Ch 8 Microbial Genetics

Question 1

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

Answer 1

genes; proteins; RNA

Question 2

Protein is:

Answer 2

a functional polymer of amino acids

Question 3

A gene is:

Answer 3

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

Question 4

Where are genes located in bacteria?

Answer 4

On large circular chromosomes and sometimes also on plasmids

Question 5

What are plasmids?

Answer 5

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

Question 6

Are plasmids double or single stranded DNA or RNA?

Answer 6

dsDNA

Question 7

What shape are plasmids?

Answer 7

Usually circular

Question 8

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

Answer 8

replication; host proteins; replicate

Question 9

What direction is DNA synthesized in?

Answer 9

5’ -> 3’

Question 10

Leading strand

Answer 10

synthesized continuously

Question 11

Lagging strand

Answer 11

synthesized discontinuously in Okazaki fragments

Question 12

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

Answer 12

DNA polymerase; RNA primers; DNA ligase

Question 13

How does a phosphodiester bond form?

Answer 13

through dehydration synthesis

Question 14

Is DNA polymerase III very accurate in dNTP selection?

Answer 14

Yes

Question 15

Exonuclease proofreading

Answer 15

Pol III and Pol I correct mistakes

Question 16

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

Answer 16

promoter; terminator

Question 17

3 phases of transcription

Answer 17

initiation, elongation, termination

Question 18

Transcription initiation

Answer 18

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

Question 19

Transcription elongation

Answer 19

RNA polymerase travels along the DNA template and synthesizes RNA

Question 20

Transcription termination

Answer 20

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

Question 21

Translation

Answer 21

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

Question 22

Start Codon

Answer 22

AUG

Question 23

Stop Codon

Answer 23

UGA, UAG, UAA

Question 24

mRNA

Answer 24

encodes proteins

Question 25

rRNA

Answer 25

forms ribosomes

Question 26

tRNA

Answer 26

shuttles amino acids to ribosomes

Question 27

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

Answer 27

tRNA; ribosome; translate; synthesis

Question 28

What shape is tRNA?

Answer 28

clover shaped loop

Question 29

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

Answer 29

anticodon; complimentary; amino acids

Question 30

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

Answer 30

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

Question 31

A site

Answer 31

binds incoming aminoacyl-tRNA

Question 32

P site

Answer 32

contains the tRNA with the growing polypeptide chain

Question 33

E site

Answer 33

binds a tRNA recently stripped of its polypeptide

Question 34

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

Answer 34

physically separated

Question 35

mutations

Answer 35

changes in the genetic material (DNA)

Question 36

mutagen

Answer 36

agent that causes mutation

Question 37

spontaneous mutation

Answer 37

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

Question 38

base substitution (point mutation)

Answer 38

change in one base

Question 39

silent mutation

Answer 39

no change in the amino acid sequence

Question 40

missense mutation

Answer 40

results in one changed amino acid in the protein sequence

Question 41

nonsense mutation

Answer 41

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

Question 42

frameshift mutation

Answer 42

insertion or deletion of 1 or more nucleotide pairs

Question 43

4 Characteristics of Nuceloside Analogs

Answer 43

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

Question 44

Nucleoside analogs can be useful for _______ & ________.

Answer 44

medicine; research

Question 45

Ionizing radiation (xrays and gamma rays)

Answer 45

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

Question 46

thymine dimers can be repaired by ______ _____ _____

Answer 46

nucleotide excision repair

Question 47

Photolyases

Answer 47

separate thymine dimers

Question 48

constitutive genes

Answer 48

expressed at a fixed rate

Question 49

repressible genes

Answer 49

turn off expression

Question 50

inducible genes

Answer 50

turn on expression

Question 51

repressors

Answer 51

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

Question 52

activators

Answer 52

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

Question 53

operon

Answer 53

a set of coordinately regulated genes that share a single mRNA

Question 54

the lac operon is ______

Answer 54

inducible

Question 55

beta-galactosidase

Answer 55

hydrolyzes lactose into glucose and galactose

Question 56

lactose permease

Answer 56

a membrane protein that transports lactose into the cell

Question 57

The lac repressor is _______ _______.

Answer 57

continually expressed

Question 58

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

Answer 58

operator; promoter

Question 59

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

Answer 59

Allolactose, repressor

Question 60

_____ ___________ binds to the lac promoter and transcription proceeds.

Answer 60

RNA polymerase

Question 61

What accumulates when there is no glucose?

Answer 61

cAMP

Question 62

cAMP binds to the _____

Answer 62

CAP (Catabolic activator protein)

Question 63

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

Answer 63

RNA polymerase; promoter

Question 64

2 transcription differences between eukaryotes and prokaryotes

Answer 64

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