Chapter 11: Characyerizing and classifying prokaryotes Flashcards
Prokaryotes
-the mot diverse group of organisms on the planet
-they are found everywhere on the planet (glaciers, hot springs, colons of animals, supersaturated brines)
-rarely capable of pathogenicity
-diverse morphologies
Bergey’s manual of systematic
-organizes taxonomy info for identification and cataloging microbes
Prokaryotes reproduce mostly by
- asexual reproduction (more specific binary fission)
Ways prokaryotes reproduce
- binary fission (most common)
2.snapping division (results in V arrangement or palisades) - Budding
- Formation of asexual spores
- fragmentation
Steps in binary fission
- cell replicates its DNA
- The cytoplasmic membrane elongates, separating DNA molecules
- Cross wall forms and membrane invaginates
- Cross wall forms completely
- daughter cells
What are the reasons for different cell arrangement during binary fission?
- Number of planes
- separation vs non separation of daughter cells
How are some organisms named?
-Often named by shape and or arrangement of the cells
What does a single plane of division produce in cocci?
- diplococci or streptococci
What do 2 plane divisions produce in cocci?
-tetrads
What do 3 plane divisions produce in cocci?
-Sarcina or staphylococci
Why are arrangements of bacilli less varied?
-they are less varied b/c they only divide along a single transverse plane
Archaeans lack what in their cell walls?
-they lack peptidoglycan in their walls, but they use proteins, glycoproteins, lipoproteins or other polysaccharides
-their cell membrane phospholipids have branched hydrocarbon chains
Archaeans reproduce by?
-asexual reproduction, more specifically binary fission, but also budding or fragmentation
Archean morphology
-usually cocci, bacilli, or spiral forms but some a pleomorphic
Do archeans cause disease?
no
Example of archeans
Extremophiles and methanogens
Thermophiles and Hyperthermophiles
-Their DNA, RNA, cytoplasmic membranes, and proteins do not function in typical environmental heat
Thermophiles need minimum temperature of 45 C while hyperthermophiles need over 80 C
Name two representative genera of Thermophiles and Hyperthermophiles
-Geogemma and pyrodictium
Haplophiles
-depend on a minimum 9% NACl to maintain their integrity of their cell walls but usually 17-23% to thrive while some need an upward of 35% saline
-have orange and red pigment to protect from UV light
-most studied is halobacterium salinarium
Methanogens
-they convert CO2/H2 gas and organic acids to methane gas and some convert organic wastes in pond, lakes, and ocean sediments to methane
-some live in colonies of animals and they are the primary source of environmental methane
-estimated to have produced 10 trillion tons of methane
-useful in sewage treatments by digesting sludge and make up 1/3 of the biomass in Antarctic waters
Who are the largest groups of archaea
mesophiles
Deeply branching bacteria
-scientists believe these organisms are similar to the earliest bacteria on the planet because they are
1. autotrophic
2. aquifex
3.deinococcus
-can withstand extreme exposure to radiation
Autotrophic
they live in habitats similar to those which scientists believe existed on early earth
aquifex
-is considered to represent earliest branch of bacteria b/c chemoautrophic, hyperthermophilic, anaerobic and obtains carbon from inorganic sources
Deinococcus
-has an outer membrane similar to gram negatives, but stains gram positive
Phototrophs
contains photosynthetic lamellae, layers in the cell membrane used for photosynthesis
List the phototrophic organisms
- Blue green bacteria
- Nitrogen fixers
- green and purple non-sulfur bacteria
4.green and purple sulfur bacteria
Blue-green bacteria
-formerly called blue-green algae, undergo oxygenic photosynthesis like algae and plants using chlorophyll a
-they possible evolved into chloroplast (endosymbiosis)
-ex: cyanobacteria
Nitrogen fixers
-reduce molecular nitrogen into fixed nitrate which is good for plants and then we get to use it.
-this is how we get nitrogen into the food chain
Green and purple non-sulfur bacteria
-anoxygenic and derive electron from organic molecules to reduce CO2