Cell Structure and Function PDF

EPPERIMENT 4 Dr. RASHA AL-AZAIZEH 1 Copyright © 2010 Pearson Education, Inc.  General Rules:  Cytology: Is the study of cellular structure and function. The major tools of cytologists are: ...

EPPERIMENT 4 Dr. RASHA AL-AZAIZEH 1 Copyright © 2010 Pearson Education, Inc.  General Rules:  Cytology: Is the study of cellular structure and function. The major tools of cytologists are:  Light microscopy.  Electron microscopy.  Cell chemistry.  Cell: Is the structural, functional, and biological unit for all living organisms. The Cell is the fundamental unit of life because it is:  The Smallest unit  Capable of performing all life functioning  Replicate independently Copyright © 2010 Pearson Education, Inc. 2  MODERN CELL THEORY: The basic principle of this theory are: 1. All known living things are made up of one or more cells 2. All living cells arise from pre-existing cells by division 3. The cell is the fundamental unit of structure and function in all living organisms. 4. The activity of an organism depends on the total activity of independent cells. 5. Energy flow (metabolism and biochemistry) occurs within cells Copyright © 2010 Pearson Education, Inc. 3  6. Cells contain DNA which is found specifically in the chromosome and RNA found in the cell nucleus and cytoplasm. 7. All cells are basically the same in chemical composition in organisms of similar species. Copyright © 2010 Pearson Education, Inc. 4  Cell categories: Unicellular organisms Two domains: Prokaryotes  Bacteria  Archaea (Live in extreme habitats) Cell Unicellular organisms: Protozoa Eukaryotes Multicellular organisms: Animals, Plants, Fungi and Algae Copyright © 2010 Pearson Education, Inc. 5 Copyright © 2010 Pearson Education, Inc. 6  Comparison Between Prokaryotic and Eukaryotic Cells Characteristic Prokaryotes Eukaryotes Size of cell Small (Typically 0.1-5.0 µm Large (Typically 10-100 µm in in diameter)* diameter)* Nucleus No nuclear membrane True nucleus, consisting of (envelope) or nucleoli (The nuclear membrane & nucleoli area of genetic material called nucleoid) Membrane- Absent* Present; examples include enclosed Organelles suspended in lysosomes, Golgi complex, organelles cytoplasm endoplasmic reticulum, mitochondria & chloroplasts Flagella Consist of two protein Complex; consist of multiple building blocks microtubules Cell wall Usually present; chemically When present, complex (typical bacterial chemically simple cell wall includes peptidoglycan) Copyright © 2010 Pearson Education, Inc. 7  Comparison Between Prokaryotic and Eukaryotic Cells Characteristic Prokaryotes Eukaryotes Plasma No carbohydrates and Sterols and carbohydrates membrane generally lacks sterols that serve as receptors present Cytoplasm No cytoskeleton or Cytoskeleton; cytoplasmic cytoplasmic streaming streaming Ribosomes Smaller size (70S) Larger size (80S); smaller size (70S) in organelles Chromosome Single circular Multiple linear (DNA)arrangement chromosome; lacks chromosomes with histones histones Cell division Binary fission Mitosis or Meiosis Reproduction Asexual; or transfer of Asexual or Sexual DNA fragments only (conjugation) Level of Unicellular Unicellular or Multicellular organization Copyright © 2010 Pearson Education, Inc. 8 Fundamental structure of the cells: All cells share in having  Plasma membrane  Cytosol  Genetic material (Chromosome & DNA)  Ribosomes Cytosol Copyright © 2010 Pearson Education, Inc. 9  Example of Prokaryotes Cyanobacteria:  The largest prokaryotes, formerly called blue-green algae.  They contain chlorophyll a and accessory pigments for photosynthesis.  Such as Oscillatoria Gloeocapsa Bacteria:  Its smaller than cyanobacteria.  Don’t have chlorophyll.  Such as bacteria found in yogurt (Lactobacillus). Copyright © 2010 Pearson Education, Inc. 10  The Bacteria Shapes: Copyright © 2010 Pearson Education, Inc. 11  The Structure of Bacteria Cell Envelope includes:  Plasma membrane: lipid bilayer with imbedded and peripheral Protein  Cell wall: maintains the shape of the cell and is strengthened by peptidoglycan  Glycocalyx: layer of polysaccharides on the outside of the cell wall and well organized and resistant to removal (capsule) Copyright © 2010 Pearson Education, Inc. 12  Eukaryotic Cells: Domain Eukarya includes:  Protists: 1. Amoeba: Have (pseudopodia) to movement and surround food, (contractile vacuole) to get rid of waste. 2. Paramecium: Movement by Cilia 3. Spirogyra: Filamentous green alga  Fungi  Plants  Animals Copyright © 2010 Pearson Education, Inc. 13  Eukaryotic Cells: Unicellular Amoeba Spirogyra cell Copyright © 2010 Pearson Education, Inc. 14 Copyright © 2010 Pearson Education, Inc. 15  Plant Cell Anatomy Copyright © 2010 Pearson Education, Inc. 16  Difference between Animal and Plant cells Copyright © 2010 Pearson Education, Inc. 17  Animal cells Plant cells Cell wall Absent Present (formed of cellulose) Shape Irregular ( indefinite ) Fixed ( definite ) shape shape Vacuole One or more small One, large central vacuole vacuoles (much taking up to 90% of cell smaller than plant volume. cells) Centrioles Present in all animal Only present in lower plant cells forms (e.g. chlamydomonas) Chloroplast Absent Present Plastids Absent Present Cell wall Absent Present Flagella Present in some cells Present in some cells (e.g. ( e.g. mammalian sperm of bryophytes) sperm cells) Cilia Present Most plant cells do not contain cilia. Lysosomes Lysosomes occur in Lysosomes usually not cytoplasm. evident. Plasmadesmata Copyright © 2010 Pearson Education, Inc. Absent Present 18  Organelle Eukaryotic Cells Two classes of organelles:  Endomembrane system:  Organelles that communicate with one another via membrane channels or via small vesicles Consists of: ⚫ Nuclear envelope ⚫ Membranes of endoplasmic reticulum ⚫ Golgi apparatus ⚫ Vesicles  Energy related organelles:  Mitochondria & chloroplasts  Basically independent & self-sufficient Copyright © 2010 Pearson Education, Inc. 19  Nucleus:  Separated from cytoplasm by nuclear envelope  Consists of double layer of membrane  Nuclear pores permit exchange between nucleoplasm & cytoplasm  Contains chromatin in semifluid nucleoplasm  Chromatin contains DNA of genes, and proteins  Condenses to form chromosomes  Chromosomes are formed during cell division  Dark nucleolus composed of rRNA  Produces subunits of ribosomes Copyright © 2010 Pearson Education, Inc. 20  Ribosomes:  The organelle responsible for protein synthesis in the cell  Composed of rRNA  Consists of a large subunit and a small subunit  Ribosomes located:  On the rough endoplasmic reticulum  Free in the cytoplasm, either singly or in groups, called polyribosomes Copyright © 2010 Pearson Education, Inc. 21  Endoplasmic Reticulum: A network of membranes inside a cell through which proteins and other molecules move and continuous with the outer membrane of the nuclear envelope. Type of Endoplasmic Reticulum: Rough ER:  Studded with ribosomes  Synthesizes and modifies proteins  Adds sugar to protein to form glycoproteins Smooth ER  Not bond with ribosomes  Synthesis of lipids  Site of various synthetic processes, detoxification, and storage  Forms transport vesicles Copyright © 2010 Pearson Education, Inc. 22  Golgi apparatus: A cell organelle that helps process and package proteins and lipid molecules, especially proteins destined to be exported from the cell. Copyright © 2010 Pearson Education, Inc. 23  Lysosomes:  Membrane-enclosed organelles that produced by the Golgi apparatus.  Contain powerful digestive enzymes and are highly acidic:  Digestion of large molecules such as proteins, nucleic acids, carbohydrates, and lipids to recycling of cellular resources  Apoptosis (programmed cell death) Copyright © 2010 Pearson Education, Inc. 24  Mitochondria structure  Contain ribosomes and their own DNA  Produce most of ATP utilized by the cell by cellular respiration Copyright © 2010 Pearson Education, Inc. 25  Plastid: Photosynthesis Copyright © 2010 Pearson Education, Inc. 26  Practical Part: Preparation of the wet mount for  Epidermis of Elodea plant: (Iodine or 0.1% Neutral red) to see the cell structure (Janus Green B + 7% sucrose to see mitochondria)  Potato (Iodine to see amyloplasts)  Yogurt: ( drop of water to see lactobacillus bacteria)  Onion Epidermal cells: (Iodine or 0.1% Neutral red) to see the cell structure (Janus Green B + 7% sucrose to see mitochondria)  Cheek epithelium: (Methylene blue) Copyright © 2010 Pearson Education, Inc. 27  Wet mount slide of onion epidermal cells Copyright © 2010 Pearson Education, Inc. 28  Wet mount slide of Geranium leaf (Epidermal cells) Copyright © 2010 Pearson Education, Inc. 29  Wet mount slide of cheek epithelium Copyright © 2010 Pearson Education, Inc. 30