General Biology 1 Week 2 PDF

GENERAL BIOLOGY 1 WEEK 2 LESSON 1: THE DISCOVERY OF THE CELL Introduction of Cell Theory The Cell Theories LESSON 2: THE BASIC UNIT OF LIFE The Cell Membr...

GENERAL BIOLOGY 1 WEEK 2 LESSON 1: THE DISCOVERY OF THE CELL Introduction of Cell Theory The Cell Theories LESSON 2: THE BASIC UNIT OF LIFE The Cell Membrane The Cell Structure and Function Activity 1: CROSSWORD PUZZLE! Direction: Answer the crossword puzzle below with the help of the clues provided. C E L C L U M C E L C M E C N DEOXYRIBONUCLICACID LL LL YT OP L ASM RANE E U RIBO SO M E S LESSON 1: PROKARYOTIC VS EUKARYOTIC CELLS LESSON 2: UNDERSTANDING THE BASIC UNIT OF LIFE LESSON 3: CELL MODIFICATIONS WHAT FITS IN, FUNCTIONS RIGHT OBJECTIVES: a. Distinguish prokaryotic and eukaryotic cells according to their distinguishing features; b. Classify different cell types (of plant/animal tissues) and specify the function(s) of each; and c. Describe some cell modifications that lead to adaptation to carry out specialized functions (e.g., microvilli, root hair). LESSON 1: PROKARYOTIC VS EUKARYOTIC CELLS ❑Cells are generally divided into two major types depending on their structure; The prokaryotes and eukaryotes. ❑In terms of age, prokaryotes have been around a lot longer than their counterparts. They were originally the only type of cell for billions of years (the oldest records date them back to roughly 3.5 billion years ago), and ❑eukaryotes evolved from them roughly 2-3 billion years ago. ❑ The first cells to appear on Earth were prokaryotic cells. ❑ A prokaryote is an organism made of a single prokaryotic cell or cell with no true nucleus. ❑ The earliest prokaryotes may have arisen more than 2.5 billion years ago. Bacteria’s are prokaryotes. They are very small cells (1-10 mm in diameter) with a simple structure. Prokaryotes do not have a nucleus. This means that their DNA is not enclosed in a membrane inside the cell. Instead, prokaryotes have a single loop of circular DNA called nucleoids that floats in the cell’s cytoplasm, but they lack membrane-bound organelles. Protein-making bodies called ribosomes also form part of the cytoplasm. ❑ Like all cells, prokaryotes have a cell membrane. ❑ All prokaryotes also have a cell wall surrounding the cell membrane. ❑ Their cell wall is made up of peptidoglycan. The cell wall helps provide support and protection for the cell. ❑ Some prokaryotes are enclosed by an additional layer. This layer is called the capsule. The capsule has a sticky surface area, so it allows prokaryotes to cling to surfaces, such as your skin and your teeth. ❑ Prokaryotes reproduce asexually. ❑ Organisms belonging to the Kingdom Eubacteria and Kingdom Archaea, such as bacteria, blue-green algae, archaeans, and spirochetes, are examples of prokaryotes. ❑ In contrast, eukaryotic cells are more complex than prokaryotic cells. They are generally larger (10-100 mm in diameter) than prokaryotic cells. ❑ They all have a cell membrane, ribosomes, and DNA as prokaryotic cells do. ❑ However, the DNA of eukaryotic cells are double stranded arranged into chromosomes and does not float freely in the cytoplasm. Instead, it is found in the nucleus, an internal compartment bound by a cell membrane. The nucleus is one kind of organelle found in eukaryotic cells. ❑ Organelles are structures that perform specific functions. Most organelles are surrounded by a membrane. ❑ Some organelles have membranes that form channels which help transport substances from one part of the cell to another part of the cell. Eukaryotes are organisms made of one or more eukaryotic cells. The earliest eukaryotes, like the first prokaryotes, were single-celled organisms. They arose about 1 billion years later than the earliest prokaryotes. Later, multicellular eukaryotes arose. ❑ Every type of multicellular organism that exists is made up of eukaryotic cells. Eukaryotes reproduce sexually and/or asexually. Animal cells, plant cells, fungi, and protists are eukaryotes. All cells maybe classified into two basic-cell types, depending on their internal organization. Prokaryotic cells or prokaryotes lack a true nucleus, while eukaryotic cells or eukaryotes possess a new nucleus. Prokaryotes contain DNA arranged in a single circular structure called nucleid, but they lack membrane bound organelles. While eukaryotes, has a double stranded DNA arranged into chromosomes and its organelles are surrounded by membranes. Eukaryotes are more complex and are generally larger than prokaryotes. LESSON 2: UNDERSTANDING THE BASIC UNIT OF LIFE Did you know that some organisms are microscopic yet still successful to survive for millions of years? Some organisms are made up of only one cell and these are known as unicellular organisms. Other bigger organisms are so complex that they are made up of many different types of cells; they are known as multicellular organisms such as snake and coconut tree. Animal and Plant cells have many organelles in common but some organelles also have features that different in both. At the same time cells of the same kind group together to form tissue that perform specific function in the body of an organism You will learn the different cell types of plants and animals together with their specific functions they performed. The cells of living things are different. Most cells are specialized to performed one specific function. Groups of cells performing special life functions are called TISSUES. The following are some human cells and its functions: 1. Blood cells – red, white blood cells and platelets floating in liquid plasma 2. Nerve cells – also called neuron.Cells with fiber which conduct impulses. It consist of a cell body, axon and dendrites. 3. Skeletal muscle cells – also called striated muscle cells because of their striped appearance when viewed under a compound microscope. 4. Ova or egg cells sex cells – Female sex cells produced by the ovaries. 5. Sperm cells –Male sex cells produced by the testes. ❑ Tissues are group of similar cells which perform a definite functions. These are several kinds of tissues in animals: ANIMAL TISSUES: A. EPITHELIAL TISSUES. These are made up of closely-packed cells arranged in flat sheet. It forms lining of various cavities and tubes in the body such as lining of the small intestine which secretes digestive substances and absorbed products of digestion. This tissue is specialized to form the covering or lining of all internal and external body surface. Some has special functions of absorption, secretion, excretion, sensation and respiration. These are several kinds of tissues in animals:  ANIMAL TISSUES: B. CONNECTIVE TISSUES hold parts of the body together, such as bones. The long tough fiber that hold bones onto other bones are called ligaments, forming joints, while the tissues which hold muscle to bone are called tendons. Cartilage is another type of connective tissue, which has widely spaced cells. Blood is regarded as specialized form of connective tissue because it originates in the bones and has some fibers. Blood is compose of red blood cells, white blood cells and platelets These are several kinds of tissues in animals: ANIMAL TISSUES: C. MUSCLE TISSUES are for movement in animals. 1. Involuntary- muscles not under our conscious control. Example. The muscles in your stomach move even if we do not let them do so and the action cannot be stopped either. This type of muscle is also called visceral or smooth muscle. These are several kinds of tissues in animals: ANIMAL TISSUES: C. MUSCLE TISSUES are for movement in animals. 2. Voluntary muscle – made up of long fibers and they move our bones. It is striated in appearance. We can control them at will. Example. We can raise our legs if we wish. This type of muscle is called skeletal muscle, since they are attached to the bones. These are several kinds of tissues in animals:  ANIMAL TISSUES: C. MUSCLE TISSUES are for movement in animals. 3. Cardiac muscle is a special type of muscle that make up our heart. It is an involuntary muscle that is striated in appearance. These are several kinds of tissues in animals: ANIMAL TISSUES: D. Nerve tissues it carry electrical and chemical signals and impulses from the brain and central nervous system to the periphery, and vice versa. This tissues are made up of specialized cells called neurons. Brain, spinal cord and nerves are all composed of nerve tissue. These are several kinds of tissues in animals: ANIMAL TISSUES: Motor neurons/efferent  a. Accept nerve impulses from the Central Nervous System b. Transmit them to muscles or glands Sensory Neurons/ afferent a. Accept impulse from sensory receptors b. Transmit them to CNS Interneurons/association a. Convey nerve impulse between various parts of the CNS These are several kinds of tissues in plant: PLANT TISSUES: A. Meristematic tissues are tissues responsible for the production of new cells. It is compose of immature cells and regions of active in cell division. It have small, thin cell walls and rich in cytoplasm. Found in the growing tips of roots and stems. These are several kinds of tissues in animals: PLANT TISSUES: A. MERISTEMATIC tissues. Kinds of Meristems  Apical meristems. Found at the tips of stems and roots and are mainly responsible for the increase in length of stems and roots. Lateral meristems. Found in the sides or periphery of roots and stems. Responsible of the increase in width or diameter of stems or roots. These are several kinds of tissues in plants : PLANT TISSUES: B. Permanent tissues. These are composed of mature and differentiated cells. Cells of this tissue have lost their ability to divide and they have specialized structure to perform specific functions. These are derived from meristematic tissues. These are several kinds of tissues in plants : PLANT TISSUES: B. Permanent tissues. Kinds of Permanent Tissues Simple permanent tissue – consist of only one type of cells ( eg. Parenchyma) Complex permanent – consist of more than one type of cells ( eg. Xylem and phloem) These are several kinds of tissues in plants : PLANT TISSUES: B. Permanent tissues. SIMPLE PERMANENT TISSUES 1. Epidermis. This is an external tissue which consist of a single layer of living cells. It serves as the protective outer covering of the leaves, young roots and young stems. It produce cutin to protect plants against loss of water. These are several kinds of tissues in plants : PLANT TISSUES: B. Permanent tissues. SIMPLE PERMANENT TISSUES 2. Parenchyma. This is an internal tissue and consist of living cells with thin cell wall. Found in the soft parts of roots, stems, leaves and flowers. Most of the chlorophyll of leaves are in the cells of parenchyma tissue. It is where photosynthesis occurs. The functions of parenchyma of stems and roots is food manufacturing and food storage.  Ex. Fleshy tissues of fruits and vegetables. These are several kinds of tissues in plants PLANT TISSUES: B. Permanent tissues. SIMPLE PERMANENT TISSUES 3. Collenchyma. This is also an internal tissue. The collenchyma cells are structurally similar to parenchyma cells except that their walls are irregularly and compactly arranged. The collenchyma is a strengthening or supportive tissue and functions to store food. These are several kinds of tissues in plants PLANT TISSUES: B. Permanent tissues. SIMPLE PERMANENT TISSUES 4. Sclerenchyma. Also an internal tissue consist of thick-walled, dead cells. The cells have uniformly thick heavily lignified secondary walls. They function mainly for support. Plant fibers are sclerenchyma cells. Found also in stone cells of chico fruit and in seed coat of coconut shells. These are several kinds of tissues in plants: PLANT TISSUES: B. Permanent tissues. COMPLEX PERMANENT TISSUES Vascular tissues 1. Xylem – primarily functions for the transport of water and dissolved substances upward in the plant body. 2. Phloem – primary functions in the transport of organic material such as carbohydrates and amino acids.  LESSON 3: CELL MODIFICATIONS WHAT FITS IN, FUNCTIONS RIGHT You might be wondering if why cells undergo modification? As organisms felt the pressure of natural selection and attempted to colonize new territories, the need for advancements in both structure and function were necessary. They evolved with modified structures (evolution) or were created with the appropriate structures (creationism) to fit the environment. Advancements in structure and function created complex life supporting systems that are more versatile and allow the organisms’ greater freedom for colonization in fringe territories. The cell is the fundamental unit of life. For it to cater its other tasks and functions the cell has to undergo modification. Cell specialization (or modification or differentiation) is a process that occurs after cell division where the newly formed cells are structurally modified so that they can perform their function efficiently and effectively. Types and Examples of Cell Modifications  1. APICAL MODIFICATION A type of cell modification that is found on the apical surface of the cell. Types and Examples of Cell Modifications 1. APICAL MODIFICATION PSEUDOPODS These are temporary, irregular lobes formed by amoebas and some other eukaryotic cells. Bulge outward to move the cell in order to engulf the prey. Types and Examples of Cell Modifications  1. APICAL MODIFICATION CILIA AND FLAGELLA Cilia are usually short, hair - like Structures that move in waves Flagella are long whiplike structures Formed from microtubules Types and Examples of Cell Modifications  1. APICAL MODIFICATION VILLI AND MICROVILLI These are finger-like projections that arise from the epithelial layer in some organs. They help to increase surface area for faster and more efficient adsorption Microvilli are smaller projections They arise from the cell’s surface that also increase surface area allowing faster and more efficient absorption Types and Examples of Cell Modifications 1. APICAL MODIFICATION EXTRA-CELLULAR MATRIX (ECM) It is a compound secreted by the cell on its apical surface Cell wall is the extra cellular structure in plant cells that distinguishes them from animal cells Glycoprotein is the main ingredient of ECM in animal cells Types and Examples of Cell Modifications 2. LATERAL MODIFICATION A type of cell modification that is found on the basal surface of the cell. Types and Examples of Cell Modifications 2. LATERAL MODIFICATION Gap Junction It is also known as communicating junctions Closable channels that connect the cytoplasm of adjoining animal cells. Types and Examples of Cell Modifications 2. LATERAL MODIFICATION Tight Junction It acts as barriers that regulate the movement of water and solutes between epithelial layers It prevents leakage of the ECF Types and Examples of Cell Modifications 2. LATERAL MODIFICATION Adhering Junction It anchors junction on the lateral surface of the cell It is similar to the anchoring junction of the basal surface of the cell Types and Examples of Cell Modifications  2. BASAL MODIFICATION A type of modification that is found on the basal surface of the cell. Types and Examples of Cell Modifications 2. BASAL MODIFICATION Desmosomes/Hemidesmosomes The anchoring junction on the Basal surface of the cell Rivet-like links between cytoskeleton and Extracellular matrix components such as the basal lamina that underlie epithelia Primarily composed of keratin, integrins and cadherins Types and Examples of Cell Modifications The cell has three types of modification: namely apical modification, lateral modification and basal modification. Apical modification occurs at the top part of the cell. Examples of these are the microvilli, cilia, stereocilia and flagella. Lateral modification happens at the sides of the cell. The tight junction, adhering junction, gap junctions, desmosomes are the good example of it. Basal modification occurs at the bottom part of the cell. The basal folding and hemidesmosomes are the best examples of this type of modification. Types and Examples of Cell Modifications Other specialized modifications include the development of a nerve cells, muscle cells, red blood cells and sperm cells. In plants, some identified specialized cells include the root hairs and the guard cells. Specialized Animal Cell Animal cells are specialized in many ways. Red blood cells are specialized to transport oxygen. Cells specialized to produce proteins are found in the pancreas. Pancreatic cells also possess large number of other organelles needed for protein export, including a well-developed golgi apparatus and clusters of storage vacuoles loaded with enzymes. The human ability to move is the result of the specialized structure of muscle cells. Skeletal muscle cells are packed with fibers arranged in a tight, regular pattern. Specialized Plant Cell The guard cell is an example of a specialized plant cell. It monitors the plant internal condition, changing their shape according to those conditions.