session 6-transcription and translation

Question 1

what happens for mature RNA to be synthesised?

Answer 1

-introns are removed by splicing and the exons at either end are joined together

Question 2

how abundant is mRNA percentage wise, what RNA polymerase does it use and how many kinds are there?

Answer 2

• 2%
• RNA polymerase 2
• 100,000 kinds

Question 3

how abundant is rRNA percentage wise, what RNA polymerase does it use and how many kinds are there?

Answer 3

• 80%
• RNA polymerase 1
• very few kinds

Question 4

how abundant is tRNA percentage wise, what RNA polymerase does it use and how many kinds are there?

Answer 4

• 15%
• RNA polymerase 3
• 100 kinds

Question 5

when a tRNA molecule becomes charged (by an attachment of an amino acid) what is it called?

Answer 5

aminoacyl-tRNA

Question 6

where are introns and exons found?

Answer 6

on pre mRNA

Question 7

rRNA has two sites for tRNA to bind to. What are they called and what does each one do?

Answer 7

• P site (holds Peptide chain)

- A site (accepts tRNA)

Question 8

describe the process of translation in 2 steps, referring to the P and A sites

Answer 8

step 1: met-tRNA (begin translation codon) attaches to P site and aminoacyl-tRNA comes along, attached to A site
step 2: methionine forms a peptide bond with aminoacyl-tRNA at A site and tRNA then leaves P site and ribosome because it is now uncharged.
Step 3:petidyl tRNA then trans locates back to P site

Question 9

what enzyme is required for the binding of 2 amino acids?

Answer 9

petidyl transferase

Question 10

what are the 3 steps needed for mRNA maturation?

Answer 10

capping, polyadenyltion, splicing

Question 11

name 3 differences between gene expression in mammalian and bacterial cells

Answer 11

• simpler promoters
• diff transcription factors
• 1 RNA polymerase