Lecture 21 - Prokaryotes 1 Flashcards Preview

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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

What is phototaxis?

-movement toward or away from light