BIOL2051_Ch

BIOL2051_Ch - 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 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-bound organelles Bacteria & Archaea   2.  Eukaryote Membrane-bound organelles (nucleus, chloroplast, mitochondria, etc) algae, fungi, protozoa, plants, animals Viruses (They are their own category; 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)
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Eukaryotes – several linear chromosomes Nucleus - membrane-enclosed structure that contains the chromosomes – found in eukaryotes Nucleoid - mass of DNA not bound by a membrane- found in eukaryotes The Bacterial Cell Cytoplasm surrounded by envelope o Cytoplasm contains DNA in nucleoid Envelope has lipid membrane boundry o 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 o CM is a phospholipid bilayer o Phospholipid- Hydrophilic (dissolves in H 2 O) group faces cytoplasm or periplasm Hydrophobic (does not dissolve in H 2 O) fatty acids line up inside the 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 o Peripheral membrane proteins- are bound to the surface of the membrane o Cytoplasmic Membrane: Functions 1. Permeability barrier: a. Prevents leakage of cytoplasmic metabolites into environment.
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b. Transport of substances (nutrients & waste products) into & out of cell Due to hydrophilic outside and hydrophobic center of the membrane, only water can freely diffuse through the membrane Other compounds must be transported- usually by integral and peripheral membrane proteins 2. Protein anchor- site of many proteins involved in transport, bioenergetics, and chemotaxis 3. Energy conservation- site of generation & use of the proton motive force a. Respiration 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 The Bacterial Cell Wall (aka: sacculus)
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This note was uploaded on 05/07/2011 for the course BIOL 2153 taught by Professor Larkin during the Spring '03 term at LSU.

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BIOL2051_Ch - Chapter 3 Cell Structure and Function Basic...

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