Chapter 3

Chapter 3 - Chapter3 Tuesday,January20,2009 9:55AM

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Chapter 3 Tuesday, January 20, 2009 9:55 AM Chapter 3 Cell Structure and Function   Basic cellular structures: 1. Cytoplasm 2. Cytoplasmic membrane 3. Nucleus or nucleoid Nucleoid is not surrounded by a membrane 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-bound organelles (nucleus, chloroplast, mitochondria, etc) 1 domain - algae, fungi, protozoa, plants, animals   Viruses (THEY ARE THEIR OWN CATEGORY. THEY ARE NOT IN ANY DOMAIN OR TREE) Non-cellular Reproduce only inside a host cell Lack many characteristics of living things Ex. HIV virus, Rhinoviruses (colds)    Arrangement of DNA in Microbial Cells genome - a cell's complete set of genes DNA is arranged to form chromosomes Prokaryotes - have a single circular chromosome and sometimes circular  extrachromosomal DNA (plasmids) Eukaryotes - several linear chromosomes (23 pairs - humans) Nucleus -  membrane-enclosed structure that contains the chromosomes – found  in eukaryotes  Nucleoid -  mass of DNA not bound by a membrane - found in prokaryotes
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  The Bacterial Cell Cytoplasm surrounded by envelope Cytoplasm contains DNA in nucleoid  Envelope has lipid membrane boundary Plus structural cell wall   Bacterial cell structures cytoplasmic membrane -  “fluid” selective permeability barrier made of  phospholipids and proteins that form a bilayer with hydrophilic exteriors (are exposed to  water) and a hydrophobic interior  CM is a phospholipid bilayer  Phospholipid-  Hydrophilic (dissolve in water) group faces cytoplasm or periplasm  Hydrophobic (don’t dissolve in water) fatty acids line up inside  membrane Attraction of nonpolar fatty acid portions of one phospholipid layer for  other layer result in  Selective permeability of cell membrane. Integral membrane proteins- span membrane Peripheral membrane proteins- are bound to surface of membrane Cytoplasmic Membrane: Functions Permeability barrier: Prevents leakage of cytoplasmic metabolites into  environment.  out of cell Due to hydrophilic outside and hydrophobic center of  membrane, only water can freely diffuse through  membrane Other compounds must be transported- usually by  integral and peripheral membrane proteins Protein anchor- site of many proteins involved in transport,  bioenergetics, and chemotaxis
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This note was uploaded on 03/31/2009 for the course BIOL 2051 taught by Professor Brininstool during the Spring '07 term at LSU.

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Chapter 3 - Chapter3 Tuesday,January20,2009 9:55AM

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