General Biology 1: Cell Types, Functions, and Modifications PDF

General Biology 1 CELL: TYPES, FUNCTIONS, AND MODIFICATION SHERWIN M. BERNABE Subject Teacher [email protected]  MOST ESSENTIAL LEARNING COMPETENCIES (MELCS) 3 4...

General Biology 1 CELL: TYPES, FUNCTIONS, AND MODIFICATION SHERWIN M. BERNABE Subject Teacher [email protected]  MOST ESSENTIAL LEARNING COMPETENCIES (MELCS) 3 4 5 STEM_BIO11/12-Ia-c-3 STEM_BIO11/12-Ia-c-4 STEM_BIO11/12-Ia-c-5 Distinguish Classify different cell Describe some cell prokaryotic and types (of plant/animal modifications that eukaryotic cells tissues) and specify lead to adaptation to according to their the functions of each carry out specialized distinguishing functions (e.g., features microvilli, root hair) INTRODUCTION Label Me PROKARYOTIC CELLS AND EUKARYOTIC CELLS. Cells are the basic structures of all living organisms. Every organism is composed of one or two structurally different types of cells: prokaryotic cells and eukaryotic cells.  PROKARYOTES Prokaryotes come from the Greek term pro meaning “before” and karyon meaning “kernel” referring to the nucleus. Prokaryotic cells have no nucleus, and their genetic material (DNA) is concentrated in a region called the nucleoid which does not have a membrane separating it from the rest of the cell. The major parts of a prokaryotic cell include cell wall, cell membrane, ribosomes, and a nucleoid.  PROKARYOTES Two domains of organisms comprise prokaryotes: Bacteria and Archaea. Bacteria make up most of the prokaryotes. In addition, Archaea are found in extreme environments such as hot springs or near volcanoes. The difference between Bacteria and Archaea is their type of cell wall: Archaea have a thicker cell wall that is very strong and protects it from the heat and chemicals found in harsh environments, while Bacteria have a more permeable cell wall that provides less protection from high temperatures or extreme pH, but takes less energy to build. PROKARYOTES PROKARYOTES  PROKARYOTES Both Bacteria and Archaea consist of unicellular organisms. Prokaryotes are important to all life on Earth for a number of reasons. They play a critical role in the recycling of nutrients by decomposing dead organisms and allowing their nutrients to be re-used. They are also important for many metabolic processes. Bacteria in our guts and mouth help with the digestion of food by breaking down difficult to digest carbohydrates and other compounds.  PROKARYOTES A prokaryotic cell is a simple, single-celled (unicellular) organism that lacks a nucleus, or any other membrane-bound organelle. We will shortly come to see that this is significantly different in eukaryotes. Prokaryotic DNA is found in the central part of the cell: a darkened region called the nucleoid. PROKARYOTIC CELL EUKARYOTES The oldest fossil evidence of eukaryotes is about 2 billion years old. Eukaryotes are combination of two Greek terms eu meaning “true” and karyon meaning “nucleus.” Thus, eukaryote means “true kernel” or “true nucleus,” alluding to the presence of the membrane-bound nucleus in these cells. The word organelle means “little organ,” and organelles have specialized cellular functions, just as the organs of your body have specialized functions. EUKARYOTES A cell has a membrane-bound nucleus and other membrane-bound compartments or sacs, called organelles, which have specialized functions. The major organelles found in a eukaryotic cell are cell membrane, cell wall, ribosomes, nucleus, mitochondria, endoplasmic reticulum, and lysosomes. They are both unicellular and multicellular eukaryotes. The four kingdoms of eukaryotic organisms are Kingdom Plantae, Kingdom Animalia, Kingdom Fungi, and Kingdom Protista. EUKARYOTES Plants are photosynthetic organisms containing cell walls and specialized reproductive tissue. Animals are organisms that lack cell walls, are capable of locomotion, and have a digestive tract. Fungi digest their food externally and then absorb it through their cell walls. Plants, animals, and fungi are all multicellular organisms. Protists are single-celled motile organisms that can be either photosynthetic or heterotrophic. EUKARYOTIC CELL ANIMAL CELLS Animals are capable of movement, although not all animals have muscles used for movement. In the most commonly encountered animals, the mobile stage is the adult, although some animals (such as corals and sponges) have sessile (or nonmobile) adult phases and mobile juvenile forms. Both animal and plant evolutionary history show the development of multicellularity and they move from water to land (as well as a secondary adaptation back to water, for example dolphins, whales, duckweed, and elodea). Animals developed external or internal skeletons to provide support, skin to prevent or lessen water loss, muscles that allowed them to move to search for food, brains and nervous systems for integration of stimuli, and internal digestive systems.  ANIMAL TISSUES ARE DIVIDED INTO FOUR MAIN TYPES: 1. Epithelial Tissue This type of tissue is commonly seen outside as coverings or as linings of organs and cavities. It is characterized by closely-joined cells with tight junctions. Being tightly packed, tight junctions serve as barriers for pathogens, mechanical injuries and fluid loss. Cells that make up epithelial tissues have distinct arrangements: cuboidal, simple columnar, simple squamous, stratified squamous, and pseudo-stratified columnar  EPITHELIAL TISSUES A. Cuboidal- for secretion B. Simple columnar- brick-shaped cells; for secretion and active absorption C. Simple squamous - plate-like cells; for exchange of material through diffusion D. Stratified squamous- multilayered and regenerates quickly for protection E. Pseudo-stratified columnar - single layer of cells; may just look stacked because of varying height; for lining of respiratory tract; usually lined with cilia (i.e., a type of cell modification that sweeps the mucus) EPITHELIAL TISSUES  ANIMAL TISSUES ARE DIVIDED INTO FOUR MAIN TYPES: 2. Connective Tissue These tissues are composed of the following: A. BLOOD- made up of plasma (i.e., liquid extracellular matrix): contains water, salts and dissolve proteins, erythrocytes that carry oxygen (RBC), leukocytes for defense (WBC), and platelets for blood clotting.  CONNECTIVE TISSUE B. CONNECTIVE TISSUE PROPER (CTP) Made up of loose connective tissue that is found in the skin and fibrous connective tissue that is made up of collagenous fibers found in tendons and ligaments. Adipose tissues are also examples of loose connective tissues that store fats which functions to insulate the body and store energy.  CONNECTIVE TISSUE C. CARTILAGE Characterized by collagenous fibers embedded in chondroitin sulfate. Chondrocytes are the cells that secrete collagen and chondroitin sulfate. Cartilage functions are cushion between bones.  CONNECTIVE TISSUE D. BONE Mineralized connective tissue made by bone-forming cells called osteoblasts which deposits collagen. Blood vessels and nerves are found at a central canal surrounded by concentric circles of osteon. CONNECTIVE TISSUES ANIMAL TISSUES ARE DIVIDED INTO FOUR MAIN TYPES: 3. Muscle Tissue These tissues are composed of long cells called muscle fibers that allow the body to move voluntary or involuntary. It gives rise to muscles' ability to contract. This is opposed to other components or tissues in muscle such as tendons or perimysium. It is formed during embryonic development through a process known as myogenesis. Muscle tissue consists of elongated cells also called as muscle fibers. This tissue is responsible for movements in our body. Movement of muscles is a response to signals coming from nerve cells.  MUSCLE TISSUE 3. Muscle Tissue In vertebrates, these muscles can be categorized into the following: A. Skeletal- striated: voluntary movements, attached to the skeleton B. Cardiac- striated with intercalated disk for synchronized heart contraction, involuntary, located in the walls of the heart C. Smooth- not striated; involuntary, located in walls of hollow visceral organs  ANIMAL TISSUES ARE DIVIDED INTO FOUR MAIN TYPES: 3. Muscle Tissue  ANIMAL TISSUES ARE DIVIDED INTO FOUR MAIN TYPES: 4. Nervous Tissue These tissues are composed of nerve cells called neuron and glial cells that function as support cells. These neurons sense stimuli and transmit electrical signals throughout the animal body. Neurons connect to other neuron that receives impulses from other neurons, while the axon is the part where the impulse is transmitted to other neurons.  NERVOUS TISSUE 4. Nervous Tissue  PLANT TISSUE Plant cells with similar structure and functions form plant tissue. Plant tissues come in several forms: vascular, epidermal, ground, and meristematic. Each type of tissue consists of different types of cells, has different functions, and is located in different places.  PLANT TISSUES ARE DIVIDED INTO TWO MAIN TYPES: 1. Meristematic tissue - is actively dividing to produce new cells. Meristematic tissue consists of undifferentiated small cell, with dense cytoplasm and large nuclei. The cells differentiate into new tissue of the plant. Meristematic tissue is found at the meristems of plants: A. Apical Meristem- are located at the growing points at the tips of roots and stems and results in an increase in the length of these structures.  MERISTEMATIC TISSUE B. Lateral Meristem Results in the growth in thickness or width of woody roots and stems. This tissue is also called cambium; cork cambium divides to form the cork cells that form the outer bark of a woody plant. Vascular cambium divides to make xylem and phloem tissue  PLANT TISSUES ARE DIVIDED INTO TWO MAIN TYPES: 2. Permanent Tissue These are specialized in function and do not divide constantly. Differentiation of cells begins as soon as cells have been formed by cell division, and results in changes in structure. There are three groups of permanent tissue:  PERMANENT TISSUE A. Epidermal Tissue a. Guard cells - are bean- shaped epidermal cells that occur on This is the outermost layer either side of a stoma- which is the opening that occurs on the of cells that covers the surface of a leaf. The guard cells roots, stems, and leaves. function to open and close the They are tightly packed, stoma, thus controlling the loss of water by transpiration. with no intercellular air spaces. The main function b. Hair cells - are formed by an of the epidermal cells is to extension of the cell wall. The hair functions to increase the surface protect the underlying area of the root to maximize the tissue from injury. uptake of water and nutrients. GUARD CELLS HAIR CELLS  PERMANENT TISSUE B. Vascular tissue a. Xylem Tissue- transport water and mineral salts from the ground water through the roots to the stems and Functions to leaves. It consists of vessels and tracheids- both cells have cell walls that transport and are strengthened with lignin and both support. types of cells are dead at maturity. b. Phloem Tissue- transport food from the leaves, where photosynthesis takes place, to areas undergoing growth or storage sites. Phloem tissue consists of long columns of sieve tubes and companion cells.  GROUND TISSUE This type of tissue forms the B. Collenchyma - thick body of the plant and is walled and alive at maturity responsible for support, storage, and photosynthesis. C. Sclerenchyma- thick walled and dead at There are three types of maturity ground tissue: A. Parenchyma - thin walled and alive at maturity; often multifaceted. GROUND TISSUE WHAT IS CELL MODIFICATION? Cell specialization or modification occurs after cell division wherein newly formed cells are structurally modified so that they can perform their function efficiently and effectively. APICAL MODIFICATION It is a cell modification found on the apical surface of the cell. Cilia and flagella Cilia are usually short, hair- like structures that move in waves. Flagella are long whip-like structures. Formed from microtubules APICAL MODIFICATION APICAL MODIFICATION Both cilia and flagella function for cell locomotion. APICAL MODIFICATION Villi and microvilli Villi are finger-like projections that arise from epithelial layer in some organs. They help to increase surface area allowing for faster and more efficient adsorption. Microvilli are smaller projections that arise from the cell’s surface that also increase surface area allowing faster and more efficient adsorption. APICAL MODIFICATION Structure of Microvilli These projections increase the surface area of the small intestine for the absorption of nutrients, and as a higher surface area = higher rate of transportation processes such as diffusion, they thus increase the rate of absorption. APICAL MODIFICATION Pseudopods Temporary, irregular lobes formed by amoebas and some other eukaryotic cells Bulge outward to move the cell or engulf prey From the Greek word pseudes and podos, meaning “false” and “feet”. APICAL MODIFICATION Extracellular matrix (ECM) Compound secreted by the cell on its apical surface Cell wall in the extracellular structure in plant cells that distinguishes them from animal cell Glycoprotein is the main ingredient of ECM in animal cells. They cover external surface, line up internal organs, take up nutrients, export wastes, and interact with the external environment. BASAL MODIFICATION Cell modification found on the basal surface of the cell desmosomes/hemidesmosomes 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, integrin, and cadherin. BASAL MODIFICATION LATERAL MODIFICATION A cell junction that provides contact between neighboring cells or between the cell and extracellular matrix. Tight Junction Acts as barriers that regulate the movement of the water and solutes between epithelial layers Prevent leakage of ECF LATERAL MODIFICATION Adhering Junction Anchoring junction on the lateral surface of the cell Very similar to the anchoring junction of the basal surface of the cell Fasten cells to one another LATERAL MODIFICATION Gap Junction Also known as communicating junctions Closable channel that connect the cytoplasm of adjoining animal cells Presence of connexon that allow direct exchange of chemical between the cytoplasm of the cells THANK YOU