2/27 Gene Mutations

Question 1

true or false

We are all mutants

Answer 1

true

Question 2

what is a mutation

Answer 2

it is a heritable change in a gene that is passed on to subsequent generations

Question 3

If a nucleotide changes and is then repaired before DNA replication, is it a mutation

Answer 3

no, it must be heritable and be passed on

Question 4

what is the beneficial aspect of mutations

Answer 4

they provide evolutionary changes

Question 5

what is the negative aspect of mutations

Answer 5

they can cause disease

Question 6

are all mutations good or bad

Answer 6

sometimes they can have no effect

Question 7

what determines whether a mutation is good or bad

Answer 7

the selective pressure of the corresponding environment

Question 8

What are single gene mutations

Answer 8

point mutations in DNA structure that occur within a particular gene

Question 9

what are chromosome mutations

Answer 9

changes in chromosome structure

• gain, deletion, translocation, inversion

Question 10

what are genome mutations

Answer 10

changes in chromosome number

Question 11

What is a point mutation

Answer 11

it is a change to a nucleotide, it can be a substitution, insertion or deletion

Question 12

What is a base substitution

Answer 12

it is when one nucleotide is swapped for another

Question 13

what is an indel? what does it cause

Answer 13

an indel is an insertion or a deletion, it can cause frameshifts in the reading frame in the ribosome

Question 14

are frameshifts always detrimental?

Answer 14

No, sometimes they can occur in non-coding areas where there is no consequence because it is not being read

Question 15

what are the two types of base substitutions

Answer 15

transition and transversion

Question 16

what is a transition base substitution

Answer 16

it is when there is a change within the same category of nucleotide

pyrimidine-> pyrimidine (T–> C)
purine-> purine (G-> A)

Question 17

what is a G—>A substitution

Answer 17

transition

Question 18

what is a C—> T substitution

Answer 18

transition

Question 19

what is a transversion substitution

Answer 19

it is when the nucleotide is changed to a different category

pyrimidine–>purine (T—> A)

Question 20

what type of substitution is C—> G

Answer 20

transversion

Question 21

what occurs more commonly in nature? transition or transversion substitution

Answer 21

transitions occur in nature since they have a gentle mutation and have less of an effect on the DNA structure

Question 22

Why is the ratio of transition to transversion (2:1) when there are more ways to transvert?

Answer 22

transition mutations keep the DNA structure uniform in its diameter.

Transversions will change the shape into an unfavorable conformation

Question 23

with a transition, a purine/purine change or pyrimidine/pyrimidine change is more likely to result in what type of amino acid?

Answer 23

the same, usually these changes do not change the amino acid (silent mutation)

Question 24

what is the lowest level of impact in point mutations

Answer 24

when the mutation occurs in a noncoding region or a non exon reading

Question 25

true or false, every mutation has a substantial effect

Answer 25

false, some mutations may be in non exon genes

Question 26

what is a silent mutation

Answer 26

it is a point mutation that results in the same amino acid

Question 27

is a silent mutation considered neutral?

Answer 27

no, neutral refers to a type of missense mutation where the amino acid changes but there is no effect

Question 28

what is a missense mutation

Answer 28

it is a point mutation where the amino acid gets changed

Question 29

how do missense mutations affect polypeptides?

Answer 29

they affect the structure and function

Question 30

how would an missense mutation that changes a hydrophobic amino acid to another hydrophobic amino acid affect the resulting polypeptide?

Answer 30

it would have a neutral affect

Question 31

how would an missense mutation that changes a hydrophobic amino acid to a hydrophillic amino acid affect the resulting polypeptide?

Answer 31

it would likely have a drastic affect

Question 32

silent mutations are due to

Answer 32

the degeneracy of codons

Question 33

what is a nonsense mutation

Answer 33

it is a point mutation where a base substitution results in a stop codon

Question 34

what happens if a nonsense mutation occurs near the N terminal

Answer 34

this results in a non functional protein that was terminated too early

Question 35

what happens if a nonsense mutation occurs near the C terminal

Answer 35

this may result in a functional protein as the rest may be fine

Question 36

what is a frameshift mutation

Answer 36

the insertion/deletion of 1,2 or 4+ nucleotides which changes how subsequent nucleotides are read

Question 37

if we insert 3 or 6 nucleotides, how does it affect the reading frame

Answer 37

there is no affect because the reading frame is always read in 3s, by adding another set of 3, the regular amino acids are read correctly but the new 3 add a new amino acid

Question 38

a frameshift near the N terminus will result in

Answer 38

a non functional protein

Question 39

a frameshift near the C terminus will result in

Answer 39

it may be functional still

Question 40

heritable changes must occur in

Answer 40

DNA, they must be passed on

Question 41

will a mutation be detected by polymerases as errors?

Answer 41

no, they will be read and transcribed as usual

Question 42

are RNA changes mutation?

Answer 42

no, changes in RNA is RNA editing and these are not inheritable and cannot be passed down

Question 43

can gene mutations outside the coding sequence affect the phenotype

Answer 43

yes, mutations in regions like the promoter can alter how much the gene is expressed but may not change the shape of the polypeptide itself

Question 44

what occurs if a regulatory element is mutated

Answer 44

the gene cannot be regulated properly and the amount of gene expression will be affected

Question 45

what occurs if a 5'UTR or 3"UTR is mutated

Answer 45

the mRNA may not be able to be translated efficiently; effects gene expression quantities

Question 46

what if a splice site is mutated

Answer 46

the introns will remain and mRNA may not be able to be spliced properly

Question 47

true or false; in order to affect gene expression, every mutation must occur in an exon

Answer 47

false, it can be outside the exon

Question 48

true or false; if you have a mutation, it must affect gene expression

Answer 48

false, the mutation may be in a non-translated region

Question 49

what is a deleterious mutation

Answer 49

it is a mutation that decreases the chances of survival

Question 50

what is a beneficial mutation

Answer 50

it is a mutation that enhances the survival or reproductive success of an organism

Question 51

what is a conditional mutation

Answer 51

it is a mutation that only affects the phenotype under specific conditions

Question 52

If you have a mutation that causes a protein to denature at high heat but is normal at low temperatures, what type of mutation is it

Answer 52

it is a conditional mutation

Question 53

what is a wildtype

Answer 53

it is the most commonly found genotype

Question 54

what is a forward mutation

Answer 54

it is a mutation that changes the wild type to some variant

Question 55

what is a reversion mutation

Answer 55

it is a second mutation that changes the mutant back to the wild-type form

Question 56

What is the difference between a reverse mutation and a reversion mutation

Answer 56

a reverse mutation is where the mutation changes back to the wild-type in exactly the same method that it changed originally a reversion is a mutation that could occur anywhere by any means that leads back to the wild-type

Question 57

what is a supressor mutation

Answer 57

it is a second mutation that counteracts the first , this is a type of reversion mutation since it brings it back to normal

Question 58

What are the two types of suppressor mutations

Answer 58

intragenic and intergenic

Question 59

what is a intragenic mutation

Answer 59

it is a secondary mutation that occurs within the same gene

Question 60

what is a intergenic mutation

Answer 60

it is a secondary mutation that occurs in a different gene

Question 61

if a reversion mutation occurs within the sme gene, what type of suppressor is it

Answer 61

it is a intragenic supression

Question 62

What is an example of an intergenic suppressor mutation restoring enzymatic function?

Answer 62

If a mutation causes the loss of enzymatic function, a second mutation in a different protein may allow it to carry out the lost function.

Question 63

A mutation in an enzyme responsible for converting an intermediate into a product results in reduced product formation. A second mutation in a different enzyme allows product formation to return to normal levels. What type of mutation is the second one?

Answer 63

Intergenic, because a different enzyme is compensating for the original mutation

Question 64

A mutation disrupts the active site of an enzyme, leading to loss of function. A second mutation in the same gene restores enzymatic activity. What type of mutation is this?

Answer 64

Intragenic, because the second mutation corrects the functional defect within the same gene

Question 65

You have a mutation first in gene 1, and then have a mutation at a later date in gene 2. If these two genes do not interact with eachother (independent from each other), then the second mutation can't be considered a reverse mutation true or false

Answer 65

true

Question 66

if you have a second mutation in the same gene, but it does not revert it back to wild type (normal function), then this can't be considered a reverse mutation true or false

Answer 66

true

Question 67

what is a somatic cell

Answer 67

they are body cells

Question 68

if a mutation occurs in a somatic cell, will that mutation be passed onto the individuals offspring?

Answer 68

no, it must occur in the gametes to be passed on

Question 69

if a gamete cell is mutated, will that mutation be passed on to subsequent offspring

Answer 69

yes

Question 70

if a somatic cell is mutated earlier on in development, what is the impact of the mutation in comparison to a mutation that occurs later in a individuals life?

Answer 70

the impact will be greater as more somatic cell generations will be affected by it