Chapter 19

Question 1

What is homologous recombination

Answer 1

Involves exchange of identical or similar dna segments between homologous chromosomes

Question 2

What are some examples of mutations

Answer 2

Changes in chromosome structure and number of
Changes in dna of a single gene

Question 3

What is a point mutation

Answer 3

Change in a single base pair and can involve a base substitution

Question 4

What is a transition

Answer 4

Change of a pyrimidine to another pyrimidine or purine to another purine

Question 5

What is a transversion

Answer 5

Change of a pyrimidine to a purine and vice versa

Question 6

True or false: transversions are more common than transitions

Answer 6

False other way around

Question 7

What is a silent mutation

Answer 7

Substitutions that don’t alter amino acid sequence of the polypeptide

Question 8

What is a missense mutation

Answer 8

When an amino acid is changed into a different amino acid

Question 9

Nonsense mutations

Answer 9

Change a normal codon to a stop codon

Question 10

What is a frame shift mutation

Answer 10

Involves deletion or addition of nucleotides that mess up the reading frame

Question 11

What do up and down promoter mutations do

Answer 11

Up promoters increase transcription
Down promoters decrease transcription

Question 12

What is a forward mutation and what is a reverse mutation

Answer 12

Forward is a change in the wild type into some new variation
Reverse mutation changes mutant allele back to wild type (also known as reversion)

Question 13

What is a deleterious mutation and what is a beneficial mutation

Answer 13

Deleterious decreases the chances of survival
Beneficial enhances survival or reproductive success of an organism

Question 14

What are conditional mutations

Answer 14

Affect phenotype only under defined set of conditions

Question 15

What do suppressor mutations do

Answer 15

Reverse phenotypic effects of another mutation
Also called second sight mutations

Question 16

What is an intragenic suppressor

Answer 16

When the second mutation is within the same gene as the first mutation

Question 17

What is an INTERgenic suppressor

Answer 17

Second mutation is in a different gene than the first

Question 18

How does a redundant function work in intergenic suppressors

Answer 18

First mutation inhibits the function of a protein and the second alters a different protein to out that function

Question 19

What is a common pathway in intergenic suppressors

Answer 19

A mutation that causes a defect in one enzyme may be compensated for by a mutation that increases the function of a different enzyme in the same pathway

Question 20

What is a multimeric protein in an intergenic suppressor

Answer 20

Mutation in gene encoding one protein that inhibits a function may be suppressed by a mutation in a gene that encodes for a different subunit

Question 21

What is a transcription factor in an intergenic suppressor

Answer 21

First mutation causes loss of function of a particular protein
Second mutation may cause it to activate the expression of another gene which can compensate for the loss of function caused by the first mutation

Question 22

What is a position effect

Answer 22

When the expression of a gene may be altered because of its new location

Question 23

What are germ line cells and what are somatic cells

Answer 23

Germ line cells are Cells that give rise to gametes such as eggs and sperm
Somatic cells are everything else

Question 24

What are germ line mutations and what are somatic mutations

Answer 24

Germ line are those that occur directly in a sperm or egg cell or in a precursor cell
Somatic are those that occur directly in a body cell not part of the germ line

Question 25

How does size of patching relate to somatic mutations

Answer 25

The earlier the mutation the larger the patch

Question 26

What is genetic mosaic

Answer 26

An individual with somatic regions are genotypically different from the rest of the body

Question 27

What are spontaneous mutations

Answer 27

Result from abnormalities or errors in dna replication

Question 28

What are induced mutations

Answer 28

Caused by environmental agents

Question 29

What are mutagens

Answer 29

Agents that are known to alter dna structure

Question 30

What is depurination

Answer 30

Removal of a purine
Apurinic sites can be repaired but if it fails a mutation may result during dna replication because polymerase will add a random base

Question 31

What is deamination of a cytosine

Answer 31

Removal of an amino group from cytosine base

Question 32

Why do methylated cytosines create hot spots for mutation

Answer 32

Because 5 methyl cytosine can be deaminated to thymine and repair enzymes cannot determine which of the two bases on the dna strand is incorrect

Question 33

What is a tautomeric shift

Answer 33

Temporary change in base structure
Common stable form of thymine and guanine is the keto form
Common stable form of adenine and cytosine in the amino form

Question 34

What do aerobic organisms produce

Answer 34

Reactive oxygen species which include hydrogen peroxide, superoxide, and hydroxyl radical

Question 35

What is oxidative stress

Answer 35

Imbalance between production of ROS and an organisms ability to break them down

Question 36

What can ROS accumulation lead to

Answer 36

Oxidative dna damage

Question 37

What are tri nucleotide repeat expansion mutations

Answer 37

Mutations caused by hair pin loop during replication
There is suggestion that TRNE can occur more frequently in oogenesis and spermatogenesis depending on the gene which is known as anticipation

Question 38

How can a hair pin form in a TNRE

Answer 38

There is at least one C and G
Hairpin leads to increase or decrease in length