several functions: it protects against water loss, regulates gas exchange, secretes metabolic compounds, and (especially in roots) absorbs water and mineral nutrients. In roots, certain epidermal cells develop long, slender projections called root hairs. The root hairs increase the surface are of the root for absorption of water and minerals from the soil, as well as anchor the plant to various substrates. 11 Figure 3. Epidermal tissues Figure 4. Cross-section of leaf On the surfaces of stems, leaves, and reproductive organs, epidermal cells produce hairs called trichomes. These hair-like projections protect plants from too much sun and conserve moisture. In leaves, certain cell contains guard cells that are present in the lower epidermis of the leaves. They contain chloroplast and operate small opening called stoma. The stoma controls the passage of air and water through the leaves, allowing plants to move water and nutrients up from the soil. 2. Ground tissues form the bulk of flowering plants. Their function depends on the type of pigment they contain. The types of ground tissue are the following: a. Parenchyma plant tissue is comprised of thin-walled cells with very large central vacuoles. The turgor pressure of these vacuoles is elevated when they are full of water, which gives structure and support to the plant. This tissue is found in all parts of the plant, and makes up large portions of the leaves, stems, and roots. b. Sclerenchyma plant tissue is a structural tissue which dies, but the cell wall and structure remain. Sclerenchyma plant tissue forms long, connected fibers called sclereids that can extend throughout a plant to provide support and strength to various organs. This plant tissue is commonly found in stems, bark, and in the hard shells of some fruits and nuts, such as pears. c. Collenchyma plant tissue also provides support. Often, collenchyma plant tissue is seen in young plants, with a limited number of cells. As such, only a portion of the cell wall in these cells will be thickened for support. This plant tissue is usually found wherever there is new growth and the other structural cells have not set in yet. Figure 5. Different ground tissues 3. Vascular tissues transport water and nutrients within the plant as well as providing support. There are two types of vascular tissue: a. Xylem transport water and minerals from the roots to leaves. b. Phloem transports sucrose and other organic compounds, usually from leaves to roots. 12 Figure 6. Xylem vessel (left) and phloem vessel (right) B. Animal Tissues Figure 7. Different animal tissues 1. Epithelial tissues consist of tightly packed cells that are found in various organ systems, such as skin. These cells can also be found in linings of the airways and respiratory system, blood vessels, urinary tract, digestive tract and kidneys. Packed tightly in sheets, they create a barrier to the outside world and protect you. Cells that make up epithelial tissues can have distinct arrangements: a. Simple epithelial has only a single layer of cells and is classified according to the shape of the cells: i. Simple squamous cells are composed of flattened cells. Since they are thin, they are useful in areas that need to move molecules quickly through absorption or filtration. They line the alveoli or air sacs in the lungs, capillar endothelium, pleural cavity, pericardium and the peritoneum. The thinness and flatness of these cells make them more common in interior portions of the body because they are fragile. 13 ii. Simple cuboidal cells are composed of cube-shaped cells. They are thicker than simple squamous cells. However, they are also common in areas that need to secrete or absorb substances. They rely on active transport to accomplish this. You can find them in the lining of secretory ducts in the kidneys or glands. iii. Simple columnar cells resemble rectangular pillars. They are taller than simple cuboidal epithelium. Their main functions are to secrete mucus and enzymes or provide sensory input. These cells can absorb and secrete different substances. The digestive tract and the female reproductive tract have many simple columnar cells. iv. Pseudostratified cells are rectangular and have one layer, but they look like they have more layers. They allow for the secretion and absorption of substances like mucus and enzymes. You can find them in the trachea and upper respiratory tract. b. Stratified epithelium is made up of more than one layer of cell and regenerates quickly. They also provide protection. This type of epithelium is found in linings of the nose, esophagus, anal canal, and vagina. The skin is also lines with stratified squamous epithelium reinforced by keratin to give its strength. Figure 8. Epithelial tissues c. Glandular epithelium is a kind of epithelium which covers the glands of the body. Their main function is secretion. Both endocrine and exocrine glands produce their secretions through the glandular epithelium via special cells called goblet cells. Glandular epithelium can be found in the reproductive tract and helps in sexual functions by secreting lubricating fluid during sexual excitation. The glandular epithelium also lines the intestine where it helps in the absorption of nutrients. Thus, it aids in digestion. Figure 9. Glandular epithelium 2. Connective tissue is most abundant and widely distributed tissue in complex animals. It maintains the form of the body and its organs and provides cohesion and internal support. The principal cell of connective tissues is the fibroblast, an immature connective tissue cell that has not yet differentiated. This cell makes the fibers found in nearly all of the connective tissues. The matrix in connective tissues gives the tissue its 14 density. When a connective tissue has a high concentration of cells or fibers, it has a proportionally-less- dense matrix. a. Loose connective tissue has some fibroblasts and collagen fibers widely scattered in the matrix. The space between the formed elements of the tissue is filled with the matrix. Loose connective tissue is found around every blood vessel, helping to keep the vessel in place. The tissue is also found around and between most body organs. b. Fibrous connective tissue contains large amounts of collagen fibers and few matrix materials. The fibers are lined up in parallel. Fibrous connective tissues are found in areas of the body where stress occurs from all directions, such as the dermis of the skin. Regular fibrous connective tissue is found in tendons (which connect muscles to bones) and ligaments (which connect bones to bones). Figure 10. Loose connective tissue Figure 11. Fibrous connective tissue c. Cartilage is characterized by collagenous fibers embedded in chondroitin sulfate. Chondrocytes (mature cartilage cells) are the cells that secrete collagen and chondroitin sulfate and make the matrix and fibers of the tissue. A cartilage with few collagen and elastic fibers is hyaline cartilage. Hyaline cartilage is found at the ends of long bones, reducing friction and cushioning the articulations of these bones. Elastic cartilage has a large amount of elastic fibers, giving it tremendous flexibility. The ears of most vertebrate animals contain this cartilage, as do portions of the larynx, or voice box. In contrast, fibrocartilage contains a large amount of collagen fibers, giving the tissue tremendous strength. Figure 12. Cartilage d. Bone is a mineralized connective tissue made by bone-forming cells called osteoblasts which deposit collagen. The matrix of collagen is combined with calcium, magnesium, and phosphate ions to make the bone hard. Bone can be divided into two types: compact and spongy. Compact bone is found in the shaft (or diaphysis) of a long bone and the surface of the flat bones, while 15 spongy bone is found in the end (or epiphysis) of a long bone. Compact bone is organized into subunits called osteons. A blood vessel and a nerve are found in the center of the osteon. Spongy bone is made of tiny plates called trabeculae, which serve as struts, giving the spongy bone strength. Figure 13. Bone tissues e. Adipose tissue, or fat tissue, is composed of cells called adipocytes that collect and store fat in the form of triglycerides for energy metabolism. Adipose tissues additionally serve as insulation to help maintain body temperatures, allowing animals to be endothermic. They also function as cushioning against damage to body organs. Figure 14. Adipose tissues f. Blood has different components: 1) erythrocytes responsible for transporting oxygen to body tissues (RBC); 2) leukocytes involved in defending the body against both infectious disease and foreign materials (WBC); 16 3) platelets participate in the stages leading up to coagulation of the blood to stop bleeding through damaged blood vessels; and 4) lymphocytes that make antibodies tailored to the foreign antigens and control the production of those antibodies. The fluid portion of whole blood, its matrix, is commonly called plasma. Figure 15. Muscle tissues 3. Muscle tissues are composed of long cells called muscle fibers that allow the body to move voluntarily or involuntarily. Movement of muscles is a response to signals coming from nerve cells. In vertebrates, these muscles can be categorized into the following: a. Skeletal muscle is made up of long cylindrical muscle fibers. The fibers have alternating light and dark bands that give them a striated appearance. Skeletal muscle has multiple nuclei located at the periphery of the cell just inside the plasma membrane. Skeletal muscle is a voluntary muscle because it moves according to will. It is attached to the bones by tendon and creates movement when it contracts. b. Smooth muscle made up of spindle-shaped mononucleated cells which are involuntary. The smooth muscle has no striations. It is found in the walls of intestine, stomach, and other internal organs, in blood vessels and in the iris of the eyes. c. Cardiac muscle is found only in the heart. It has both features of skeletal muscle and smooth muscles. It is striated with intercalated disk for synchronized heart, but it is involuntary. 4. Nerve tissue is made up of specialized signaling cells called neurons and supporting cells called neuroglia. Neurons have three parts: cell body, dendrites, and an axon. The cell body holds the major portion of the cytoplasm that includes the nucleus and other organelles. A dendrite conducts signals toward the cell body while an axon conducts nerve impulses away from the cell body These neurons sense stimuli and transmit electrical signals throughout the animal body. On the other hand, neuroglia functions to support, nourish and protect neurons by engulfing bacterial and cellular debris Additional References: Prokaryotic and Eukaryotic Cells: https://www.youtube.com/watch?v=Pxujitlv8wc Cells and Tissues: https://www.youtube.com/watch?v=15k5fajCN_w 17 ANSWER SHEET (Please submit this page after answering the activities. Do not return the entire module) Name: Section: LAST NAME, FIRST NAME MIDDLE INITIAL Performance Check No. 1: Cell Types and Tissues ENGAGEMENT Score: /40 Indicate the tissues, organs and structures involved where the following organ system in the first column and their corresponding functions of the mentioned tissues, organs or structured. Tissues, organs and Organ System Function of the tissues, organs or structure structure involved 1. 1. Circulatory 2. 1. 2. Respiratory 2. 1. 3. Digestive 2. 1. 4. Nervous 2. 1. 5. Endocrine 2. 1. 6. Urinary 2. 1. 7. Immune 2. 1. 8. Reproductive 2. 1. 9. Skeletal 2. 1. 10. Muscular 2. ASSIMILATION Score: /10 Explain the main characteristics of prokaryotic cells and provide examples of organisms where they are commonly found. 18 LESSON 3 – CELL MODIFICATION Learning Materials: Module, pen, paper, biology books, internet (if applicable) Prerequisite Content-knowledge: Characteristics of Cell Prerequisite Skill: Identify the cell parts INTRODUCTION: A. TIME ALLOTMENT: 4 hours B. CONSULTATION: For questions and clarifications, you may consult your subject teacher on the assigned schedule via face-to-face, FB messenger, mobile number. C. RUA: At the end of the lesson, you should be able to describe some cell modifications that lead to adaptation to carry out specialized functions (e.g., microvilli, root hair). D. INSTITUTIONAL VALUES: Critical Thinking and Scientific Literacy E. OVERVIEW OF THE LESSON Features or structures of the cell that make them different from another type of cell and at the same time enable them to carry out unusual functions are called cell modifications. This commonly occurs in multicellular eukaryotes, where the opportunity for cell specialization arises. Cell modifications seen in plants and animals are discussed in this module. STUDENT’S EXPERIENTIAL LEARNING CHUNK 1: PLANT CELL MODIFICATIONS 1. Succulent leaves of century plant (Agave), aloes, sedums, and desert plants, which are thick and fleshy, store water to enable them to survive long periods of drought and semidesert conditions. 2. Tendrils (modified leaf petioles, veins, or stipules), growing in climbing plants like garden peas, bitter gourd, and cucumber, can coil around supports for anchorage. 3. Younger leaves of poinsettia are brightly colored to help in attracting pollinators. 19 4. Tubular or vase-shaped leaves of Pitcher plants secrete a fluid for digesting insects falling into their cavities. 5. Lateral roots of mangrove trees growing in swamps produce pneumatophores (upright conical growth) that aerate the submerged roots. 6. Adventitious roots (called brace or prop roots) that develop from the stem or even from the leaves, such as in pandan or corn, grow into the ground to help underground roots support the stem. ALOE TENDRILS POINSETTIA PITCHER PLANT PNEUMATOPHORES ADVENTITIOUS ROOTS CHUNK 2: ANIMAL CELL MODIFICATIONS 1. Microvilli are finger-like projections extending from the free surface of epithelial cells that increase the surface area across which substances are absorbed. 2. Fimbrae are finger-like extensions from the oviduct near the ovary that help to propel the released ova towards the fallopian tube. 3. Alveoli are microscopic, grapelike air sacs found at the tip of the bronchioles in the lungs that provide tremendous surface area for gas exchange during respiration. 4. Goblet cell is a glandular, modified simple columnar epithelial cell that secretes gel-forming mucins, the major component of mucus. You can find them in the intestines and respiratory system. Their mucus can protect the membranes. In addition, they can make antimicrobial proteins, cytokines and other substances that keep you healthy and contribute to the immune system. 5. Red blood cell is a biconcave disk-shaped cell that provides more surface area for gas exchange; absence of its nucleus in mature red blood cells gives more space for the hemoglobin. 6. White blood cell, also called leukocyte, contains enzymes and other proteins needed to protect the body against both infectious disease and foreign invaders. 20 7. Neuron is a specialized cell with three parts: dendrites, cell body, and axon, which facilitates transmission of nerve impulses to and from the brain and the spinal cord. 8. Sperm cell has lots of mitochondria that will produce the energy needed to propel its flagellum towards the egg cell during fertilization; and contains the enzyme needed to penetrate the thick membrane surrounding the egg and deliver its genetic material. 9. Cilia are projections that can move and sweep things. Although cilia look a little like microvilli, they are longer and thicker. You can find cilia in the lungs as they move dust and other particles by using rhythmic actions. When the cilia beat, they can move mucus or other substances along. They appear in the respiratory system or reproductive system. In women, they make up the lining of the fallopian tubes and help move the eggs. MICROVILLI FIMBRIAE ALVEOLI GOBLET CELL WHITE AND RED BLOOD CELL NEURON SPERM CELL CILIATED EPITHELIUM 21 ANSWER SHEET (Please submit this page after answering the activities. Do not return the entire module) Name: Section: LAST NAME, FIRST NAME MIDDLE INITIAL Performance Check No. 2: Cell Modification in Real Life ENGAGEMENT Score: /30 Complete the table below by thinking of an object or a thing that has certain similarities with a given cell modification either in structure or function or both. Explain the similarity between the cell part and the object. The first one is given as an example. Similarities between cell modification and object Cell Modification Objects mentioned Structure: They are both a slender circular threadlike coil. Example: Tendrils Spring Function: They are both providing support to the structure or objects. 1. Lateral roots 2. Tubular shape leaves 3. Adventitious roots 4. Microvilli 5. Fimbriae 6. Alveoli 7. Goblet cell 8. Red blood cell 9. White blood cell 10. Platelets 11. Neurons 12. Sperm cell 13. Cilia 14. Flagella 15. Pseudopods ASSIMILATION Score: /20 Explain the importance of the cell wall in plant cells and discuss how this modification provides support and protection to plant cells. 22 LESSON 4 – CELL CYCLE Learning Materials: Module, pen, paper, biology books, internet (if applicable) Prerequisite Content-knowledge: Phases of Cell Cycle Prerequisite Skill: Identify structures of the cell INTRODUCTION: A. TIME ALLOTMENT: 4 hours B. CONSULTATION: For questions and clarifications, you may consult your subject teacher on the assigned schedule via face-to-face, FB messenger, mobile number. C. RUA: At the end of the lesson, you should be able to: characterize the phases of the cell cycle and their control points; describe the stages of mitosis/meiosis given 2n=6; explain the significance or applications of mitosis/meiosis; and identify disorders and diseases that result from the malfunction of the cell during the cell cycle. D. INSTITUTIONAL VALUES: Critical Thinking and Scientific Literacy E. OVERVIEW OF THE LESSON As long as the cell is growing and dividing, the physical and metabolic activities of cells occur in a regular cycle and in a repetitive manner. This is called the cell cycle. In this lesson, we discuss different phases of the cell cycle. 23 STUDENT’S EXPERIENTIAL LEARNING CHUNK 1: CELL CYCLE The two phases of the cell cycle are the interphase (nondividing phase), which is the process in which a cell may double its entire content in preparation for cell division, and the M-phase (dividing phase), where the cell contents are distributed into daughter cells. The amount of time spent in each phase of the cell cycle is a characteristic of a particular cell. When a cell is about to divide, it grows larger, the number of organelles doubles, and the amount of DNA also doubles as replication of DNA takes place. All of these happen during interphase, where a typical cell spends most of its life. Interphase, which is typically the longest stage, consists of three stages: 1. G1, the first interval (or gap) of cell growth, before DNA replication 2. S, the time of synthesis (DNA replication) 3. G2, the second interval (or gap), when the cell prepares to divide. Figure 1. Cell Cycle G1 Phase G1 and G2 were named gap intervals because cells at these stages outwardly seem to be inactive, but they are not. Most cells in the G1 phase are busy undergoing metabolic activities including the synthesis of mRNA and proteins which are needed for chromosome replication. The nucleus, and cytoplasm are enlarging toward mature size. The cell increases in volume by imbibing water and nutrients and by building new protoplasm. Cytoplasmic organelles, such as endoplasmic reticula, the Golgi apparatus, ribosomes, mitochondria, and chloroplasts, are formed. Secretory and storage granules and cell wall materials are produced. S Phase After G1, cell enters S phase, where DNA is replicated. This means that there is twice the actual DNA now present in the cell. Each chromosome consists of two chromatids. However, the chromosomes will become visible only in prophase. 24 G2 Phase During G2 phase, the cell rapidly grows, and protein synthesis continues. The important organelles and other materials which will play an important role during cell division, are synthesized by the cell. An example of this organelle is a centriole which is replicated before the cell divides. Cells divide to give rise to new cells, and it is through cell division that the mechanism of genetic transmission could be explained. There are two types of cell division, namely mitosis and meiosis. In both cases, the cell goes through the G1, S and G2 phases of the interphase before undergoing cell division. CHUNK 2: MITOSIS Mitosis is undergone by the somatic (body) cell and germ cell. It is the process by which the nucleus divides to produce two nuclei (Figure 3). Mitosis results in two daughter cells that are genetically identical to each other and to the parental cell from which they came. This process can be subdivided into the following stages: early prophase, prophase, prometaphase, metaphase, anaphase, and telophase. Stages of Mitosis 1. Prophase In the nucleus, the chromosomes become visible as short and thick rods. They are longitudinally double, with each half called a chromatid. One of the two centrosomes move to the opposite side of the cell. The nucleoli and nuclear membrane are gone by late prophase. Microtubules of the bipolar spindle assemble and attach sister chromatids to opposite spindle poles. 2. Metaphase All the chromosomes are aligned at the center (metaphase plate) between the spindle poles. Microtubules attach each chromatid to one of the spindle poles and its sister chromatid to the opposite pole. The chromatids in each chromosome separate from each other except at the centromere. 3. Anaphase Each chromatid of a chromosome possesses its own centromere. Sister chromatids separate and become daughter chromosomes that move toward the spindle poles. Thus, each pole receives the same number and types of chromosomes as the parent cell. 4. Telophase The chromosomes reach the spindle pole and start to decondense to become indistinct chromatin. The chromosomes uncoil and assume their extended form during interphase. The nuclear membrane then forms around each daughter group and the spindle microtubules disappear. New plasma membrane may assemble between them. Cytokinesis A cell’s cytoplasm usually divides after mitosis. This process of division of cytoplasm is called cytokinesis. The process of cytoplasmic division, or cytokinesis differs among eukaryotes. In an animal cell, the plasma membrane sinks inward to form a thin indentation between the forming spindle poles called the cleavage furrow. The plasma membrane is dragged inward until the cytoplasm (and the cell) is pinched into two. In a plant cell, cytoplasmic division is achieved through the cell wall plate formation. The plate grows outward until its edges become attached to the plasma membrane and thus form a partition in the middle of the cytoplasm. In time, this plate develops into a primary wall that merges with the parent’s wall. At the end of division, each daughter cell becomes enclosed by its own plasma membrane and its own cell wall. 25 Figure 3. Mitosis Important Feature of Mitosis The most important feature of mitosis is that the chromosome number remains the same throughout successive cell divisions. There is chromosome duplication followed by cell division resulting in an exact and equal distribution of chromosomes to each daughter cell. The chromosomes make-up of the two daughter cells is identical to that of the parent cell making mitosis an equational division. CHUNK 3: MEIOSIS Meiosis is a nuclear division mechanism that occurs in reproductive cells, the egg cells and the sperm cells. It is a type of nuclear division that reduces the number of chromosomes from the diploid number (2n) to the haploid number (n). During sexual reproduction, gametes combine in fertilization to reconstitute the diploid complement found in parental cell. Meiosis occurs in two stages that equally distribute chromosomes into two new nuclei two times (Figure 3). Below are the stages of meiosis that starts with interphase and followed by two successive cell divisions: Interphase Meiosis I Meiosis II DNA is replicated Prophase I Prophase II Prior to meiosis I Metaphase I Metaphases II Anaphase I Anaphase II Telophase I Telophase II The nucleus of a diploid (2n) cell contains two sets of chromosomes, one from each parent cell. DNA replication takes place before meiosis 1 begins, so each one of the chromosomes consists of two sister chromatids. 26 Stages of Meiosis I (Reductional Division) The first meiotic division results in reducing the number of chromosomes (reduction division). In most cases, the division is accompanied by cytokinesis. 1. Prophase I It is subdivided into five substages (Figure 4): a. Leptonema – Replicated chromosomes have coiled and are already visible as long thin threads. The number of chromosomes present is the same as the number in the diploid cell. b. Zygonema – Homologue chromosomes begin to pair and twist around each other in a highly specific manner. The pairing is called synapsis. And because the pair consists of four chromatids it is referred to as a bivalent tetrad. c. Pachynema – Chromosomes become much shorter and thicker due to further coiling. A form of physical exchange between homologues takes place at specific regions. The process of physical exchange of a chromosome region is called crossing over. Through the mechanism of crossing- over, the parts of the homologous chromosomes are recombined (genetic recombination). d. Diplonema – The two pairs of sister chromatids begin to separate from each other. It is at this point where crossing-over is shown to have taken place. The area of contact between two non- sister chromatids, called chiasma, become evident. e. Diakinesis – The four chromatids of each tetrad are even more condensed and the chiasma often terminalize or move down the chromatids to the ends. This delays the separation of homologous chromosomes. In addition, the nucleoli disappear, and the nuclear membrane begins to break down. 2. Metaphase I At metaphase I, homologous chromosome pairs (bivalents) are aligned in the middle of the cell. The two chromosomes of each pair become joined to the spindle microtubules at the opposite sides of the cell. 3. Anaphase I In anaphase I, all of the homologous chromosomes separate and begin moving toward the spindle poles. 4. Telophase I During telophase I, a new nuclear membrane forms around each cluster of chromosomes as the DNA loosens up. The two nuclei have a single set of chromosomes, so they are haploid (n). Stages of Meiosis II (Equational Division) The events in the second mitotic division are quite similar to mitotic division. The difference lies, however, in the number of chromosomes that each daughter cell receives. While the original chromosome number is maintained in mitosis, the number is reduced to half in meiosis. 1. Prophase II The chromosomes condense and the spindle microtubules become attached to each sister chromatid as the nuclear membrane breaks up. 2. Metaphase II The chromosomes which are still duplicated, or with two molecules of DNA, are aligned in the middle of the cell. 27 3. Anaphase II In anaphase II, the sister chromatids of each chromosome are pulled apart and move toward the opposite sides of the cell. Each chromosome is now made up of one molecule of DNA. 4. Telophase II During telophase II, new nuclear membrane forms around each cluster of chromosomes as the DNA loosens. The cytoplasm often divides at this point to form four haploid (n) cells whose nuclei contain one set of (unduplicated) chromosomes. Figure 4. Meiosis Figure 5. Stages of Prophase I 28 Crossing Over and Recombination Crossing over is a process that involves an exchange of genetic material between non-sister chromatids of a bivalent, during meiosis I (Figure 5). When chromosomes condense in prophase I, each is drawn closer to its homologous partner, so that non-sister chromatids align along their length. This tight, parallel orientation facilitates crossing over, a process by which a chromosome and its homologous partner exchange corresponding genetic segments. Crossing over is a normal and frequent process in meiosis. It greatly contributes to variation among individuals that sexually reproduce by shuffling maternal and paternal genes. Thus, crossing over introduces new combinations of alleles in both members of a pair of homologous chromosomes, which results in novel combination of traits among offspring. Figure 6. Crossing over CHUNK 4: SIGNIFICANCE OF MITOSIS AND MEIOSIS SIGNIFICANCE OF MITOSIS 1. It ensures the equal distribution of nucleic material to each daughter cell, thus maintaining a constant genetic constitution from parent cell down through each generation of cells, the basis for the constancy of species. 2. It is the process of reproduction in unicellular organisms. 3. It is the means of growth and replacement in multicellular organisms. It allows growth and increase in the number of cells which is necessary to replace cells that are lost daily from the body of an organism, especially in the surfaces, and facilitate wound healing. 4. It makes the growth of the individual from a single fertilized egg, or zygote, to an individual containing billions or trillions of cells by repeated cell division, possible. 29 SIGNIFICANCE OF MEIOSIS 1. It reduces the number of chromosomes in gametes by half which allows them to unite during fertilization without increasing the normal number of chromosomes in an organism. This is important so that the basic characteristics of a certain species will be maintained constant through successive generations. Example: Human cells have 46 chromosomes, with the exception of sperm and egg, which contain only 23 chromosomes each. When a sperm cell fertilizes an egg, the 23 chromosomes from each sex cell combine to make a zygote, a new cell with 46 chromosomes. The zygote is the first cell in a new individual. 2. It gives rise to new chromosome combinations in the gametes produced through crossing over and independent assortment of homologous chromosomes. This genetic variation is essential for a species to be able to evolve and adapt in a changing environment. CHUNK 5: WHEN MITOSIS BECOMES PATHOLOGICAL Checkpoint genes controlling the cell cycle may mutate producing signaling proteins that may no longer function properly. As a result, the cell makes too much or too little of a checkpoint gene product. When enough of these checkpoint mechanisms fail to work, a cell loses control over its cell cycle. Thus, the cell may skip interphase, so division continues with no resting period. Signaling mechanism that makes abnormal cells die may stop working. Such mutations can be passed on along the cell’s descendants producing an accumulation of abnormally dividing cells called neoplasm. A neoplasm that forms as a lump in the body is called a tumor. The gene that helps transform a normal cell into a tumor cell is called an oncogene, which is a mutated gene. Some oncogene mutations can be passed onto offspring, which is a reason why some types of tumors tend to run in families. Tumor can be benign or malignant. Benign tumor grows very slowly, and their cells retain the adhesion proteins that keep them properly attached to their home tissue. An example of this is ordinary skin mole which is not dangerous. A malignant tumor, or cancer, however, becomes progressively worse and is dangerous to health. Malignant cells typically display the following characteristics: a) they grow and divide abnormally, and the number of small blood vessels that transport blood to the growing cell mass also increases abnormally, b) their plasma membrane has defective adhesion proteins; thus, malignant cells do not stay confined to their home tissue and c) they can break loose from their home tissue and invade other parts of the body by slipping into and out of the vessels of both circulatory and lymphatic systems. This characteristic is called metastasis. Cancer is on the rise in developing countries. Today 55% of new cases arise in developing countries – a figure that could reach 60% by 2020 and 70% by 2050. Some cancer – causing mutations can be inherited. Certain lifestyle choices such as not smoking and avoiding exposure of unprotected skin to sunlight can be reduce one’s risk of developing cancer. Some malignancies can be detected early with periodic screening such as Pap smear or dermatology exams. If detected early enough, may neoplasms can be treated before metastasis occurs. Additional Resources Cell Cycle: https://www.youtube.com/watch?v=_AtHhradflA Cell Cycle: https://www.genome.gov/genetics-glossary/Cell-Cycle#:~:text=A%20cell%20cycle%20is%20a,mitosis%2C% 20and%20completes%20its%20division. Cell Division of Meiosis and Mitosis: https://www.youtube.com/watch?v=A-mFPZLLbHI 30 ANSWER SHEET (Please submit this page after answering the activities. Do not return the entire module) Name: Section: LAST NAME, FIRST NAME MIDDLE INITIAL Performance Check No. 3: The Cell Cycle ENGAGEMENT Score: /40 Make a 3D model of the cell cycle that will showcase the different phases. You can use recyclable or indigenous materials that are present only in your home or community. Do it yourself creatively! Rubric for 3D Model Making Excellent Good Fair Needs Improvement Criteria (10) (8) (6) (4) Demonstrate Demonstrate full Demonstrate some Demonstrate little to advanced Concept understanding on the understanding on the no understanding on understanding on the Presentation concept about cell concept about cell the concept about concept about cell modification modification. cell modification modification Performs skills, Performs skills, Performs skills, Does not performs and/or express and/or express and/or express skills, and/or express Art Skills creativity at a high creativity at a creativity at a basic creativity at an level. proficient level level appropriate level Present single side Present sides of cell Present single side Present sides of cell of cell modification Work Quality modification neatly of cell modification neatly and with care. with little neatness or and with care. neatly and with care. care. All aspects of cell All aspects of cell All aspects of cell All aspects of cell division model are division are division are division are completed with no completed with 1 completed with 2-3 completed with 4-5 Accuracy mistakes. Structure / mistake in Structure mistakes in Structure mistakes in Structure chromosome pairing, and chromosome and chromosome and chromosome etc. are accurate. pairing, etc. pairing, etc. pairing, etc. TOTAL ASSIMILATION Score: /10 Explain the purpose and significance of meiosis in sexual reproduction. Discuss how meiosis ensures genetic diversity in offspring and why it is essential for the survival of a species. 31 LESSON 5 – STRUCTURE AND FUNCTION OF CELL MEMBRANE Learning Materials: Module, pen, paper, biology books, internet (if applicable) Prerequisite Content-knowledge: Function of cell membrane Prerequisite Skill: Explain the function of cell membrane INTRODUCTION: A. TIME ALLOTMENT: 4 hours B. CONSULTATION: For questions and clarifications, you may consult your subject teacher on the assigned schedule via face-to-face, FB messenger, mobile number. C. RUA: At the end of the lesson, you should be able to: Describe the structural components of the cell membrane; and Relate the structure and composition of the cell membrane to its function D. INSTITUTIONAL VALUES: Critical Thinking and Scientific Literacy E. OVERVIEW OF THE LESSON We introduce the different structures of the cell. In this lesson, we discuss the outermost structure of the cell, the cell membrane. STUDENT’S EXPERIENTIAL LEARNING CHUNK 1: STRUCTURE OF THE PLASMA MEMBRANE 32 Figure 1. The Plasma Membrane A cell membrane has been described as a fluid mosaic. The “mosaic” part is attributed to the mixed composition of the cell membrane, and the “fluid” part comes from the ability of the bilayer to drift sideways and spin around their long axis. This happens because the phospholipids in a typical membrane are not bonded to one another. A phospholipid is amphipathic, which means it has hydrophilic and hydrophobic ends. The hydrophilic head, made of a phosphate group, has affinity with water, whereas the hydrophobic tail, made up of fatty acid, does not. On the tail of the phospholipid is a kink. The kink is de to a double bond in the unsaturated fatty acid. The kink prevents the tight packing of the phospholipid, hence its fluid movement. Figure 2. Structure of a phospholipid Cholesterol is found in between the phospholipids. The cholesterol acts as a fluidity buffer. During warm temperatures, it makes the movement of phospholipids limited, making them less fluid. During low temperature, it prevents the close packing of the phospholipids thus increasing their fluidity. Phospholipids and cholesterol are important in maintaining the fluidity of the cell membrane. Failure of these two to function may have detrimental effects to the cell. For example, A cell is exposed to high temperature, and the phospholipids and cholesterol cannot keep the normal fluidity of the cell membrane. When this occurs, an electrolyte imbalance may result in the cell, which may eventually cause the cell to swell or cause certain organelles to have impaired functions. In the nerve cell, for example, the nervous function may become disabled if there is an electrolyte imbalance. Many types of proteins are associated with a cell membrane, and each type adds a specific function to it. Thus, a cell membrane can have different characteristics depending on the proteins present in it. The types of proteins that may be present in the cell membrane and the functions they carry out are as follows: 1. Channel proteins form a channel that allows a substance like hydrogen ions to follow across the inner mitochondrial membrane, a process needed for the synthesis of ATP. 2. Carrier proteins transport molecules by changing their shape to receive substances like sodium and potassium across the plasma membrane, an important step that makes possible conduction of nerve impulse. 3. Cell recognition proteins are glycoproteins that help the body to recognize invading pathogens and initiate immune response. 33 4. Receptor proteins have a shape that allows only a specific molecule, a signaling molecule, to blind to it. Such binding brings about a coordinated cellular response. For example, the liver stores glucose after it is signaled by insulin. 5. Enzymatic proteins are membrane proteins needed by the cell to carry out metabolic reactions and maintain homeostasis. 6. Junction proteins involved in forming various types of junctions, like gap junctions that allow signaling molecules to pass through and make ciliated cells lining the respiratory tract to beat in unison. FUNCTIONS OF THE PLASMA MEMBRANE Plasma membrane, which is selectively permeable, regulates the passage of molecules into and out of the cell. This function is important to maintain its normal composition under changing environment conditions. Substances that are hydrophobic and therefore similar to the phospholipid center of the membrane can easily diffuse across membranes without consuming energy. Polar molecules, which are chemically incompatible with the center of the membrane, require an expenditure of energy for their transport. In general, small, non-charged molecules such as carbon dioxide, oxygen, glycerol, and alcohol can freely cross the membrane since they can easily pass through the hydrophobic tails of the membrane because they are also nonpolar. Water, although a polar molecule, can readily cross the primarily nonpolar membrane because there are channel proteins called aquaporins that can transport it across the membrane. Ions, such as sodium and potassium, and polar molecules, such as glucose and amino acids, can slowly cross a membrane. But when assisted by specific carrier proteins that can recognize particular shapes of ions and molecules, they can move quickly across the membrane. This shows that the structure and composition of the plasma membrane allows it to regulate the passage of materials across it. Additional Resources Cell Membrane Structure, Function, and The Fluid Mosaic Model: https://www.youtube.com/watch?v=UxvFdW9aO0s 34 ANSWER SHEET (Please submit this page after answering the activities. Do not return the entire module) Name: Section: LAST NAME, FIRST NAME MIDDLE INITIAL Enabling Assessment Activity No. 2: Gatekeeper of the Cell ENGAGEMENT Score: /20 Answer the following questions to further understand the cell membrane and its structure and functions. Cell Membrane Parts Function of the Parts 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. ASSIMILATION Score: /10 Explain its role as the "gatekeeper" of the cell. How does the cell membrane control the movement of substances in and out of the cell? 35 What is the significance of transportation on your daily life, how about the transportation all the nutrient and vitamins to your body? Explain LESSON 6 – TRANSPORT MECHANISM Learning Materials: Module, pen, paper, biology books, internet (if applicable) Prerequisite Content-knowledge: Function of cell membrane Prerequisite Skill: Explain the function of cell membrane INTRODUCTION: A. TIME ALLOTMENT: 4 hours B. CONSULTATION: For questions and clarifications, you may consult your subject teacher on the assigned schedule via face-to-face, FB messenger, mobile number. C. RUA: At the end of the lesson, you should be able to: Explain transport mechanisms in cells (diffusion osmosis, facilitated transport, active transport); and Differentiate exocytosis and endocytosis D. INSTITUTIONAL VALUES: Critical Thinking and Scientific Literacy E. OVERVIEW OF THE LESSON Molecules and substances move in several ways that fall within two categories: passive transport and active transport. In passive transport, heat energy of the cellular environment provides all of the energy, hence, there is no energy-cost to the cell. Active transport, however, requires the cell to do work, requiring the cell to expend its energy reserves. STUDENT’S EXPERIENTIAL LEARNING CHUNK 1: PASSIVE TRANSPORT Simple Diffusion Diffusion is the natural tendency for molecules to move from a higher concentration to a lower concentration that is down their concentration gradient, until molecules are distributed equally (Fig. 1). Their movement is random and is due to the energy found in the individual molecules. For instance, when a crystal of dye is dropped in water, the molecules of both dye and water move in different directions, but their net 36 movement is toward the region with lower concentration. A solution is made up of both a solute, usually a solid and a solvent, usually a liquid. In this case, the solute is the dye, and the solvent is the water. Once the solute and the solvent are evenly distributed, their movement continues, but there is no net movement in either direction. Figure 1. Simple Diffusion. The speed of mixing between molecules depends on the following factors: 1. Size It takes more energy to move bigger molecules, thus, the smaller the size, the faster the rate of diffusion, the vice versa. 2. Temperature Molecules move faster at higher temperatures, making them collide more often. Thus, the faster the temperature, the faster the rate of diffusion. 3. Concentration Concentration gradient is the difference in solute concentration between adjacent regions of a solution. Solutes tend to diffuse “down” their concentration gradient, that is, from a region of higher concentration to one of lower concentration. As the concentration of a solution increases, the molecules become more crowded, and the collision between them becomes more often. Thus, during a given interval of time, more molecules are bumped out of a region of higher concentration than bumped into it. 4. Charge Charged particles of matter (ion or molecule) in a fluid add up to the fluid’s overall electrical charge. A difference in charge between two regions of the fluid can influence the rate and direction of diffusion between them. For example, positively-charge substances like sodium ions will tend to diffuse toward a region with an overall negative charge. 5. Pressure A change, or difference in pressure between two adjoining regions may affect the rate and direction of diffusion. Pressure squeezes molecules together, and the more crowded the molecules become, the more frequent molecules collide and rebound among them, thus, the faster the diffusion. Whenever a substance exists in greater concentration on one side of a semipermeable membrane, such as the cell membranes, any substance that can move down its concentration gradient across the membrane will do so (Fig. 2). Consider substances that can easily diffuse through the lipid bilayer of the cell membrane, such as the gases oxygen (O2) and carbon dioxide (CO2). Because cells rapidly use up oxygen during metabolism, there is typically a lower concentration of O 2 inside the cell than outside. As a result, oxygen will diffuse from the interstitial fluid directly through the lipid bilayer of the membrane and into the cytoplasm within the cell. On the other hand, because cells produce CO2 as a byproduct of metabolism, 37 CO2 concentrations rise within the cytoplasm; therefore, CO2 will move from the cell through the lipid bilayer and into the interstitial fluid, where its concentration is lower. This mechanism of molecules moving across a cell membrane from the side where they are more concentrated to the side where they are less concentrated is a form of passive transport. Figure 2. Simple Diffusion across the Cell Membrane. Osmosis Water also can move freely across the cell membrane of all cells, either through protein channels or by slipping between the lipid tails of the membrane itself. Osmosis is the diffusion of water through a semipermeable membrane (Fig. 3). Figure 3. Osmosis. The movement of water molecules is not itself regulated by cells, so it is important that cells are exposed to an environment in which the concentration of solutes outside of the cells (in the extracellular fluid) is equal to the concentration of solutes inside the cells (in the cytoplasm). Two solutions that have the same concentration of solutes are said to be isotonic. When cells and their extracellular environments are isotonic, the concentration of water molecules is the same outside and inside the cells, and the cells maintain their normal shape. Osmosis occurs when there is an imbalance of solutes outside of a cell versus inside the cell. A solution that has a higher concentration of solutes than another solution is said to be hypertonic, and water molecules tend to diffuse into a hypertonic solution (Fig. 4). Cells in a hypertonic solution will shrivel as water leaves the cell via osmosis. In contrast, a solution that has a lower concentration of solutes than another solution is said to be hypotonic, and water molecules tend to diffuse out of a hypotonic solution. Cells in a 38 hypotonic solution will take on too much water and swell, with the risk of eventually bursting. A critical aspect of homeostasis in living things is to create an internal environment in which all of the body’s cells are in an isotonic solution. Various organ systems, particularly the kidneys, work to maintain this homeostasis. Figure 4. Concentration of Solutions. Many cells are isotonic to the environment to avoid excessive inward and outward movement of water. When an animal cell such as a red blood cell is immersed in an isotonic solution, the cell gains water at the same rate that it loses it. The cell’s volume remains constant in this situation. When a red blood cell is immersed in a hypotonic solution, the cell gains water, swells, and may eventually burst due to excessive water intake. When placed in a hypertonic solution, an animal cell shrinks and can die due to water loss. Unlike animal cells, other cells must constantly export water from their interior to accommodate the natural inward movement. Most plants are hypotonic with respect to their immediate environment. Osmotic pressure within the cell pushes the cytoplasm against the cell wall and makes a plant cell rigid. A plant cell placed in an isotonic solution is flaccid and a plant wilts in this condition. In contrast with animal cell, a plant cell is turgid and healthy in a hypotonic solution. In a hypertonic solution, a plant cell loses water, shrivels, and its plasma membrane detaches from the cell wall. This situation eventually causes death in plant cells. Facilitated transport Large polar or ionic molecules, which are hydrophilic, cannot easily cross the phospholipid bilayer. Very small polar molecules, such as water, can cross via simple diffusion due to their small size. Charged atoms or molecules of any size cannot cross the cell membrane via simple diffusion as the charges are repelled by the hydrophobic tails in the interior of the phospholipid bilayer. Solutes dissolved in water on either side of the cell membrane will tend to diffuse down their concentration gradients, but because most substances cannot pass freely through the lipid bilayer of the cell membrane, their movement is restricted to protein channels and specialized transport mechanisms in the membrane. To control the entrance and exit of molecules, selective transport of materials is necessary. One simple process is facilitated diffusion that utilizes protein transmembrane channels that are specific to certain molecules. The solute simply binds to the transport protein and gets released to the other side of the membrane (Fig. 5). It is a passive process driven by the concentration of molecules both inside and the outside of the membrane. Passive transport protein moves substances from a region of higher concentration down their concentration gradient by: a) changing its shape when it binds to the molecule, like glucose, and then reverting to its original shape after releasing the molecules to the other side of the membrane; b) forming permanently open channel through a membrane: and c) forming gated channel that open and close in response to a stimulus such as binding to a signaling molecule or a shift in electrical charge. 39 Figure 5. Facilitated transport A common example of facilitated diffusion is the movement of glucose into the cell, where it is used to make ATP. Although glucose can be more concentrated outside of a cell, it cannot cross the lipid bilayer via simple diffusion because it is both large and polar. To resolve this, a specialized carrier protein called the glucose transporter will transfer glucose molecules into the cell to facilitate its inward diffusion. Figure 6. Active Transport. CHUNK 2: ACTIVE TRANSPORT Certain molecules are transported in and out of the cell, independent of concentration. This process requires the expenditure of energy in the form of ATP and is called active transport. In active transport, substances move against their concentration gradient, i.e., from lower concentration to one of higher concentration (Fig. 6). To make this possible, transport protein uses energy from ATP to pump a solute against its concentration gradient. Bulk/Vesicular Transport Other forms of active transport do not involve membrane carriers. This mode of transport involves movement of large particles, or even a virus through a vesicle that is formed when a patch of membrane bulges into the cytoplasm because the hydrophobic tails of the lipids in the bilayer are repelled by water on both sides (Fig. 8). There are two modes of transit: 1. Exocytosis involves the transport of substances in bulk outside of the cell. A vesicle formed from the endoplasmic reticulum moves to the cell surface. Its lipid bilayer membrane studded with proteins fuses with the plasma membrane, and then releases its contents to its surroundings. 2. Endocytosis involves the transport of substances in bulk into the interior of the cell. As the cell takes up substances in bulk near its outer surface, a small patch of plasma membrane balloons inward taking extracellular fluid with it. The balloon moves farther into the cytoplasm and then pinches off as a vesicle. The vesicle delivers its contents to an organelle or stores them in a cytoplasmic region. Endocytosis often brings materials into the cell that must be broken down or digested. Phagocytosis is an endocytosis of large particles. Many immune cells engage in phagocytosis of invading pathogens. In contrast to phagocytosis, pinocytosis brings fluid containing dissolved substances into a cell through membrane vesicles. 40 Figure 7. Types of Vesicular transport. Additional Resources Cell Membrane Transport - Transport Across A Membrane - How Do Things Move Across A Cell Membrane: https://www.youtube.com/watch?v=J5pWH1r3pgUs 41 ANSWER SHEET (Please submit this page after answering the activities. Do not return the entire module) Name: Section: LAST NAME, FIRST NAME MIDDLE INITIAL Performance Check No. 4: Transport Mechanism ENGAGEMENT Score: /40 Perform the following experiment below and answer the following guide question. OBJECTIVES: Learn about the phenomena of diffusion and equilibrium Explore the semi-permeable membrane of an egg MATERIALS: 4 large eggs 4 glasses (preferably wider rather than taller) White vinegar Water Blue food coloring (or another dark color) Corn Syrup Molasses Toothpick Tape measure (or a piece of string and ruler) Pen Paper Foil or plastic wrap (optional) PROCEDURE: Part 1: 1. Place each of the 4 eggs in a separate glass. 2. Pour vinegar inside each of the glasses so it completely covers each of the eggs. You may like to cover the glasses with foil or plastic wrap to reduce the smell in your cabinet or cool dry place. 3. Place the eggs inside the cabinet for approximately 24 hours. The vinegar will react with the eggshell eventually. Part 2: 1. Empty the vinegar out of each of the glasses and wash them thoroughly. 2. Lightly rinse each of the eggs with water. 3. Place the eggs back into the glasses. 4. Label each of the glasses 1 thru 4 and use the table provided at the end of this activity to keep track of the three different eggs. 5. Measure the weight of each egg and record the weight around for each egg using the table provided. 6. Cover one egg with water, one with water and a drop of blue food coloring, one with molasses, and one with corn syrup. 7. Place the eggs back inside the cabinet or cool dry place. You may also like to cover the glasses with plastic wrap or foil to lessen the smell. 8. Wait several hours (such as until the morning) to see what happens to the eggs! 42 Part 3: 1. Carefully remove the eggs from the substances and rinse them carefully with water. 2. Just as before, measure the weight of each egg and record the weight around for each egg using the table provided. 3. Finally, place the eggs back inside the glasses after they have been properly washed or place them in new cups or glasses. 4. Use a toothpick to carefully pop each of the membranes of the eggs. GUIDE QUESTIONS: 1. Answer the following table with the result of your experiment Mass before Mass before What was inside the Egg soaking in soaking in each Change in mass egg? vinegar (g) set-up (g) Egg: Water Egg: Water w/ food coloring Egg: Molasses Egg: Corn Syrup 2. What happen to the shell of the egg after soaking in vinegar after 24 hours? (5 pts) 3. Which of the following egg exhibits the characteristic of hypertonic, isotonic, hypotonic? Explain (4 pts) 4. Did any of the outside substance make it to the inside of the egg? (5 pts) 5. Why did the water molecules travel better inside the egg than in the syrup molecules? (5 pts) 6. What substance must pass through the shell and membrane in order for a chick to develop correctly? (5 pts) ASSIMILATION Score: /10 Explain the significance of osmosis in maintaining water balance within cells. What happens to a cell when it is placed in a hypertonic solution? a hypotonic solution? a isotonic solution? Explain your answer. 43 LESSON 7 - METABOLISM Learning Materials: Module, pen, paper, biology books, internet (if applicable) Prerequisite Content-knowledge: Function of Enzyme Prerequisite Skill: Identify the different process in the cell Explain how metabolism occurs INTRODUCTION: A. TIME ALLOTMENT: 4 hours B. CONSULTATION: For questions and clarifications, you may consult your subject teacher on the assigned schedule via face-to-face, FB messenger, mobile number. C. RUA: At the end of the lesson, you should be able to: Describe the components of an enzyme; and Explain oxidation/reduction reactions. D. INSTITUTIONAL VALUES: Critical Thinking and Scientific Literacy E. OVERVIEW OF THE LESSON Cells undergo various activities that are essential for the growth, movement, and survival of organisms. These activities include different chemical processes that involve a continuous supply and use of energy. Such processes are called metabolism. Cellular operations are accomplished through the biochemical reactions that take place within the cell. These reactions are switched on and off, or sped up and slowed down, depending on the immediate needs and overall functions of the cell. At any given time, the various reactions involved in building up and breaking down cellular components must be regulated in a coordinated manner. To achieve this balance, cells organize these reactions or processes into different types of enzyme-powered pathways. 44 STUDENT’S EXPERIENTIAL LEARNING CHUNK 1: DEFINITION OF METABOLISM Metabolism is a series of chemical reactions in the body that converts food into energy. In the process of food conversion, some forms of energy are released as by-product. Metabolism is important in maintaining the living state of the cells and thus, of the organism. It helps us maintain the characteristics of life-growth, reproduction, repair of damaged parts, and ability to respond to the environment. Metabolism can be conveniently divided into two types (Figure 1): catabolism and anabolism. Figure 1. A diagram showing the mechanism of the types of metabolism. Catabolism This process involves the breakdown of molecules to release energy. For example, foods contain biomolecules (carbohydrates, proteins, and lipids). In catabolic reactions, these biomolecules are broken down to release energy. This energy is either used immediately or stored for later use. Some common examples of catabolic reactions are the following: Breakdown of polysaccharides into monosaccharides to generate energy Breakdown of nucleic acids into nucleotides for transmitting genetic information Breakdown of proteins into amino acids, either to make new ones or to produce glucose in the blood Breakdown of food in the stomach for the nutrients to be absorbed into the blood vessels The energy released in catabolic reactions is stored in ATP to be used in anabolic reactions. Anabolism Anabolism means “building things or substances in the body.” This process requires and consumes energy to allow the building processes to proceed. In anabolic reactions, our bodies use simple chemicals and molecules to build a vast array of products and substances, such as biomolecules, so that they can serve important functions. Common examples of anabolic reactions include the following: Building proteins (large, complex molecules) from amino acids (simple molecules) Cell reproduction, where cells multiply to increases tissue (or organ) size Mineralization of bones from inorganic substances Production of hormones necessary for certain organs to perform their functions As mentioned, anabolism is fueled by catabolism. Large molecules are broken down into smaller parts, releasing several ATP molecules in the process. Many anabolic processes are powered using these ATP molecules. Anabolism and catabolism are both vital processes. Inside the human body, anabolism builds up substances. This building up is balanced by catabolism, which breaks down the substances. Outside the human body, a person must achieve and maintain an equal balance in everything that is taken in and excreted out of his/her body. Thus, metabolism is closely connected to nutrition and the availability of 45 nutrients. If something hinders effective metabolism, energy production may be affected, resulting in weakness and sickness. That is why we should maintain a healthy diet, so that the necessary nutrients will be available for metabolism to proceed. Aside from nutrition, other factors that may influence the metabolic processes in the body include age, gender, and weight. CHUNK 2: ENZYMES The chemical reactions that make up metabolism do not proceed by themselves. These reactions are switched on and off depending on the cells’ immediate needs and overall functions. The organized mechanism of regulating the metabolic pathways is powered by organic catalysts called enzymes. Catalysts are substances that speed up a reaction without being used up, destroyed, or incorporated into the end product. Enzymes allow reactions to occur under mild conditions, partly by eliminating nonspecific side reactions. They also participate in the reaction by providing an alternative reaction pathway. But unlike other substances, they do not undergo permanent changes until the end of the reaction. They are only limited to changing the rate of reaction. Components of an Enzyme Enzymes are highly selective. They catalyze specific reactions only. This specificity is due to their shapes. A typical enzyme is composed of a protein called an apoenzyme and a nonprotein called a cofactor (see Figure 3). An apoenzyme can be called a proenzyme when it is inactive, which means either it is not attached to any substrate, or the enzyme is in its original form. Most protein enzymes have intra-and intermolecular bonds that are in secondary or tertiary structures. The shape could be disrupted by changes in temperature and pH. When the required temperature and pH are not achieved, some of the contours of the enzyme are affected, which may hinder any catalytic activity. The cofactors, on the other hand, assist apoenzymes in their biological activities. Cofactors have different types and each type behaves in a different way. Metal ion activators are not permanently bound to the apoenzymes. They supply positive charges to the enzyme through covalent bonding. Examples of these metals include magnesium (Mg +2), zinc (Zn+2), manganese (Mn+2), sodium (Na+1), iron (Fe+2), potassium (K+1), and copper (Cu+2). These metals are the dietary minerals that are part of your daily nutritional requirement. Without these, some of the required catalytic reactions may not proceed. Coenzymes are organic molecules that usually come from the vitamins that you take in every day. Like the metal ion activators, they temporarily bind to apoenzymes. Prosthetic cofactor can be either metal ion or organic molecules. The only difference is that they bind the apoenzymes permanently. When the apoenzymes and the cofactors are bound, they form an enzyme complex called a holoenzyme. The holoenzyme now becomes active and ready for any catalytic reaction. Not all enzymes are proteins. Some enzymes are also made of RNA molecules. Examples of these are the ribozymes, which synthesize the proteins in the ribosomes of cells. Ribozymes undergo catabolism to help build protein chains during protein synthesis. Therefore, they are also called catalytic RNA. Chemical reactions happen in an orderly manner through a series of li

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