Gene Expression 1

Question 1

What are the two ways genes can be expressed?

Answer 1

• constitutively expressed (always on)

- conditionally expressed (inducible)

Question 2

What are the different ways that gene expression can be controlled?

Answer 2

1. transcription control (main way)
2. RNA processing control
3. RNA transport and localisation control
4. Translation control
5. mRNA degradation control
6. protein activity control

Question 3

What happens if there is a large abundance of a type of RNA in a cell?

Answer 3

there will be a large amount of the protein type that it produces (although not necessary true)

Question 4

For transcriptional control, what is the mRNA population regulated by?

Answer 4

• which genes are transcribed
• the rate at which they are transcribed
• the transcriptional start site used

Question 5

How do you get from pre-mRNA to mRNA?

Answer 5

• splicing (removal of introns)
• capping (addition of 5’ methyl cap
• polyadenylation (addition of 3’ poly(A) tail)

Question 6

What carries the splicing factors?

Answer 6

RNA polymerase which carries the spicing factors

Question 7

What are features of an intron?

Answer 7

• conserved sequences at intron-exon boundaries

- most introns contain STOP codons in all reading frames

Question 8

What is an snRNP?

Answer 8

small nuclear ribonucleic particle

Question 9

What is the role of snRNPs?

Answer 9

to recognise intron-exon boundaries

Question 10

What are the different ways of alternative splicing?

Answer 10

1. alternative selection of promoters
2. alternative selection of cleavage/polyadenylation sites
3. intron retaining mode
4. exon cassette mode