Exam 4 forgotten

Question 1

Common pathway

Answer 1

Two or more different proteins may be involved

mutation causes a defect in one protein can be compensated for by a mutation that alters the function of a different protein in the same pathway

Question 2

Intragenic

Answer 2

First mutation disrupts normal protein function

Suppressor mutation affects the same protein restores function

First mutation inhibits lactose and second restores it

Question 3

Intergenic

Answer 3

First mutation inhibits the function of a protein

Second mutation alters a different protein to carry out the function

Proteins function as an enzyme

Question 4

Multimeric protein

Answer 4

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

Double mutation restores the function

Question 5

Transcription factor

Answer 5

First mutation causes loss of function of a protein

Second mutation may alter a transcription factor and cause it to activate the expression of another gene

Other gene encodes a protein that can compensate for the loss of function caused by first mutation

Question 6

Reverse Mutation

Answer 6

changes mutant allele back to wild type

Question 7

Promoter

Answer 7

may increase or decrease the rate of transcription

Question 8

Regulatory element / operator site

Answer 8

may disrupt the ability of a gene to be properly regulated

Question 9

5’ UTR / 3’ UTR

Answer 9

May alter the ability of mRNA to be translated (may alter mRNA stability )

Question 10

Splice recognition sequence

Answer 10

may later the ability of pre-mRNA to be properly spliced

Question 11

Feedback loop

Answer 11

activation of a gene that encodes a transcription factor

transcription factor continues to stimulate its own expression

Question 12

Localization of histone variants

Answer 12

Histone variants may become localized to specific positions such as near the promoters of genes and affect transcription

Question 13

Covalent histone modification

Answer 13

specific amino acid side chains found in the aminoterminal tails of histones can be covalently modified

They can be acetylated or phosphorylated

modifications may enhance or inhibit transcription

Question 14

Chromatin remodeling

Answer 14

When changes occur in the vicinity of promoters, the level of transcription may be altered

Larger scale changes in chromatin structure may occur (X chromosome inactivation in female mammals)

Question 15

DNA methylation

Answer 15

Methyl groups may be attached to cytosine bases in DNA

When methylation occurs near promoters transcription is usually inhibited