Mutation and Plasmids

Question 1

Can switch back and forth between keto and enol structure when incorporated into DNA

Answer 1

5-bromouricil (BU)

Question 2

Three-ring structure with the same shape and size as a base pair

Answer 2

Ethidium bromide

Question 3

Causes double-strand breaks in the DNA backbone

Answer 3

Highly Ionizing Radiation

Question 4

Causes oxidative deamination of amino groups to keto groups which changes the base pairing properties of the modified base

Answer 4

Nitrous acid

Question 5

Adds an alkyl group to N-7 on purine ring resulting in depurination

Answer 5

(EMS) Ethyl Methane Sulfonate

Question 6

Activates the SOS repair system

Answer 6

UV light

Question 7

Can cause cyclobutane pyrimidine dimers and (6-4) photoproducts

Answer 7

UV light

Question 8

Chemical mutagen that reacts with cytosine and converts it to a form that pairs with “A”

Answer 8

Hydroxylamine

Question 9

RecA protein plays a role in this repair mechanism

Answer 9

SOS repair

Question 10

LexA protein prevents transcription of this repair systems genes until induction occurs

Answer 10

SOS repair

Question 11

Invokes production of error-prone DNA polymerases during replication

Answer 11

SOS repair

Question 12

Determines which strand to repair by the degree of base methylation on each strand

Answer 12

Mismatch repair

Question 13

Amino acid substitution that does not change the structure of the protein

Answer 13

Neutral mutation

Question 14

Change in a single DNA base

Answer 14

Point mutation

Question 15

Mutation in a gene that results in mutations occuring in other genes on the chromosome

Answer 15

mutator gene

Question 16

Mutant tRNA that can recognize 2 different codons

Answer 16

Missense suppressor

Question 17

Mutation that alters the reading frame of mRNA resulting in abnormal AA sequence

Answer 17

Frame shift mutation

Question 18

Physical or chemical agent that causes mutation

Answer 18

mutagen

Question 19

Change in a base sequence that prematurely terminates the polypeptide during translation

Answer 19

nonsense mutation

Question 20

tRNA with the wrong amino acid attached to it

Answer 20

mischarged tRNA

Question 21

Activates an alternative metabolic pathway that eliminates the original mutation

Answer 21

Bypass supressor

Question 22

Alteration of DNA structure that can be caused by some antibiotics

Answer 22

Crosslinking

Question 23

Steric requirements at third position in the codon are less stringent for translation

Answer 23

Wobble Hypothesis

Question 24

A mutant that exhibits reduced enzymatic activity

Answer 24

Leaky Mutation

Question 25

Can perform error-prone synthesis across lesions on ds-DNA

Answer 25

DNA polymerase V

Question 26

How would you isolate a spontaneous E. coli mutant that cannot synthesize its own valine? Describe the plating method you would need to utilize.

Answer 26

Plate E. coli on a valine-containing plate and replicate the plate onto a non-valine plate using a stamp. By comparing the two plates, you will be able to tell that the colonies that do not form on the non-valine plate correlate to the Val- colonies that did grow on the valine-containing plate.

Question 27

Nonconjugative mobilized plasmid transferred by conjugative plasmid

Answer 27

Donation

Question 28

Plasmid that only has genes for effective contact

Answer 28

Conjugative plasmid

Question 29

High copy number plasmid

Answer 29

Relaxed plasmid

Question 30

Plasmid that contains antibiotic resistant genes

Answer 30

R plasmid

Question 31

Identification gene on transferred plasmid to indicate transconjugants (phenotypic expression)

Answer 31

Selected Marker

Question 32

Formation of a functional plasmid in a recipient cell

Answer 32

Repliconation

Question 33

Plasmids transferred and maintained in a large number of bacterial species

Answer 33

Broad host range plasmid

Question 34

Bacterial plasmid that can integrate into plant cell DNA

Answer 34

Ti plasmid

Question 35

Plasmid containing genes for proteins which kill closely relates strains

Answer 35

Col plasmid

Question 36

Protein that controls the plasmid copy number in a bacterial cell

Answer 36

Rep protein

Question 37

Closely related plasmids cannot be maintained in the same cell

Answer 37

plasmid incompatibility

Question 38

List 5 basic features of plasmids

Answer 38

1. Extrachromosomal circular DNA molecules
2. Found in most bacteria, some eukaryotic cells (yeast)
3. Have own genes for regulating time of synthesis
4. Dependent on host metabolism for replication
5. Contain essential genes for certain situations (antibiotic resistance)

Question 39

What are the 4 basic steps of the transfer process for bacterial conjugation?

Answer 39

1. Effective contact (donor-recipient pair)
2. Mobilization (prepare DNA for transfer)
3. DNA transfer
4. Repliconation - formation of a functional plasmid in recipient cell

Question 40

In the conjugation experiment, what is the selected marker gene and what is the counter-selected marker gene for the mating? What is the purpose of the counter-selected marker gene?

Answer 40

Selected marker gene - the Lac+ plasmid that was given to the recipient by the donor through conjugation.Counter-selected marker gene - The streptomycin resistant (Str^r) gene carried by the recipient. This is visible after plating both on antibiotic and Lac+ agar as cellular proliferation of recipient cells only.