MICRO CH3

MICRO CH3 - Chapter 3 Cell Structure and Function Basic...

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Chapter 3 Cell Structure and Function Basic cellular structures: 1. cytoplasm 2. cytoplasmic membrane 3. nucleus or nucleoid 4. ribosomes- (protein synthesis) 5. cell wall- found in plants & most prokaryotes; not in animals Two types of cells: 1. Prokaryote simpler internal structure lack membrane-enclosed organelles Bacteria & Archaea 2. Eukaryote Membrane enclosed organelles (nucleus, chloroplast, mitochondria, etc) algae, fungi, protozoa, plants, animals Viruses Non- cellular Reproduce only inside a host cell Lack many characteristics of living things Ex. HIV virus, Rhinoviruses (colds) The Bacterial Cell Cytoplasm surrounded by envelope o Cytoplasm contains DNA in nucleoid Envelope has lipid membrane boundary o Plus structural cell wall Bacterial cell structures
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cytoplasmic membrane - “fluid” selective permeability barrier made of phospholipids and proteins that form a bilayer with hydrophilic exteriors and a hydrophobic interior o CM is a phospholipid bilayer each layer is a “leaflet” o Phospholipid- Glycerol with ester links to 2 fatty acids Hydrophilic (dissolve in water) group faces cytoplasm or periplasm Hydrophobic (don’t dissolve in water) fatty acids line up inside membrane o Attraction of nonpolar fatty acid portions of one phospholipid layer for other layer result in Selective permeability of cell membrane. o Integral membrane proteins- span membrane, all the way across membrane from one side to another o Peripheral membrane proteins- are bound to surface of membrane o Cytoplasmic Membrane: Functions 1. Permeability barrier: prevents leakage of cytoplasmic metabolites into environment a. Prevents leakage of cytoplasmic metabolites into environment. b. Transport of substances (nutrients & waste products) into & out of cell Due to hydrophilic outside and hydrophobic center of membrane, only water & small uncharged molecules can freely diffuse through membrane Other compounds must be transported (active or passive) by specific membrane proteins 2. Structural Support- site of many proteins involved in transport, 3. Energy conservation- site of generation & use of the proton motive force a. Respiration
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Eukaryotes have mitochondria to generate energy by respiration In prokaryotes, respiration occurs in the cytoplasmic membrane b. Photosynthesis Photosynthetic eukaryotes have chloroplasts to carry out photosynthesis Photosynthetic prokaryotes carry out photosynthesis in the cytoplasmic membrane o To reinforce the membrane: - Eukaryotes have sterols such as cholesterol - Bacteria have hopanoids - Archaea have terpenoids, which increase stability at high temp & low pH The Bacterial Cell Wall (sacculus) o made of peptidoglycan (murein)- a porous cage-like structure sugar chains wrapped in circles around cell “glyco” = sweet Sugar chains linked to each other by short polymers of amino acids
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MICRO CH3 - Chapter 3 Cell Structure and Function Basic...

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