post/pre-translational control

Question 1

define RNA processing

Answer 1

changing the nucleotide sequence of mRNA molecules through base addition, deletion or substitution

Question 2

describe how pre-mRNA is processed to produce mature mRNA and where the process occurs.

Answer 2

• in nucleus
• cap added to 5’ end and tail added to 3’ end - stabilise mRNA and delay degradation in cytoplasm, aids binding to ribosome
• splicing - introns are removed and exons are joined together

Question 3

describe how degradation of mRNA as an example for translational control.

Answer 3

• the more resistant mRNA, the longer it lasts in cytoplasm
• greater quantity of protein synthesised

Question 4

describe binding of inhibitory proteins as an example for translational control.

Answer 4

prevents mRNA from binding to ribosomes and therefore protein synthesis

Question 5

describe regulation of translation initiation factors as an example for translational control.

Answer 5

aid binding of mRNA to ribosomes

Question 6

give an example of regulation of translation initiation factors as an example for translational control

Answer 6

eggs of many organisms produce mRNA - not required until after fertilisation when initiation factors are activated

Question 7

describe the role of protein kinases in regulation of gene expression or protein activity.

Answer 7

• phosphorylation changes tertiary structure + so protein function - can activate them
• important regulators of cell activity
• often activated by cAMP

Question 8

what are protein kinases?

Answer 8

enzymes that catalyse phosphorylation of proteins