Cell Structure and Function


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  • Within cells there is an intricate network of organelles that all have unique functions. These organelles allow the cell to function properly.
  • Cell Structure and Function

    1. 1. TOUR THE CELL
    2. 2. OVERVIEW: THE FUNDAMENTAL UNITS OF LIFE • All organisms are made of cells • The cell is the simplest unit of matter that is alive • Cell structure is correlated to cellular function (STRUCTURE DETERMINES FUNCTION!) • All cells are related by their descent from earlier cells (Pre-existing cells)
    3. 3. EUKARYOTIC CELLS HAVE INTERNAL MEMBRANES THAT COMPARTMENTALIZE THEIR FUNCTIONS Eukaryotic -True nucleus -membrane-bound organelles -cytoplasm in region b/n plasma membrane & nucleus *Protists, fungi, animals & plants Prokaryotic -No true nucleus -No membrane- bound organelles -DNA in an unbound region called the nucleoid -cytoplasm bound by plasma membrane *Bacteria & Archaea -Plasma membrane -Cytosol -Chromosomes -Ribosomes
    4. 4. Fimbriae Bacterial chromosome A typical rod-shaped bacterium (a) Nucleoid Ribosomes Plasma membrane Cell wall Capsule Flagella FIGURE6.5-CAMPBELL BIOLOGY9TH EDITION Prokaryotic Cell (Bacterial Cell)
    5. 5. EUKARYOTIC CELLS A eukaryotic cell has internal membranes that partition the cell into organelles Plant and animal cells have MOST of the same organelles
    6. 6. ENDOPLASMIC RETICULUM (ER) Rough ER Smooth ER Nuclear envelope Nucleolus Chromatin Plasma membrane Ribosomes Golgi apparatus LysosomeMitochondrion Peroxisome Microvilli Microtubules Intermediate filaments Microfilaments Centrosome CYTOSKELETON: Flagellum NUCLEUS
    7. 7. NUCLEUS Nuclear envelope Nucleolus Chromatin Golgi apparatus Mitochondrion Peroxisome Plasma membrane Cell wall Wall of adjacent cell Plasmodesmata Chloroplast Microtubules Intermediate filaments Microfilaments CYTOSKELETON Central vacuole Ribosomes Smooth endoplasmic reticulum Rough endoplasmic reticulum FIGURE 6.8C
    8. 8. The plasma membrane is SEMI-PERMEABLE • The plasma membrane is a SELECTIVE BARRIER that allows certain molecules to move in and out of the cell
    9. 9. FIGURE 6.6 Outside of cell Inside of cell 0.1 m (a) TEM of a plasma membrane Hydrophilic region Hydrophobic region Hydrophilic region Carbohydrate side chains ProteinsPhospholipid (b) Structure of the plasma membrane
    10. 10. WHAT MOLECULES CAN AND CANNOT MOVE FREELY ACROSS THE MEMBRANE? WHY? Nonpolar molecules pass through cell membranes more readily than polar molecules because the center of the lipid bilayer (the fatty acid tails) is nonpolar and does not readily interact with polar molecules.
    11. 11. PROTEIN FACTORIES Ribosomes use the information from the DNA to make proteins • Ribosomes are like “factories” • Site of protein synthesis Ribosomes are located in the cytosol as free ribosomes or attached to the rough endoplasmic reticulum
    12. 12. INFORMATION ZONE The nucleus contains most of the DNA in a eukaryotic cell • The nucleus is the “brain” of the cell • DNA is organized into units called CHROMOSOMES, which contain genetic information The nuclear envelope encloses the nucleus, separating it from the cytoplasm Pores control which molecules enter and leave the nucleus Chromatin Nucleus Nucleolus Nuclear envelope: Inner membrane Outer membrane Nuclear pore
    13. 13. BIOSYNTHETIC FACTORY OR CONVEYOR BELT The endoplasmic reticulum (ER) accounts for more than half of the total membrane in many eukaryotic cells The ER membrane is continuous with the nuclear envelope There are two distinct regions of ER • Smooth ER, which lacks ribosomes • Rough ER, surface is studded with ribosomes
    14. 14. Smooth ER Rough ER ER lumen Cisternae Ribosomes Smooth ER Transport vesicle Transitional ER Rough ER 200 nm Nuclear envelope
    15. 15. ENDOPLASMIC RETICULUM Smooth Synthesizes lipids Metabolizes carbohydrates Detoxifies drugs & poisons (liver & kidney cells) Stores calcium ions Rough Has bound ribosomes Production of glycoproteins (proteins covalently bonded to carbohydrates) Is a membrane factory for the cell Distributes transport vesicles, proteins surrounded by membranes
    16. 16. SHIPPING AND RECEIVING CENTER The Golgi apparatus consists of flattened membranous sacs called cisternae Functions of the Golgi apparatus • Modifies products of the ER • Manufactures certain macromolecules • Sorts and packages materials into transport vesicles
    17. 17. GARBAGE DISPOSAL OR JANITORS • A lysosome is a membranous sac of hydrolytic enzymes that can digest macromolecules • Lysosomal enzymes work best in the acidic environment inside the lysosome
    18. 18. VACUOLE: WATER HOLE A plant cell or fungal cell may have one or several vacuoles, derived from endoplasmic reticulum and Golgi apparatus Central vacuoles, found in many mature plant cells, hold organic compounds and water
    19. 19. Central vacuole Cytosol Nucleus Cell wall Chloroplast Central vacuole 5 m
    20. 20. ENERGY PRODUCTION SITES Mitochondria (Powerhouse- Duke Power) Cellular Respiration a metabolic process that uses oxygen to generate ATP Chloroplast (Solar Power Plant) Photosynthesis Found in plants & algae
    21. 21. Intermembrane space Outer membrane DNA Inner membrane Cristae Matrix Free ribosomes in the mitochondrial matrix (a) Diagram and TEM of mitochondrion 0.1 m Mitochondrial DNA Nuclear DNA Mitochondria 10 m The mitochondrion, site of cellular respiration.
    22. 22. CHLOROPLASTS: CAPTURE OF LIGHT ENERGY Chloroplasts contain the green pigment chlorophyll, as well as enzymes and other molecules that function in photosynthesis Chloroplasts are found in leaves and other green organs of plants and in algae Chloroplast structure includes Thylakoids, membranous sacs, stacked to form a granum Stroma, the internal fluid
    23. 23. Ribosomes Stroma Inner and outer membranes Granum 1 mIntermembrane spaceThylakoid (a) Diagram and TEM of chloroplast Chloroplasts (red) 50 m DNA THE CHLOROPLAST, SITE OF PHOTOSYNTHESIS
    24. 24. CELL WALLS OF PLANTS Animal cells DO NOT have cell walls • Plants, Prokaryotes, Fungi, and some Protists have cell walls The cell wall protects the plant cell, maintains its shape, and prevents excessive uptake of water Plant cell walls are made of cellulose fibers