Anatomy of the Cell PDF

FNAP0115 ANATOMY AND PHYSIOLOGY ANATOMY OF THE CELL HISTORY OF CELL THEORY: Robert Hooke- 1665 Anton Van Leeuwenhoek (Father of Mic...

FNAP0115 ANATOMY AND PHYSIOLOGY ANATOMY OF THE CELL HISTORY OF CELL THEORY: Robert Hooke- 1665 Anton Van Leeuwenhoek (Father of Microscopy)- 1675 Mattias Schleiden (1836) & Theodor Schwann (1839) Walter Sutton & Theodor Boveri – 1880 PRINCIPLES OF MODERN CELL THEORY: 1. Cells are the smallest complete living things. They are the basic unit of organization of all organisms. 2. All organisms are composed of 1 or more cells in which all life processes occur 3. Cells arise only from pre-existing cells through the process of cell division 4. All of today’s existing cells are descendants of the 1st cells formed early in the evolutionary history of life on earth. CELL - basic unit of biological organization of the human body - smallest unit of life 4 Elements of the Cell 1. Carbon 2. Oxygen 3. Hydrogen 4. Nitrogen Cells vary in: a. Size b. Shape c. Structure d. Function 3 MAIN REGIONS OF THE CELL 1. Nucleus - Located near the center surrounded by cytoplasm and cell membrane 2. Plasma Membrane/ Cell membrane - Covering of the cell 3. Cytoplasm Liquid portion of cell NUCLEUS - Headquarter or control center of cell - Contains genetic material called DNA which act as blueprint containing all instructions needed for building the entire body NUCLEAR MEMBRANE/NUCLEAR ENVELOPE - Double membrane barrier that separates nucleus from cytoplasm - Inner membrane surrounds and contains nucleoplasm & its materials - Outer membrane is continuous with the ER - Its pore functions for free transport or leakage of materials from nucleoplasm - Selectively permeable - Maintains the wholeness of the nucleus and controls passage of materials between nucleus and cytoplasm NUCLEOLUS - Spherical particle within the nucleoplasm that does not have a covering - Dense, non-membranous body composed of protein and RNA - Site where ribosomes are assembled - A cell may have one or more nucleolus CHROMATIN - Fine dark threads that appear in nucleus and is the genetic material of the cell - When cell is not dividing, its DNA is combined with protein and forms a loose network of bumpy threads called CHROMATIN - When cells are dividing, they shorten, thicken and becomes visible to form rod-like bodies called CHROMOSOMES - CHROMOSOMES are made up of DNA molecules and protein - Human body has 46 chromosomes (22 pairs autosomes, 1 pair sex chromosome) NUCLEOPLASM - Fluid medium of the nucleus - Made up of colloidal suspension of protein, nucleic acids, DNA, RNA, enzymes and other chemicals PLASMA MEMBRANE/ CELL MEMBRANE/PLASMALEMMA - Fragile, transparent barrier that contains the cell contents and separates it from the surrounding environment. - The membrane is composed of 2 lipid layer arranged “tail-tail” in which protein molecules float - Outer polar head of lollipop-shaped phospholipid molecules are hydrophilic (water-loving) and the inner non-polar tail is hydrophobic (water-hating) - Due to these properties in phospholipids, plasma membranes share a sandwich structure in which the polar head is exposed to water at the outside and inside of the cell, non-polar end face each other within the internal portion of the membrane. Such property allows plasma membrane to form by a process of self-assembly, and to repair itself when torn. - Lipid layer allows free passage of molecules through cell membrane via osmosis while protein acts as channels involved in transport (water and small water-soluble molecules can move), receptor sites for hormones (carrier that binds substances and move it through the membrane), others act as chemical messenger and identity markers for cell. - Branching sugar groups are attached to most of the proteins abutting the extracellular space. Such “sugar-proteins” are called glycoproteins, making the cell surface sticky (glycocalyx) - These glycoproteins determine blood type, and acts as receptors to certain bacteria, virus or toxin PLASMA MEMBRANE SPECIALIZATIONS Microvilli Membrane junctions a. Tight junction b. Desmosomes c. Gap junctions CYTOPLASM/ PROTOPLASM - Liquid portion of cell - Site of most cellular activities (factory area of the cell) - Main constituent is water CYTOPLASM- protoplasm outside of the nucleus NUCLEOPLASM- protoplasm inside of the nucleus 3 Major Elements of Cytoplasm: 1. Cytosol- semi-transparent fluid that suspends other elements 2. Organelles- metabolic machineries of the cell 3. Inclusions- chemical substances (lipid droplets, glycogen granules, melanin, mucus) MITOCHONDRIA - Power house of the cell - Tiny thread-like or sausage-shaped organelles composed of 2 membranes: Outer membrane gives- shape to the capsule Inner membrane provides a surface on which energy releasing-chemical reaction of cell occur. - ATP provides energy for cellular works RIBOSOMES - Actual sites of protein synthesis - Are tiny bi-lobed dark bodies made of protein and one variety of RNA called Ribosomal RNA - Some ribosomes float free in the cytoplasm where they manufacture proteins that function in cytoplasm while some are attached to membranes. ENDOPLASMIC RETICULUM - A network of interconnected membranes consisting of sacs and canals - Serves as mini-circulatory system for the cell because it serves as passageway of proteins synthesized by ribosomes. - 2 TYPES OF ER: - Rough ER/ Granular - Smooth ER/Agranular GOLGI APPARATUS/ GOLGI BODY - Considered to be the traffic director for cellular protein / packaging area of the cell - Flat sac-like cisternae that resembles stack of saucers - Major function is to modify and package proteins LYSOSOMES - Garbage collectors of the cell - Membranous bags containing powerful digestive enzymes - Function as demolition site because of its capacity to digest worn-out or non-usable cell structures and foreign substances that enter cell - Act as suicide agent in old & weakened cell. 3 General Functions of Lysosomes: a. Act in conjunction with stored food vacuoles b. Acts in the maintenance & repair of cellular components c. Acts as suicide agents in old & weakened cell AUTOLYSIS - Process where lysosomes expel all its enzymes directly into the cytoplasm to destroy cell & its organelles - Response to injury & infection - Generally does not occur in healthy cells APOPTOSIS - Programmed cell death - Intentional process that is highly regulated - Occur even in healthy cells CYTOSKELETON - Elaborate network of protein structures that extend throughout the cytoplasm - Acts as cell’s bones & muscles - Determines the shape, supports other organelles and provides machinery needed for intercellular transport and various types of cellular movements. Cytoskeleton is made up of: 1. Microtubules - determines overall shape of cell -very important in cell division 2. Microfilaments - actin/myosin - involved in cell motility & in producing changes in shape 3. Intermediate filaments - help form desmosomes and provide internal wire to resist pulling forces on the cell. CENTRIOLE - Rod-shaped bodies that lie at right angle to each other - Internally, they are made up of fine microtubules - Best known for their role in generating microtubules which determines shape of cell - during cell division, directs formation of mitotic spindle SPECIAL STRUCTURES: 1. Cilia 2. Flagella