Biolog 4 - Chapter 4: Cell Structure and Function A. What...

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Chapter 4: Cell Structure and Function A. What is a “Cell?” 1. Basic structure Cell – smallest unit with properties of life, capacity for metabolism, controlled responses to environment, growth and reproduction Plasma membrane (cell membrane) Distinct entity, separates metabolic activities Nucleolus (membrane bound internal sac) DNA occupied (eukaryotes) Nucleoid – not enclosed in a membrane sac Cytoplasm – semi-fluid matrix Ribosomes (dots on the ER) where proteins are built 2. Cell membrane (fluid mosaic model) Lipid bilayer – continuous, oily boundary that prevents the free passage of water soluble subsaances across it. (two layers of phospholipids) 3. Surface to volume ratio Cell expands in diameter, then volume increases faster than its surface area (basically constrains size of cell) Influences cell shape and function of organisms B. Prokaryotic cells 1. Bacteria and Archaeans Low abundance of organelles, no nucleus Smallest known cells Bacteria start with formylmethionine chain and Archaeans start with methionine chain like eukaryotic cells also make a few histones Pathogenic bacteria have jelly-like wall Have flagellum and pilus DNA not in nucleus
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C. Eukaryotic cells Contain nucleus and organelles, all start out life with nucleus, ribosomes, and cytoskeleton 1. Plant cell Chloroplast, cell wall, lysosome-like, vacuole 2. Animal cell Centrioles, lysosomes 3. Protistans, Fungi D. Nucleus Functions: keeps DNA from getting tangled, and control movement of substance in cytoplasm Nuclear envelope – double-membrane system where two lipid bi-layers are pressed together, ribosomes bound to it.
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Nucleoplasm is like cytoplasm, except in nucleus and anchors DNA Nucleolus – constructs RNA and proteins. Chromosomes are double-stranded DNA with chromatin as cell’s DNA Chromosome structure changes in different stages of eukaryotic cell life E. Endomembrane System Cell nucleus – DNA instructions for making proteins are transcribed in the nucleus and moved to the cytoplasm Rough ER – polypeptide chain enters and undergoes modification inserted into
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This note was uploaded on 12/03/2011 for the course CHEM BIO P 101 taught by Professor Kk during the Spring '11 term at Rochester.

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Biolog 4 - Chapter 4: Cell Structure and Function A. What...

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