Flashcards in Lecture 21 - Prokaryotes 1 Deck (74)
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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
