E7. Translation and protein synthesis

Question 1

what is a gene?

Answer 1

A section of DNA that directs the synthesis of one or more overlapping mature RNA molecules (e.g. mRNA, miRNA, rRNA, tRNA)- there are non-mRNA coding genes

Question 2

how many amino acids are there

Answer 2

20

Question 3

how many amino acids can be encoded? stop codons?

Answer 3

64- 4 to the power of 3
(61 codons, 3 stop codons)

Question 4

what is the start codon which determines the reading frame?

Answer 4

-AUG encoding Met

Question 5

what are the three stop codons ending the reading frame?

Answer 5

UAA, UAG, UGA

Question 6

what does ribosomal RNA (rRNA) do in translation

Answer 6

links amino acids

Question 7

what are the different sites involved in translation? (APE)

Answer 7

A: aminoacyl tRNA site, where aminoacyl tRNA recognises codon
P: peptidyl tRNA site, peptidyl tRNA placement before peptide bond formation
E: where the uncharged tRNA exiting the ribosome is localised
(look on one note)

Question 8

what do aminoacyl tRNAs do?

Answer 8

-Specific aminoacyl tRNA synthetases couple specific amino acids to their own tRNAs
-Aminoacyl tRNAs mediate the translation of codon to amino acid by basepairing
(look one note)

Question 9

what are the three main steps in protein translation?

Answer 9

-Initiation: Finding the start codon and assembling the ribosome with the first tRNAs
-Elongation: Coupling amino acids from tRNAs to a growing peptide chain
-Termination: Recognising the stop codon and releasing the new protein

Question 10

what are the steps of translation elongation?

Answer 10

1. Aminoacyl tRNA binding (codon recognition)
2. Peptidyl transfer (peptide bond formation)
3. Translocation (moving to next codon)

Question 11

what do many antibiotics specifically target?

Answer 11

bacterial protein synthesis machinery