Lecture 21 - Prokaryotes 1 Flashcards Preview

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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

what happens in cyanobacterium Anabaena?

-photosynthetic cells + heterocysts exchange metabolic products