Bio 101 Day 11

Bio 101 Day 11 - Prokaryotic Cells -Two DomainsBacteria and...

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Prokaryotic Cells -Two Domains—Bacteria and Archaea -Very small—1-5um (l), .5-1um (d) -Most are unicellular: -form colonies, filaments -Do not have membrane-enclosed organelles -such as nuclei and mitochondria Bacterial Shapes -Rods and Spherical (cocci) -Biplococci -Chains (srapto-) -Clumps (staphylo-) -Spiral Prokaryotic Cells -Cell walls composed of peptidoglycan, a sugar polymer surrounding entire PM -Resists hypotonic (bursting) but will shrink in hypertonic environment -Some have a capsule (glycocalyx) surrounding cell wall -e.g. Streptococcus pneumonia (without capsule doesn’t cause disease) Gram-Positive Cell Wall -Walls very think -Consist mainly of peptidoglycan -Gram positive (stain with crystal violet) -Penicillin sensitive (interferes with peptidoglycan synthesis) Gram-Negative Cell Wall -Walls have thin peptidoglycan layer and outer membrane (like a second plasma membrane) -Gram negative (stain washes out with alcohol) -Many are Penicillin resistant
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Bacteria Pili -Protein structures extending from cell -help bacteria adhere to one another or to other surfaces -Some help transmit DNA between bacteria (sex pili) Bacterial Flagella -Different from eukaryotic glagella: no microtubules (no 9+2 arrangement) -Consist of basal body (motor)-energy from ATP pumps protons out of the cell, while diffusion of these protons back into the cell then powers the motor -hook (connector) and filament -Produce rotary motion and propels the cell forward -Important chemotaxis (e.g. toward food) Prokaryotic Genes -Genetic material consists of -1 circular DNA molecule -1 or more plasmids (circular DNA fragments) -Replicate independently of genomic DNA -Can integrate and therefore -Can lead to genetic exchange -Resistance to antibiotics Asexual Reproduction -Binary Fission -cell divides, forming two cells -Budding -bud forms, separates from mother cell -Fragmentation -Walls form inside cell
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-separates into several cells General Material Exchange (horizontal gene transfer) Transformation -Bacterial cell takes in DNA fragments released by another cell e.g. phage DNA (via DNA binding proteins)—phage integrates Transduction -During bacterial lysis-cell releases phage carrying bacterial genes from one bacterial cell into another Conjugation -Two cells of different mating types exchange genetic material -This F factor (also called F plasmid) contains 20 genes—important in conjugation -Encodes enzymes necessary to transfer DNA and produce the sex pili Modes of Nutrition: Heterotrophs -Chemoheterotrophs -free-living decomposes -obtain carbon and energy from dead organic matter (glucose etc.) -Some pathogens, and obtain nourishment from infected hosts
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This note was uploaded on 04/06/2010 for the course BIO 01-119-10 taught by Professor D'arville during the Fall '09 term at Rutgers.

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Bio 101 Day 11 - Prokaryotic Cells -Two DomainsBacteria and...

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