Cell Types and Cell Modification PDF

Cell Types and Cell Modification Module 4 Second Semester Task 1. Arrange the words according to the levels of biological organization.  There are certain characteristics that all living things exhibit, the characteristics of life. Living things are made up of cells. They metabolize, gro...

Cell Types and Cell Modification Module 4 Second Semester Task 1. Arrange the words according to the levels of biological organization.  There are certain characteristics that all living things exhibit, the characteristics of life. Living things are made up of cells. They metabolize, grow and develop, respond to stimulus, adapt to their environment and reproduce. Atom is smallest unit of matter, followed by molecules, which are combinations of atoms. When these molecules are grouped together, they ultimately form a cell.  The cell is the basic unit of life. In multicellular, organisms like plants and animals, cells are grouped as tissues to perform a specific function. Four Basic Types of Tissues 1. Epithelial tissue 2. Connective tissue 3. Muscle tissue 4. Nervous tissue  Epithelial Tissue It consists of closely packed sheets of cells covering surfaces- including the outside of the body- and cavities of the body wall. They are polarized which means they have both a top and a bottom face. The epithelial cell’s apical, top, side faces the inside of the cavity or the outside of a structure and is typically exposed to fluid or air.  Epithelial cells are closely packed, and this helps them to serve as barriers to fluid movement and potentially harmful microbes. Specialized junctions also connect the cells which bind them tightly together to prevent leakage. Other functions include secretion, filtration and protection. Cells that make up epithelial tissues can have distinct arrangements: cuboidal – secretion simple columnar – secretion and active absorption simple squamous – exchange of material through diffusion stratified squamous – protection pseudostratified columnar – lining or respiratory tract usually lined with cilia  Connective Tissue It is made up of cells that are suspended in an extracellular matrix. For most cases, protein fibers such as collagen and fibrin form the matrix in a solid, liquid or jellylike ground material. Connective tissue supports and, as the name implies, binds other tissues. The most abundant and widely distributed tissues that also functions as protection. The more common type of connective tissue is loose connective tissue.  This is located in the body, protecting organs and blood vessels and connecting epithelial tissues to the underlying muscles. Specialized types of connective tissue include adipose tissue- body fat, bone, cartilage and blood in which the extracellular matrix is liquid called plasma. Specialized Types of Connective Tissue BLOOD —made up of plasma (i.e., liquid extracellular matrix); contains water, salts, and dissolved proteins; erythrocytes that carry oxygen (RBC), leukocytes for defense (WBC), and platelets for blood clotting. 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 Specialized Types of Connective Tissue CARTILAGE —characterized by collagenous fibers embedded in chondroitin sulfate. Chondrocytes are the cells that secrete collagen and chondroitin sulfate. Cartilage functions as cushion between bones. BONE —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. Muscle Tissue Muscles cells, often referred to as muscle fibers contain actin and myosin proteins which allow them to contract. It is important in holding the body stable, enabling it to move and also pumping blood and pushing food through the digestive tract. There are three main muscle types: skeletal muscle, smooth muscle and cardiac muscle. Skeletal muscle, also striated-striped - muscle is what we refer to in daily life as muscle. The skeletal muscle is attached by tendons to the bones, which helps you to regulate your movements consciously.  Smooth muscle is found in blood vessel walls, digestive tract walls, uterus, urinary bladder and various other internal structures. Smooth muscle is not striated and its involuntary, not under conscious control. This means that you should not worry about transferring food into your digestive tract.  Cardiac muscle can only be seen in the walls of the heart. The cardiac muscle is striated like the skeletal muscle. Yet, it is not under voluntary supervision- you do not need to care about getting your heart going.  Nervous tissue It is involved in the collection and transmitting of information through detecting stimuli- external and internal signals. It is composed of two main cell types: neurons or nerve cells and glia. The neurons are the nervous system’s main functioning structure. They generate electrical signals called nerve impulses or action potentials which allow the neurons to transmit information very quickly over long distances. The glia serves mainly for promoting neuronal activity.  Dermal tissue It covers and protects the plant and monitors exchange of gases and absorption of water in roots. The stems’ and leaves’ dermal tissue is protected by a waxy cuticle that prevents loss of water by transpiration. Stomata are specialized pores that allow exchange of gas through cuticular holes. Like the stem and leaves, a waxy cuticle will not cover the root epidermis which would prevent water from being absorbed. Root hairs, which are root epidermal cell extensions, increase the root surface area, contributing significantly to the absorption of water and minerals.  Vascular tissue It transports water, minerals and sugars into different parts of the plant. Two different conducting tissues are made of vascular tissue: xylem and phloem. Xylem tissue brings water and nutrients from the roots to various parts of the plant and plays a role in stem structural support. Phloem tissue brings organic compounds from the photosynthesis site into other areas of the plant. The xylem and phloem often lie in a vascular bundle adjacent to one another.  Ground tissue It performs different functions depending on the type and position of the cells in the plant, including parenchyma (photosynthesis in the leaves and storage in the roots) collenchyma (shooting support in areas of active growth) sclerenchyma (shooting support in areas where growth has stopped) is the site of photosynthesis, provides supporting matrix for vascular tissue, provides structural stem support and helps store water and sugar.  CELL MODIFICATIONS THAT LEAD TO ADAPTATION Apical Modifications Microvilli. Also called brush/striated border. They are finger-like cytoplasmic extensions of the apical surface which increase surface area for absorption. Numerous and often regularly arranged and found in absorptive epithelia. Cilia. Appears as short hair-like structures or projections. The core is composed of microtubules arranged in specific manner and each cilium is connected to a basal body and extends from the free surface. Function is for movement/motility and it beats in coordinated rhythmical wave-like manner that promotes movement of materials over the surface. Flagella. They have the same axial structure with cilia but much longer that also functions with movement. Present in the tail of spermatozoa. Task 2. Crossword puzzle. Task 3. Identify the following: Task 4. POST-TEST Choose the letter of the best answer.