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USC - BIOL 102 - Class Notes - Week 6

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USC - BIOL 102 - Class Notes - Week 6

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background image Chapter 26 Notes Prokaryotes  o Structure No nuclear membrane Most are very small Very populous Common shapes spheres rods and spirals Surface structures that stick  Exhibit taxis  Move relative to a stimulus Flagella are a common structure o Not analogous o Made of different compounds o Divided into Bacteria and Archaea  Unicellular o Likely first life  o Can create endospores Survive harsh conditions for centuries o Have circular, simpler DNA A single circular chromosome Nucleoid region Smaller rings called plasmids (Bacteria) o Reproduction Binary fission 1 minute ­3 hours Not sexual, no recombination in a meiotic sense Genetic diversity Rapid reproduction Mutation Genetic recombination o DNA moves between two cells via transformation,  transduction, and conjugation o Transformation: uptake of DNA from environment o Transduction: movement of genes by bacteriophages  (viruses) o Conjugation: Similar to sexual reproduction, one cell  attaches to another by a pilus, pulls it closer and transfers 
DNA
The presence of a pilus requires a gene for it Called F factor or F plasmid Occasionally part of the chromosome R plasmids carry antibiotic resistance
background image o Metabolic diversity Photoautotrophs Make ATP from light Chemoautotrophs Extract energy from harsh chemicals Photoheterotrophy Light and others Chemoheterotrophy  Chemicals and others Oxygen Obligate aerobes o Require O2 Obligate anaerobes o Poisoned by oxygen o Use fermentation Facultative anaerobes  o With or without O2 Nitrogen Fixation N2­> NH3 (ammonia)  o Prokaryotic diversity  Some plants have an organ specifically for nitrogen fixing prokaryotes Keep oxygen out  Rhizobium  Handful of soil may contain 10,000 species of prokaryotes Horizontal gene transfer obscures root of tree of life Agrobacterium produces tumors in plants and is used in genetic 
engineering
Transfers genes into plants o Inter­domain transfer o Without prokaryotes, prospects for any other life would be dim.  Chemical recycling  Symbiotic relationships Bacteria only o Have cell wall ( ONLY  Bacteria) Made of peptidoglycan (vs cellulose or chitin) Gram­positive bacteria have simpler walls with a large amount of 
peptidoglycan
Gram­negative have less peptidoglycan and an outer membrane that can 
be negative (added lipopolysaccharide)
More likely to be antibiotic resistant A protein layer called a capsule covers many prokaryotes o Some have folds in membrane that serve a function
background image Still NOT organelles Archaea o Similar to both Eukarya and Bacteria Closer to Eukarya More shared characteristics o Severe conditions Methanogens Produce methane Poisoned by O2 Halophiles High salt content Thermophiles High temperature Symbiosis o Organisms have a relationship o Larger host o Smaller symbiont  o Prokaryotes commonly form symbiotic relationships o Types of relationships Mutualism Both benefit Most bacteria Examples: Chemoautotrophic bacteria in hydrothermal vents are 
the primary producers, others live off of them; intestinal bacteria
Commensalism One benefits, one neutral Parasitism Symbiont harms the host  Pathogens o Parasite that may be fatal Exotoxins Secreted Cause disease even if the producer is not 
present
Endotoxins Released when bacteria die Outer membrane of Gram­negative bacteria Prokaryotes in research o E. coli is used in gene cloning  o Bacteria can be used to make plastics o Bioremediation Removing harmful substances from environment

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School: University of South Carolina
Department: Biology
Course: General Biology
Professor: Mihaly Czako
Term: Fall 2016
Tags: plants, diversity, Bacteria, archea, and protists
Name: Week 6 Notes
Description: Chapters 27-30 Both plant diversity chapters, bacteria and Archea and protists 9/20 and 9/22
Uploaded: 09/19/2016
9 Pages 18 Views 14 Unlocks
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