Lecture #11

Question 1

How can mutations arise?

Answer 1

spontaneously, as a result of DNA synthesis

Question 2

What happens when the wrong base pairs are paired by stay due to wobble?

Answer 2

a transition mutation occurs at the next round of DNA replication

Question 3

What does depurination lead to?

Answer 3

base substitution

Question 4

What is deamination?

Answer 4

loss of an amino group which changes the type of base pair

Question 5

What are somatic mutations?

Answer 5

mutations that affect the individual but will not be passed on

Question 6

What are germ-line mutations?

Answer 6

mutations that will be passed on

Question 7

What does strand slippage lead to?

Answer 7

Insertions or deletions

Question 8

What happens if chromosomes misalign during crossing over?

Answer 8

unequal crossing over produces insertions or deletions

Question 9

What are the two groups of chemical mutagens?

Answer 9

mutagenic only to replicating DNA or mutagenic to both replicating and non-replicating DNA

Question 10

What are base analogues?

Answer 10

Compounds that mimic nucleotide base pairs

Question 11

How do base analogues affect DNA?

Answer 11

base analogues can become incorporated into DNA which leads to mispairing and transition mutations

Question 12

What do oxidative radicals do to DNA?

Answer 12

Damage DNA by chemical changes to nucleotides

Question 13

What effects do X-rays have on DNA?

Answer 13

can induce chromosome breaks, fusions and translocation

Question 14

How does UV light effect DNA?

Answer 14

Absorption of UV energy by pyrimidines leads to their dimerization, which leads to distortion of the DNA strand

Question 15

What effects do acridines have on DNA?

Answer 15

Acridines intercalate between adjacent base pairs and distort the double helix

Question 16

What are transposable elements?

Answer 16

a transposable elements insert themselves into the DNA and interrupt coding sequences

Question 17

How is sickle cell anemia caused?

Answer 17

a single base pair change in the beta globin gene

Question 18

What do mutations that affect non-coding regions do?

Answer 18

Interfere with promotor function to prevent or reduce transcription, or prevent or reduce translation

Question 19

What is myotonic dystrophy type 1?

Answer 19

CTG expansion in the untranslated region (UTR) of an mRNA transcribed from chromosome 19 encoding an enzyme (kinase)

Question 20

What is myotonic dystrophy type 2?

Answer 20

CTG expansion in an intron of a gene on chromosome 3encoding a zinc finger transcription factor

Question 21

What makes an allele dominant or recessive?

Answer 21

Dominant mutation, loss of function mutation, dominant negative mutation, or gain of function mutation

Question 22

What is a null allele?

Answer 22

A complete loss of function in the recessive allele

Question 23

What is a hypomorphic allele?

Answer 23

a partial loss of function in the recessive allele

Question 24

What is a dominant mutation in an allele?

Answer 24

involve a loss OR gain of gene function

Question 25

What is a loss of function mutation in an allele?

Answer 25

for the genes in which one copy is not enough

Question 26

What is a dominant negative mutation?

Answer 26

a loss of function mutation that interferes with the normal function of the wild type allele

Question 27

What is a gain of function mutation?

Answer 27

enhances the normal function of the gene or causes the expression of the gene in the novel cell type

Question 28

What is the antennapedia mutation in drosophila?

Answer 28

A dominant gain of function mutation in a regulatory region of the Antp gene

Question 29

What is a missense mutation?

Answer 29

a point mutation in which a single nucleotide change results in a codon that codes for a different amino acid

Question 30

What is a nonsense mutation?

Answer 30

a point mutation in which a single nucleotide change results in a premature stop codon

Question 31

What is a frameshift mutations?

Answer 31

When a nucleotide insertion or deletion changes the reading frame of the DNA sequence

Question 32

What is an expanding mutation?

Answer 32

A duplication mutation that repeats every generation (ex: gen 1 would have 1 duplication, gen 2 would then have 2 and so on)