Ch 28: Prokaryotes Flashcards
0
Q
Prokaryotes
A
- Unicellular
- Most are less than 1 mm
- Nucleolid
- chromosome is 1 circular
double-stranded DNA - often have plasmids
- chromosome is 1 circular
- Cell division
- most div by binary fission
(No mitosis process)
- most div by binary fission
- Genetic recombination
- NOT reproduction
- Internal compartmentalization
- no membraned organelles
- No internal compartment
- Flagella
- diff from euk flagella
- Metabolic diversity
- oxygenic & anoxygenic
photosynthesis - chemolithotrophic (can use
energy stored in bonds of
inorganic molecules
- oxygenic & anoxygenic
1
Q
Prokaryotic diversity
A
- Oldest, structurally simplest,
& most abundant forms of life
- Falls into 2 domains:
-bacteria (a.k.a. eubacteria)
-Archaea
2
Q
Bacteria
A
- Plasma membrane
- Bacterial lipids are unbranched
- use Ester bonds
- Cell wall
- have peptidoglycan
- DNA replication
- single replication origin
3
Q
Archaea
A
- Plasma membrane
- formed on glycerol skeleton
- use ether linkages (not ester)
- hydrocarbons may be
branched or have rings - tetraether polymer allows
extremophiles to withstand
high temps
- Cell wall
- lacks peptidoglycan
- DNA replication
- sim to eukaryotes
- single rep origin
- Gene expression
- transcription/translation
sim to eukaryotes
- enzymes are sim
- transcription/translation
4
Q
Classification characteristics
A
Early:
Relied on staining characters & observable phenotypes
- Photosynthetic or not
- Motile or not
Newer:
- Amino acid seq of key proteins
- % guanine – cytosine content
- Nucleic acid hybridization
-closely related species: more
base pairing
- Gene & RNA sequencing
- Whole genome sequencing
5
Q
Prokaryotic cell structure
A
3 basic shapes
- bacillus: Rod shaped
- coccus: spherical
- spirillum: helical shaped
Cell wall
- peptidoglycan
- withstands hypotonic envir.
Gram stain
- Gram+ :
- thick pg wall; stain purp color
- contain lipoteichoic &
teichoic acid
- Gram– :
- thin pg; stain pink
- 2nd outer membrane w/
lipopolysaccharide
- resistant to many antibiotics
6
Q
Endospores
A
- Develop thick wall around genome & small portion of cytoplasm - Highly resistant to environmental stress (especially heat) - When conditions improve, germinate & return to normal cell division - Bacteria causing tetanus, botulism, & anthrax
7
Q
Horizontal gene transfer
A
3 types:
- Conjugation: cell to cell contact
- Transduction: by bacteriophages
- Transformation: from environ.
8
Q
Transduction
A
Generalized transduction
- Occurs by accident in lytic cycle
- Viruses package bacterial DNA
& transfer it in subsequence
infection
Specialized transduction
- Occurs by accident in lysogenic
cycle
- imprecise excision of prophage
DNA
- Only few host genes can be
transferred
9
Q
Transformation
A
Natural transformation
- Occurs in many bacterial
species
- DNA that is released from dead
cell picked up by live cell
- Proteins involved encoded by
bacterial chromosome
Artificial transformation
- Some species don't nat.
transform
- Accomplished in a lab
- Used to transform E. coli for
molecular cloning
10
Q
Bioremediation
A
- Bacteria are used
- Remove pollutants from water,
air, & soil - Bio stimulation: adds nutrients to
encourage growth of naturally
occurring microbes
11
Q
Symbiosis
A
- Refers to ecological
relationship bet. diff
species that live in direct
contact with each other
12
Q
Mutualism (symbiosis)
A
Both parties benefit
-Nitrogen – fixing bacteria on
plant roots
-Cellulase – producing bacteria
in animals
13
Q
Commensalism (symbiosis)
A
One organism benefits & other is unaffected
14
Q
Parasitism (symbiosis)
A
One organism benefits and other is harmed
