PMG Final Flashcards Preview

Prokaryotic Molecular Genetics > PMG Final > Flashcards

Flashcards in PMG Final Deck (88):
1

A mutation always causes a mutant phenotype. T or F

Fasle

2

A messenger is 336 nucleotides long, including the initiator and termination codons. The number of amino acids in the protein translated from this mRNA is

111

3

A spontaneous mutation usually originates as an error in

DNA replication

4

A ____ mutation affects the phenotype only under certain conditions.

conditional

5

Changing the codon AGC to AGA represents a ____ mutation.

nonsense

6

A point mutation that changes a codon specifying an amino acid into a stop codon is called a

nonsense

7

The enzyme that creates a short RNA oligonucleotide at initiation sites where replication is to be carried out is
called

Primase

8

Gram-negative: have double cell membrane. T or F

True

9

Nucleotides in each strand are linked by 5’-3’ phosphodiester bonds. T or F

true

10

DNA synthesis on the lagging strand is continuous. T or F

False

11

n the lagging during the DNA synthesis the Okasaki fragments are synthesized. T or F

True

12

Bacteria have one circular chromosome, main genome (which carries housekeeping genes). To or F

True

13

The replication of the bacterial chromosome is unidirectional

False

14

What relaxes strands

topoisomerase or girase

15

What opens strand and acts as guide for primase on both strands

Helicase

16

What keeps the strands apart during the replication process

Single binding proteins

17

What synthesizes primer sequences that are used by DNA polymerase III

Primase

18

What extends strands only in 5’ 3’ direction, thus one strand is continuous and one is in short
fragments (Okazaki fragments)

DNA Polymerase 3

19

Replication continues until the replication fork enters a region of the chromosome called

Ter

20

Partitioning of the chromosome: is the distribution of one daughter chromosome to each of the two daughter cells. T or F

True

21

RNA which is able to pick up a specific amino acid, transfers it to ribosomes

tRNA

22

is synthesized complementary to a gene and subsequently translated into a polypeptide or protein at ribosomes

mRNA

23

Below is the schematic representation of _______. Indicate the function its sub-units (show it below)

RNA polymerase

24

Promoter is a nucleotide sequence up stream of the gene to which RNA polymerase binds at the initiation of transcription. T or F?

True

25

___ is where an aminoacyl-tRNA first attaches

site A or acceptor or aminoacyl site

26

The peptide bond is formed by a ribozyme, called

peptidyl transferase

27

___ is where the growing amino acid chain is temporarily being held by a tRNA as the next codon in the mRNA is being read.

site P or peptide site

28

____ Break the covalent bond that holds the finished protein to the terminal tRNA.

Release factors

29

Sec YEG : proteins that assist the non-covalent folding/unfolding. T or F

True

30

Which mRNA codes for the following polypeptide?
met arg ser leu glu
a) 3'-AUG CGU AGC UUG GAG UGA-5'

b) 3'-AGU GAG GUU CGA UGC GUA-5'

c) 5'-AUG CGU AGC UUG GAG UGG-3'

d) 1'-AUGCGUAGCUUGGAGUGA-3'

e) 3'-AUGCGUAGCUUGGAGUGA-1'

c) 5'-AUG CGU AGC UUG GAG UGG-3'

31

What is the consequence of a nonsense mutation?

Introduces a stop codon

32

A transition is a point mutation in which a purine is replaced by the other purine (A for G or G for A) or a pyrimidine by the other pyrimidine (C for T or T for C). A transversion is a point mutation in which a pyrimidine is replaced by a purine or vice versa. Some point mutagens (mutagenic chemicals that cause point mutations) mainly cause transitions or mainly transversions or mainly frameshift mutations.


Gene A contains a frameshift mutation. To revert that mutation (change it back to normal or wild type) you would use a

Mutagen causing frameshifts

33

A transition is a point mutation in which a purine is replaced by the other purine (A for G or G for A) or a pyrimidine by the other pyrimidine (C for T or T for C). A transversion is a point mutation in which a pyrimidine is replaced by a purine or vice versa. Some point mutagens (mutagenic chemicals that cause point mutations) mainly cause transitions or mainly transversions or mainly frameshift mutations.


To revert a transition mutation you would use a

mutagen causing transitions

34

A transition is a point mutation in which a purine is replaced by the other purine (A for G or G for A) or a pyrimidine by the other pyrimidine (C for T or T for C). A transversion is a point mutation in which a pyrimidine is replaced by a purine or vice versa. Some point mutagens (mutagenic chemicals that cause point mutations) mainly cause transitions or mainly transversions or mainly frameshift mutations.


To revert a transversion mutation you would use a

mutagen causing transversions

35

The lac operon is expressed when

glucose is low and lactose is absent.

36

When in a complex with ________, the CAP protein binds to the CAP site and ________ the expression of the lac

operon

cAMP ; switches on

37

In the absence of lactose, the lac repressor is

active and can bind to the operator.

38

The inducer of the lac operon is an isomer of lactose. T or F

TRUE

39

When RNA polymerase is bound to the lac promoter sequence, transcription of the lac operon is on. T or F

True

40

The trp operon consists of ________ structural genes.

five

41

In the absence of tryptophan, the trp repressor is

inactive and cannot bind to the operator.

42

In the presence of tryptophan, tryptophan binds to the

trp repressor.

43

In the presence of tryptophan, transcription of the trp operon is on. T or F

False

44

An operon is a group of genes that is under the control of a single operator site. T or F

False

45

Cells of an E. coli strain that are trp - lac Z- met+ bio+ were mixed with cells of an E. coli strain that are trp + lac Z + met- bio- and cultured for several hours. Then cells were removed, washed, and transferred to minimal media containing
lactose as the only sugar source. A few cells were able to grow on minimal media with lactose, and formed colonies. How
did these few cells become trp+ lac+ Z met+
bio+ ?

Conjugation

46

How many lac Z genes were present in the cells described in the previous problem (11) that were able to grow on minimal media?

Cells of an E. coli strain that are trp - lac Z- met+ bio+ were mixed with cells of an E. coli strain that are trp + lac Z + met- bio- and cultured for several hours. Then cells were removed, washed, and transferred to minimal media containing
lactose as the only sugar source. A few cells were able to grow on minimal media with lactose, and formed colonies. How
did these few cells become trp+ lac+ Z met+
bio+ ?

Two, the lac Z- allele on the bacterial chromosome and the lac Z+ allele on the F' episome.

47

How would you describe the regulation of lactose metabolism in the cells described in problem 11 that were able to grow on minimal media with lactose as a nutrient?


Cells of an E. coli strain that are trp - lac Z- met+ bio+ were mixed with cells of an E. coli strain that are trp + lac Z + met- bio- and cultured for several hours. Then cells were removed, washed, and transferred to minimal media containing
lactose as the only sugar source. A few cells were able to grow on minimal media with lactose, and formed colonies. How
did these few cells become trp+ lac+ Z met+
bio+ ?

normal regulation of lactose metabolism.

48

An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F' plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?

constitutive expression of lac Z+.

49

An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F' plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?

Predict the phenotype of a lacI mutant.

The lac genes would be expressed continuously.

50

An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F' plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?

If a second wild type or normal copy of the lacI gene (just lacI and not lacZ, lacY, or lacA) is introduced into the lacI mutant cell, what would be the phenotype of this partial diploid (also referred to as a merodiploid)?

The lac genes would be expressed efficiently only in the presence of lactose.

51

An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F' plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?

Predict the phenotype of a lacI S or "super-repressor" mutant. A lacI S mutant synthesizes a repressor that cannot bind
to the inducer.

The lac genes would never be expressed efficiently.

52

An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F' plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?

Predict how a lacI S mutant would be affected by the construction of a merodiploid that has a second normal copy of the lacI gene.

The lac genes would never be expressed efficiently.

53

An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F' plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?

Predict the phenotype of an operator mutant (Oc) which would prevent the binding of the repressor.

The lac genes would be expressed continuously

54

An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F' plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?


Predict the phenotype of a promoter mutant (lacP) which has a mutation in the promoter for the lac operon.

The lac genes would never be expressed efficiently.

55

An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F' plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?

Predict the phenotype of a lacZ mutant, which has a mutation in the gene for β-galactosidase.

The production of β-galactosidase would be affected, but other protein products would be unaffected.

56

An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F' plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?


Predict the phenotype of a lacY mutant, which has a mutation in the gene for lactose permease.

The lac genes would be expressed efficiently until the lactose supply in the cell is exhausted.

57

DNA transformation involves the transfer of DNA via

naked DNA in solution

58

When DNA from an ampicillin resistant organism is brought into an ampicillin sensitive organism by transformation
and the product is grown on agar containing ampicillin

only the transformed cells will grow

59

In transformation, both strands of donor DNA enter the recipient cell. T or F

False

60

Donor DNA is combined with recipient DNA by homologous recombination. T or F

True

61

A bacterial cell that is able to take up naked DNA is said to be

competent

62

Which of these describes a similarity between the lac and ara operons?

A) Expression of structural genes does not occur at high glucose concentrations.

B) lacI and araI both encode trans acting factors.

C) Binding of a regulatory protein is prevented in the presence of an inducer.

D) All of these are similarities.

E) None of these are similarities.

A) Expression of structural genes does not occur at high glucose concentrations.

63

Attenuation of the trp operon:

A) Occurs when transcription is complete before translation begins.

B) Is mediated by the trp repressor protein.

C) Occurs in the presence of high levels of tryptophan.

D) All of the above.

E) None of the above.

C) Occurs in the presence of high levels of tryptophan

64

A prophage is

phage DNA integrated into host cell genome

65

One of the largest global regulatory systems in bacteria are

Catabolite-Sensitive Operons

66

CAP contains an "activating region" that has been proposed to participate in direct protein-protein interactions with RNA polymerase and/or other basal transcription factors.

a) in the Lac operon

b) in the Trp operon

c) in all Catabolite-Sensitive Operons

d) in Ara operon

e) in Lac and Ara operons

c) in all Catabolite-Sensitive Operons

67

Some Hsp are chaperones that direct the folding of newly-translated proteins. In heat shock, they bind to denatured proteins and either help to refold them into their inactive conformations or, if the protein is extensively denatured, chaperones target these proteins for destruction. T or F

False

68

_____ protein may be a "cellular thermometer" that senses the change in temperature and induces the transcription of
heat shock genes

DnaK

69

Sigma-32 binds to the RBS of its own mRNA and blocks access of the ribosome. T or F

True

70

Immediately after a temperature increase

a)most of the DnaK will have to help renature unfolded proteins, thus making DnaK unavailable for binding
sigma-32. So free sigma-32 is more stable (less susceptible to protease digestion) and more active.

b) most of the DnaK will have to help renature unfolded proteins, thus making DnaK available for binding sigma-32. So free sigma-32 is less stable (less susceptible to protease digestion) and more active.

c) most of the DnaK will be available for binding sigma-32; therefore bound sigma-32 is more stable (less susceptible to protease digestion) and more active.

a)most of the DnaK will have to help renature unfolded proteins, thus making DnaK unavailable for binding
sigma-32. So free sigma-32 is more stable (less susceptible to protease digestion) and more active.

71

Transcriptional Regulation during the development of a typical large DNA phage the ________________ products are responsible for regulation the transcription (turn on or off the transcription of other genes)

Regulatory

72

In specialized transduction

a) requires a phage that uses the lysogenic cycle for reproduction

b) only certain bacterial genes can be transferred and these genes, as you will see, must exist on either side of the prophage
most of the DnaK will have to help renature unfolded proteins, thus making DnaK unavailable for binding
sigma-32. So free sigma-32 is more stable (less susceptible to protease digestion) and more active.


c) a phage that uses the lytic cycle for reproduction

d) Whatever piece of bacterial DNA happens to get packaged within the phage is the genetic material that will be transferred between cells.

e) A and B

e) A and B

73

The use or alteration of cells or biochemicals to provide a useful product describes

Biotechnology

74

Which of the technologies listed below is a valuable method for mass-producing drugs and other useful proteins?
a) recombinant DNA technology
b) transgenic technology

c) biotechnology
d) gene targeting

a) recombinant DNA technology

75

Manufacturing recombinant DNA molecules involves cutting a gene from its normal location, inserting it into a circular piece of DNA from a bacterial cell, and then transferring the circle of DNA to cells of another species. Which of the tools below is used to cut the gene from its normal location?
a) restriction enzyme
b) plasmid
c) bacteriophage d) vector

a) restriction enzyme

76

Manufacturing recombinant DNA molecules involves cutting a gene from its normal location, inserting it into a circular piece of DNA from a bacterial cell, and then transferring the circle of DNA to cells of another species. Which of the below describe the circular piece of DNA from a bacterial cell?

a) restriction enzyme
b) plasmid
c) bacteriophage
d) vector

B) plasmid

77

Which gene transfer technique involves a tiny needle which is used to inject DNA into a cell lacking that DNA sequence?

microinjection

78

The process of ____ involves the introduction of a gene into a cell where it exchanges places with its counterpart in the host cell.

Gene targeting

79

Genetic engineering manipulates gene products at the level of the

DNA

80

A cDNA version of a gene includes

codons for a mature mRNA.

81

____ are used to select genes of interest from a genomic library.

DNA probes

82

Sequence similarity searching algorithms like BLAST are based on the premise that if two sequences are similar then they are likely to be homologous. T or F

true

83

A motif is a distinctive pattern of amino acids, conserved across many proteins, which gives a particular function to the protein. T or F

True

84

Expression libraries are made with

Complementary DNA (cDNA)

85

To understand the functions of genes we use reverse genetics and some of its tools are a) RNAi
b) Knockout study c) Microarray
d) a and b
e) a, b and c

e) a, b and c

86

Which of the following tools of recombinant DNA technology is INCORRECTLY paired with its use?
a) Restriction endonuclease - production of DNA fragments for gene cloning
b) DNA ligase - enzyme that cuts DNA, creating sticky ends
c) DNA polymerase - copies DNA sequences in the polymerase chain reaction
d) Reverse transcriptase - production of cDNA from mRNA

B) DNA ligase - enzyme that cuts DNA, creating sticky ends

87

The "Southern" technique involves:

The detection of DNA fragments on membranes by a radioactive DNA probe

88

"Gene library" is a term used to describe:

b) Bacteria with plasmids containing DNA fragments representing the majority of the genetic information