Flashcards in Lecture 21 - Prokaryotes 1 Deck (74):
1
Where do prokaryotes thrive?
-almost everywhere
-even too acidic, salty, cold , or hot for other organisms
2
Are prokaryotes macroscopic or microscopic?
microscopic
3
What are the two domains of prokaryotes?
1. bacteria
2. archaea
4
What are the 3 elements of the tree of life?
1. bacteria
2. archaea
3. eukaryotes
5
Archaea are more closely related to ______ than to ________
Eukaryotes, Bacteria
6
What were earth's first organisms?
prokaryotes
7
Are prokaryotes uni or multicellular?
unicellular, but some species form colonies
8
How small are most prokaryotic cells?
0.5-5 micron
9
What are the 3 most common shapes of prokaryote cells?
1. spheres (cocci
2. rods (bacilli)
3. spirals
10
What is trichodesmium?
colonial marine nitrogen-fixing cyanobacterium
11
What is the important feature of nearly all prokaryotic cells?
cell wall
12
What do cell walls do?
-maintains cell shape
-protects cell
-prevents it from bursting in a hypotonic environment
13
What are eukaryote cell walls made of?
-cellulose
-chitin
14
What are bacterial cell walls made of?
peptidoglycan
15
What is peptidoglycan?
-network of sugar polymers
-cross-linked by polypeptides
16
What doe archaea contain? lack?
-polysaccharides + proteins
-lack peptidoglycan
17
What is a gram stain used for?
to classify bacteria by cell wall composition
18
What will a gram-positive bacteria have?
-simpler walls with a large amount of peptidoglycan
19
What do gram-neg bacteria have?
-less peptidoglycan
-outer membrane that can be toxic
20
What do many antibiotics target? What do they do?
-peptidoglycan
-damage bacterial cell walls
21
Which type are more likely to be antibiotic resistant?
gram-negative
22
What also covers many prokaryotes?
capsule (slime layer)
23
What is an endospore?
-seed that forms inside cell (with DNA)
-inactive, can remain viable in harsh conditions for centuries
24
What do fimbriae do?
-allow prokaryotes to stick to their substrate or other individuals in a colony
25
What are pili?
-longer than fimbriae
-allow prokaryotes to exchange DNA
26
What are taxis?
ability to move toward or way from a stimulus
27
What is chemotaxis?
-movement toward or away from chemical stimulus
28
How do motile bacteria propel themselves?
-flagella scattered about the surface or concentrated at one or both ends
29
What are flagella composed of?
-different proteins
-likely evolved independently
30
What is phototaxis?
-movement toward or away from light
31
What are the 3 parts of a flagella?
1. motor
2. hook
3. filament
32
What is exaptation?
existing structures take on new functions through descent with modification
33
prokaryotic cells usually lack
-complex compartmentalization
-organelles
34
what do some prokaryotes have? specialized _____
membranes that perform metabolic functions
35
the _____ genome has less DNA than the _____ genome
prokaryotic, eukaryotic
36
what does most of the genome consist?
circular chromosome
37
where is the chromosome located?
in the nucleoid region
38
What are plasmids?
smaller rings of DNA
39
What is the benefit of having differences between prokaryote and eukaryotic DNA replication, transcription, translatioN/
-allow people to use some antibiotics without harming themselves
40
How do prokaryotes reproduce?
binary fission
41
What are 3 key features of prokaryotic reproduction?
1. they are small
2. they reproduce by binary fission
3. short generation times
42
What is an example of an extremophile bacteria?
-endoliths
43
What are endoliths?
live inside rocks + between mineral grains
44
What are 3 qualities of endoliths?
1. found as deep as 2 miles below surface
2. most are chemoautogtorphs
3. reproduce maybe once per century
45
What is characteristic of prokaryotic offspring?
generally identic
46
Mutation rates are ____ during binary fission
low
47
What is a result of rapid reproduction?
mutations can accumulate rapidly in a population
48
Are prokaryotes primitive?
highly evolved
49
What is the Lenski long-term evolution experiment?
-ongoing study in experimental evolution
-tracking genetic changes in 12 initially identical populations
50
How can prokaryotic DNA be brought together?
-transformation, transduction, conjugation
51
what is horiziontal gene transfer
-move through completely unrelated bacteria species
52
what happens in transformation?
-prokaryotic cell take up and incorporate DNA from surrounding environment
53
What is transduction?
movement of genes between bacteria by bacteriophages
54
What are the 5 steps of a virus infecting bacteria?
1.
2.
3.
4.
5.
55
What is conjugation?
process where genetic material is transferred between prokaryotic cells
56
What happens when a donor cell attaches to a recipient?
pulls it closer, transfers DNA
57
what is the F factor?
piece of DNA required for the production of the pili
58
What are 4 steps of conjugation?
1.
2.
3.
4.
59
What does a cell with the F factor built into its chromosomes function as?
donor during conjugation
60
What does the recipient become?
recombinant bacterium (DNA from 2 different cells)
61
What are R plasmids?
carry genes from antibiotic resistance
62
How do R plasmids work with antibiotics?
resistant to antibiotics
63
What are phototrophs?
obtain energy from light
64
What are chemotrophs?
obtain energy from chemicals
65
What are autotrophs?
require CO2 as carbon source
66
What are heterotrophs?
require organic nutrient to make organic compounds
67
What are 4 major modes of nutrition?
1. photoautotorphy
2. chemoautotrophy
3. photoheterotrophy
3. chemoheterotropy
68
What are obligate aerobes?
require O2 for cellular respiration
69
What are obligate anaerobes?
-poisoned by O2
-use fermentation or anaerobic respiration
70
What are facultative anaerobes?
can survive with or without O2
71
What is nitrogen essential for?
production of amino acids, nucleic acids
72
What is nitrogen fixation?
some prokaryotes convert N2 to NH3
73
what are heterocysts?
nitrogen fixing cells
74