Chapter 15

Question 1

What did the Luria-Delbruck Flucation test show?

Answer 1

That mutations occur randomly, and are then subject to selection- they are not adaptive.

Question 2

Explain somatic mutations.

Answer 2

Somatic mutations occur in any cell except germ cells and are NOT heritable.

Question 3

Explain germ-line mutation.

Answer 3

Germ-line mutations occur in gametes and ARE inherited.

Question 4

What is the outcome of a base substitution?

Answer 4

A point mutation

Question 5

What is the outcome if there is an insertion or deletion?

Answer 5

A frameshift mutation.

Question 6

Explain a missense mutation.

Answer 6

A missense mutation is a mutation that changes a codon into a codon that codes for a different amino acid.

Question 7

Explain a nonsense mutation.

Answer 7

A nonsense mutation is a mutation that changes a codon to a stop codon and results in premature termination of translation.

Question 8

Explain a silent mutation.

Answer 8

A silent mutation does not change the protein sequence.

Question 9

What is a transition?

Answer 9

Transitions are pyrimidine replacing a pyrimidine or a purine replacing a purine.

Question 10

What is a trasnversion?

Answer 10

Transversions are a purine and a pyrimidine interchanged.

Question 11

What are purines?

Answer 11

A and G

Question 12

What are pyrimidines?

Answer 12

C, T, and U

Question 13

Mutations are typically classified according to their what?

Answer 13

Their phenotypic effects.

Such as: loss of function, gain of function, morphological, behavioral, nutritional, etc.

Question 14

Mutations can occur spontaneously and it could be due to DNA polymerase inserting incorrect nucleotides. This is generally due to mispairing and a failure to proofread. What does this result in?

Answer 14

Point mutations

Question 15

Explain Tauomeric Shifts.

Answer 15

Tautomeric shifts are shifts in bases that occur spontaneously and can induce mutations.

An example of this is Thymine bonding with Guanine, when it should be bonding with Adenine.

Question 16

What are the most common types of spontaneous mutations?

Answer 16

Depurination and Deamination.

Question 17

Explain depurination.

Answer 17

Depurination is the taking out of a base completely from the backbone, which leads to a frameshift.

Question 18

Explain deamination.

Answer 18

Deamination is the changing of a base spontaneously, like a C changing to a U.

Question 19

What is a mutagen?

Answer 19

Mutagens are natural or artificial agents that induce mutations.

Question 20

What do alkylating agents cause?

Answer 20

Alkylating agents donate an alkyl group to amino/keto groups in nucleotides and alter base-pairing.

Question 21

What do intercalating agents cause?

Answer 21

Intercalating agents cause frameshift via insertion.

Question 22

What does UV light/radiation cause?

Answer 22

Ultraviolet light (UV radiation) creates pyrimidine dimers causing errors to be introduced during DNA replication.

Question 23

Radiation in the form of X-rays and gamma rays are __________.

Answer 23

Mutagenic

Question 24

What is the difference between Duchenne and Beck muscular dystrophy.

Answer 24

Duchenne muscular dystrophy is caused by a frameshift mutation, which Beck muscular dystrophy is caused by a missense mutation.

Question 25

Most DNA polymerases are able to recognize and correct errors in replication, this is known as _______.

Answer 25

Proofreading

Question 26

What are transposons?

Answer 26

DNA elements that can move within and between genomes.. This can cause deletions, duplications, inversions, etc.

Question 27

Transposon mobility by cutting and pasting DNA may be _________ or _________.

Answer 27

nonreplicative or replicative