ANPH 111 - Lecture 2 - Structure of the Cell

Structure of The Cell Dr. Nasir Abdul Latif Ph.D (Medicine)  By the end of the session, you should be able to:- 1.Name and describe the four concepts of the cell theory. 2.List four elements that make up the bulk of living matter. 3.Define a generalized cell. 4.Identify on a cel...

Structure of The Cell Dr. Nasir Abdul Latif Ph.D (Medicine)  By the end of the session, you should be able to:- 1.Name and describe the four concepts of the cell theory. 2.List four elements that make up the bulk of living matter. 3.Define a generalized cell. 4.Identify on a cell model or diagram, the three major cell  regions (nucleus, cytoplasm, and plasma membrane). 5.Identify organelles, and indicate Cells Cells are the structural units of all living things The human body has 50 to 100 trillion cells Overview of the Cellular  Basis of Life The Cell 1. TheoryA cell is the basic structural : and functional unit of living organisms 2.The activity of an organism depends on the collective activities of its cells  3.According to the principle of complementarity, the biochemical activities of cells are dictated by their structure (anatomy) which determines their function INTRODUCTION TO THE CELL CELLS are often called the microscopic building blocks of the body. They are active and dynamic, they continually grow and specialize, function, die, and replenish themselves, by the millions every second. The whole body contains about 37.2 trillion (37,200,000,000,000 cells, There are 226 different kinds !! 2 CELL DIVERSITY- INTERNAL  ORGANIZATION The Nucleus of each cell contains DNA (deoxyribonucleic acid) which directs the activity of the cell. *Eukaryotes are cells in animals and plants that contain a nucleus and membrane- bound organelles (small internal parts), which includes all of our body cells. *As a group, the Eukaryotes and the sex cells in our bodies are called Somatic cells. *Prokaryotes are cells that lack nuclei and membranebound inside parts, such as those in bacteria.  Anatomy of a Generalized Cell In general, a cell has three main regions or parts: 1.Plasma membrane 2.Nucleus 3.Cytoplasm  The Plasma Membrane Transparent barrier for cell contents Contains cell contents Separates cell contents from Fluid mosaic model is constructed surrounding environment. of: Two layers of phospholipids arranged “tail to tail” Cholesterol and proteins scattered among the phospholipids Sugar groups may be attached to  The Plasma Membrane Structure of the Plasma Membrane  The Plasma Membrane Phospholipid arrangement in the plasma membrane Hydrophilic (“water loving”) polar “heads” are oriented on the inner and outer surfaces of the membrane Hydrophobic (“water fearing”) nonpolar “tails” form the center (interior) of the membrane  This interior makes the plasma membrane relatively  The Plasma Membrane Role of proteins:- Responsible for specialized membrane functions: Enzymes  Receptors for hormones or other chemical messengers Transport as channels or Role of sugars: Glycoproteins are branched sugars attached to  The Plasma Membrane proteins that abut the extracellular space Glycocalyx is the fuzzy, sticky, sugar-rich area on the cell’s surface Structure of the Plasma Membrane The Plasma Membrane  The Plasma Membrane Cell membrane junctions Cells are bound together in three ways: 1.Glycoproteins in the glycocalyx act as an adhesive or cellular glue 2.Wavy contours of the membranes of adjacent cells fit together in a tongueand-groove fashion 3.Special cell membrane junctions are formed, which The Plasma Membrane Main types of cell junctions Tight junctions Impermeable junctions Bind cells together into leakproof sheets Plasma membranes fuse like a zipper to prevent  substances from passing through extracellular space between cells The Plasma Membrane Main types of cell junctions Desmosomes Anchoring junctions, like rivets, that  prevent cells from being pulled apart as a result of mechanical stress Created by buttonlike The Plasma Membrane Main types of cell junctions Gap junctions (communicating junctions)  Allow communication between cells Hollow cylinders of proteins (connexons) span the width of the abutting membranes Molecules can travel directly from one cell to the next through these  The Nucleus Control center of the cell Contains genetic material known as deoxyribonucleic acid, or D N A D N A is needed for building proteins D N A is necessary for cell 1.reproductionNuclear envelope Anatomy of the Generalized Animal Three regions:(membrane) 2.Nucleolus 3.Chromatin Cell Nucleus  Nucleus Structure: The nucleus is a sphere that contains another sphere called a nucleolus It’s function: the storage center of the cell’s DNA Manages cell functions The Nucleus Nuclear envelope (membrane) Consists of a double membrane that bounds the nucleus Contains nuclear pores that allow for exchange of  material with the rest of the cell Encloses the jellylike fluid called the Anatomy of the Generalized Animal Cell Nucleus  The Nucleus Nucleolus Nucleus contains one or more dark-staining nucleoli Sites of ribosome assembly Ribosomes migrate into the cytoplasm through nuclear  pores to serve as the site of protein Nucleolus  Inside nucleus Contains RNA to build proteins The Nucleus Chromatin  Composed of D N A wound around histones (proteins) Scattered throughout the nucleus and present when the cell is not dividing Condenses to form dense, rodlike bodies called chromosomes when the Anatomy of the Generalized Animal Cell Nucleus  The Cytoplasm The cellular material outside the nucleus and inside the plasma membrane Site of most cellular activities Includes cytosol, inclusions, and organelles  The Cytoplasm Three major component of the cytoplasm1.Cytosol: Fluid that suspends other elements and contains nutrients and electrolytes 2.Inclusions: Chemical substances, such as stored nutrients or cell products, that float in the cytosol 3.Organelles: Metabolic machinery  Structure of the Generalized of the cell that perform Many are membrane-bound, functions for the cellallowing for compartmentalization of Cell  The Cytoplasm Mitochondria “Powerhouses” of the cell Mitochondrial wall consists of a double membrane with cristae on the inner membrane Carry out reactions in which oxygen is used to Structure of the Generalized break down food into A T P molecules Cell  Mitochondria Produces energy through chemical reactions – breaking down fats & carbohydrates Controls level of water and other materials in cell Recycles and decomposes  The Cytoplasm Ribosomes Made of protein and ribosomal R N A Sites of protein synthesis in the cell Found at two locations: Free in the cytoplasm  Attached to the rough endoplasmic reticulum  The Cytoplasm Endoplasmic reticulum (E R) Fluid-filled tunnels (or canals) that carry substances within the cell Continuous with the nuclear membrane  Two types: Rough E R The Cytoplasm Endoplasmic reticulum (E R) Rough endoplasmic reticulum Studded with ribosomes  Synthesizes proteins Transport vesicles move proteins within cell Abundant in cells that make and export Synthesis and Export of a Protein by the Rough ER Synthesis and Export of a Protein by the Rough ER Synthesis and Export of a Protein by the Rough ER Synthesis and Export of a Protein by the Rough ER Synthesis and Export of a Protein by the Rough ER  The Cytoplasm Endoplasmic reticulum (E R) Smooth endoplasmic reticulum Lacks ribosomes Functions in lipid metabolism  Detoxification of drugs and pesticides The Cytoplasm Golgi apparatus Appears as a stack of flattened membranes associated with tiny vesicles Modifies and packages proteins arriving from the rough E R via transport vesicles  Produces different types of packages Secretory vesicles (pathway 1) Role of the Golgi Apparatus in Packaging the Products of the Rough ER  Golgi Bodies Protein 'packaging plant' Move materials within the cell  Move materials The Cytoplasm Lysosomes Membranous “bags” that contain digestive enzymes Enzymes can digest wornout or nonusable cell structures  House phagocytes that dispose of bacteria and cell debris  Lysosome Digestive 'plant' for proteins, fats, and carbohydrates Transports undigested material to cell membrane for removal  Cell breaks The Cytoplasm Peroxisomes Membranous sacs of oxidase enzymes Detoxify harmful substances such as alcohol and formaldehyde Break down free radicals (highly reactive chemicals)  Free radicals are converted to hydrogen peroxide and then to water The Cytoplasm Cytoskeleton Network of protein structures that extend throughout the cytoplasm  Provides the cell with an internal framework that determines cell shape, supports organelles, and provides the machinery for intracellular transport1.Microfilaments (largest) Three different types of elements 2.Intermediate filaments form the  Cytoskeletal Elements cytoskeleton:3.Microtubules (smallest) Support the Cell and Help to Generate Movement  The Cytoplasm Centrioles Rod-shaped bodies made of nine triplets of microtubules Generate microtubules  Direct the formation of mitotic spindle during cell division Cell Extensions Surface extensions found in some cells Cilia move materials across the cell surface Located in the respiratory system to move mucus  Flagella propel the cell The only flagellated cell in the human body is sperm Microvilli are tiny, fingerlike extensions of the plasma membrane Increase surface area for Cell Diversity The human body houses over 200 different cell types Cells vary in size,  shape, and function Cell shape reflects its specialized function Cell Diversity Cells that connect body parts Fibroblast  Secretes cable-like fibers Erythrocyte (red blood cell) Carries oxygen in the bloodstream  Cell Diversity Cells that cover and line body organs Epithelial cell Packs together in sheets Intermediate fibers resist tearing during rubbing or pulling  Cell Diversity Cells that move organs and body parts Skeletal muscle and smooth muscle cells  Cell Diversity Contractile filaments allow cells to shorten forcefully Cell that stores nutrients Fat cells  Cell Diversity Lipid droplets stored in cytoplasm Cell that fights disease  Cell Diversity White blood cells, such as the macrophage (a phagocytic cell) microorganisms  Cell Diversity Digests infectious  Cell Diversity Cell that gathers information and controls body functions Nerve cell (neuron) structures  Cell Diversity Receives and transmits messages to other body  Cell Diversity Cells of reproduction Oocyte (female) Largest cell in the body Divides to become an embryo upon fertilization Sperm (male) whip  Built for swimming to the egg for fertilization Flagellum acts as a motile THANK YOU