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Microbiology > Ch 8 Microbial Genetics > Flashcards

Ch 8 Microbial Genetics Flashcards

1
Q

DNA contains _____ which are the instructions for making _______ and functional ___’s.

A

genes; proteins; RNA

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2
Q

Protein is:

A

a functional polymer of amino acids

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3
Q

A gene is:

A

a locus (or region) of DNA that encodes a protein or functional RNA product

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4
Q

Where are genes located in bacteria?

A

On large circular chromosomes and sometimes also on plasmids

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5
Q

What are plasmids?

A

Small, extrachromosomal, circular, self-replicating pieces of dsDNA

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6
Q

Are plasmids double or single stranded DNA or RNA?

A

dsDNA

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7
Q

What shape are plasmids?

A

Usually circular

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8
Q

Plasmids contain an origin of ________ (ori), but need _____ ________ to _________.

A

replication; host proteins; replicate

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9
Q

What direction is DNA synthesized in?

A

5’ -> 3’

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10
Q

Leading strand

A

synthesized continuously

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11
Q

Lagging strand

A

synthesized discontinuously in Okazaki fragments

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12
Q

To connect the Okazaki fragments _________ removes _____ _______. Adjacent Okazaki fragments are joined by _____ _______.

A

DNA polymerase; RNA primers; DNA ligase

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13
Q

How does a phosphodiester bond form?

A

through dehydration synthesis

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14
Q

Is DNA polymerase III very accurate in dNTP selection?

A

Yes

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15
Q

Exonuclease proofreading

A

Pol III and Pol I correct mistakes

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16
Q

Transcription begins at the ________ sequence and stops at the ___________ sequence.

A

promoter; terminator

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17
Q

3 phases of transcription

A

initiation, elongation, termination

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18
Q

Transcription initiation

A

the rna polymerase binds to the promoter region and separates the double helix

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19
Q

Transcription elongation

A

RNA polymerase travels along the DNA template and synthesizes RNA

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20
Q

Transcription termination

A

At the end of the gene, RNA polymerase encounters termination signal in DNA. RNA polymerase detaches from DNA and releases the RNA transcript (mRNA).

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21
Q

Translation

A

the synthesis of a protein (amino acids) guided by the template mRNA (nucleotides)

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22
Q

Start Codon

A

AUG

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23
Q

Stop Codon

A

UGA, UAG, UAA

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24
Q

mRNA

A

encodes proteins

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25
Q

rRNA

A

forms ribosomes

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26
Q

tRNA

A

shuttles amino acids to ribosomes

27
Q

_____ is used by the _______ to _______ the mRNA during protein ________.

A

tRNA; ribosome; translate; synthesis

28
Q

What shape is tRNA?

A

clover shaped loop

29
Q

The _______ in tRNA is ____________ to the codon in mRNA and directs the addition of specific ______ _____.

A

anticodon; complimentary; amino acids

30
Q

What are the three binding sites for tRNA on a 70S ribosome?

A

Acceptor (A) site, Peptidyl-tRNA (P) site, Exit (E) site

31
Q

A site

A

binds incoming aminoacyl-tRNA

32
Q

P site

A

contains the tRNA with the growing polypeptide chain

33
Q

E site

A

binds a tRNA recently stripped of its polypeptide

34
Q

Transcription and translation are _______ _________ in eukaryotes but not prokaryotes.

A

physically separated

35
Q

mutations

A

changes in the genetic material (DNA)

36
Q

mutagen

A

agent that causes mutation

37
Q

spontaneous mutation

A

occur in the absence of a mutagen (during DNA replication)

38
Q

base substitution (point mutation)

A

change in one base

39
Q

silent mutation

A

no change in the amino acid sequence

40
Q

missense mutation

A

results in one changed amino acid in the protein sequence

41
Q

nonsense mutation

A

codon is changed to a STOP codon, resulting in a truncated protein

42
Q

frameshift mutation

A

insertion or deletion of 1 or more nucleotide pairs

43
Q

4 Characteristics of Nuceloside Analogs

A

look like nitrogenous bases, can replace normal base during replication, cause mistakes in base pairing, result in base substitution

44
Q

Nucleoside analogs can be useful for _______ & ________.

A

medicine; research

45
Q

Ionizing radiation (xrays and gamma rays)

A

causes the formation of ions that can react with nucleotides and the deoxy- backbone

46
Q

thymine dimers can be repaired by ______ _____ _____

A

nucleotide excision repair

47
Q

Photolyases

A

separate thymine dimers

48
Q

constitutive genes

A

expressed at a fixed rate

49
Q

repressible genes

A

turn off expression

50
Q

inducible genes

A

turn on expression

51
Q

repressors

A

bind to regulatory sequences in the DNA and prevent transcription of target genes

52
Q

activators

A

bind to regulatory sequences in the DNA and stimulate transcription of target genes

53
Q

operon

A

a set of coordinately regulated genes that share a single mRNA

54
Q

the lac operon is ______

55
Q

beta-galactosidase

A

hydrolyzes lactose into glucose and galactose

56
Q

lactose permease

A

a membrane protein that transports lactose into the cell

57
Q

The lac repressor is _______ _______.

A

continually expressed

58
Q

The repressor protein binds to the ________ sequence and blocks the ________ sequence.

A

operator; promoter

59
Q

To inactivate the lac repressor, ____________ binds to the _______ protein, making it unable to bind.

A

Allolactose, repressor

60
Q

_____ ___________ binds to the lac promoter and transcription proceeds.

A

RNA polymerase

61
Q

What accumulates when there is no glucose?

62
Q

cAMP binds to the _____

A

CAP (Catabolic activator protein)

63
Q

CAP is now active and stabilizes the binding of ____ _______ to the lac ____________.

A

RNA polymerase; promoter

64
Q

2 transcription differences between eukaryotes and prokaryotes

A
  1. transcription and translation happen simultaneously in prokaryotes 2. eukaryotes have introns (taken out) and exons

Microbiology (21 decks)

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