Protein synthesis

Question 1

Transcription: Elongation

Answer 1

• RNA polymerase 2 adds nucleotides to mRNA strand in complementary way

Question 2

Transcription: Termination

Answer 2

• RNA polymerase 2 would dettach from template strand and DNA strand forms helix again

Question 3

Transcription: Initiation

Answer 3

• DNA strands separate to be used as a template strand to form mRNA
• Transcription factors bind to promoter region, which causes separation of DNA strands
• RNA polymerase 2 binds to transcription factors at promoter region
• Causes the separation of DNA strands
• Transcription factors assist polymerase 2 to move down the template strand as it produces mRNA
• Replication occurs in downstream direction (5’ to 3’)

Question 4

Pre-mRNA after termination

Answer 4

• 5’ cap attached to 5’ prime end of pre-mRNA
• Poly A - tail: made up of many Adenines which would be added to 3’ end
• Introns mixed with Exons
• Introns are cut out, Exons are brought together to form continuing coding segments

Question 5

Process of removing Introns

Answer 5

• Specific nucleotides that splicesome would recognize and bind to
• Splicesome: made up of small nuclear ribonucleoproteins that that are combined with other proteins
• Splicesome recognises sequences of nucleotides within intron and cuts out those particular sections and brings together the exons
• Process results in functional mRNA

Question 6

Translation: Initiation

Answer 6

• Association between anitcodon and codon
• GTP converted to GDP
• Energy used to connect large ribosomal subunit to form translation-initiation complex
•

Question 7

Translation: Elongation

Answer 7

• tRNA carried amino acid to P-site
• GTP converted to GDP
• Energy used for movement of polypeptide chain
• A - site tRNA forms polypeptide bind with tRNA on P-site tRNA
• GTP converted to GDP. Energy used for movement of mRNA strand
• tRNA on A site moves to P-site, tRNA on P-site moves to E-site

Question 8

Translation: Termination

Answer 8

• Stop codon on mRNA signals the completion of the formation of polypeptide chain
• Release factor now present on A-site
• Polypeptide moves from tRNA on P-site to release factor on A-site
• H2O in release factor causes the dissociation of polypeptide chain from tRNA on P-site
• 2GTP converted to 2GDP
• Causes the dissociation of translation complex