7.2 Factors Affecting Gene Expression

Question 1

define gene expression

Answer 1

making proteins from DNA

Question 2

what is a gene probe

Answer 2

specific bases of DNA that are complementary and have a fluorescent or radioactive tag

Question 3

describe the process of cell differentiation

Answer 3

• stem cells divide
• some genes are inactivated so lose ability to express genes
• some genes are activated so genes are expressed
• activated genes are transcribed to produce mRNA and translated to produce a protein
• protein modifies structure or function of cell

Question 4

how can gene expression be controlled

Answer 4

using transcription factors

mRNA

Question 5

where can gene expression control be targeted towards

Answer 5

transcription stage of protein synthesis

Question 6

how can we stimulate gene expression

Answer 6

1. transcription factors bind to promotor sequence of DNA

2. this stimulates DNA dependent RNA polymerase to bind on and make mRNA

Question 7

describe the process of stimulating or inhibiting gene expression by changing structure of chromatin

Answer 7

1. transcription factor binds to enhancer sequence
2. transcription factor changes chromatin structure to make gene less or more open to DNA dependent RNA polymerase

open=active gene
complementary mediator
or
closed=inactive gene
mediator is not complementary

Question 8

how can spliceosomes control gene expression

Answer 8

1. pre mRNA consists of exon, intron, exon
2. spliceosome cuts out intron
3. spliceosome leaves behind mature RNA made of spliced exons

Question 9

what is the effect of spliceosomes

Answer 9

changing the order of exons which changes order of amino acids
more than one type of mature RNA is made from one gene so different proteins can be made and so different phenotypes

Question 10

what is epigenetics

Answer 10

control of gene expression by things other than base sequences

Question 11

give examples of epigenetics

Answer 11

DNA methylation
histone modification
non-coding RNA