Protein Synthesis

Question 1

Why do we use mRNA for protein synthesis rather than DNA?

Answer 1

DNA is a large molecule and so it would be unable to leave through the nuclear pores, however mRNA is much smaller and so is able to do so.

Question 1

What are the steps for the process of Transcription?

Answer 1

1. RNA polymerase unwinds and unzips gene, breaking H bonds between complementary base pairs.
2. Free RNA nucleotides pair with the exposed bases.
3. RNA Polymerase joins up RNA nucleotides by forming phosphodiester bonds, making mRNA
4. mRNA leaves nucleus through nuclear pores to go to ribosome for translation.

Question 2

What are the steps for the process of Translation?

Answer 2

1. mRNA binds to ribosome.
2. tRNA with a complementary anticodon and a specific amino acid binds to mRNA’s codon.
3. another tRNA with the same qualities binds to the next complementary codon.
4. The first amino acid binds to the second amino acid through a peptide bond catalysed by peptidyl transferase.
5. Ribosome moves along mRNA, tRNA leaves to find another specific amino acid.

Question 3

What is peptidyl transferase?

Answer 3

It is an enzyme found in the ribosome which catalyses the bonding between amino acids brought by tRNA.

Question 4

Outline how the organelles in pancreatic cells work together to produce and release these protein molecules
from the cells.

Answer 4

1 nucleus, contains gene (for protein) / site
of transcription / produces mRNA ;
2 ribosomes / rough endoplasmic
reticulum / RER, site of, protein synthesis
/ translation ;
3 vesicles for transport (of protein) ;
4 Golgi (apparatus / body), processes /
modifies / (re)packages, proteins ;
5 (vesicles) fuse to, cell surface / plasma,
membrane ;