Translation

Question 1

What is translation

Answer 1

The process of producing polypeptides from the sequence of codons on mRNA

Question 2

Ribosomes

Answer 2

Made from rRNA and protein
(Ribonucleoprotein complex)
Non-membrane bound ( found in prokaryotes and eukaryotes )
More than 60% rRNA
Binding site for tRNA
Has a large and small subunit which the mature mRNA strand passes through

Question 3

tRNA

Answer 3

Each tRNA molecule in translation can only bind to and carry one amino acid each
Each tRNA molecule in translation also has one specific anticodon that is complementary to a triplet codon on a mRNA strand

Question 4

Translation stages

Answer 4

Initiation
Elongation
TERMINATION

Question 5

Translation process (Understanding)

Answer 5

1) Ribosomes attaches to the mRNA and moves along until it comes across a start codon (AUG)
2) The tRNA molecule which has a complementary anticodon to the start codon attaches to the ribosome
3) Start codon always codes for the amino acid methionine
4) Ribosome moves along to the next codon two at a time and the process is repeated and each tRNA is released leaving the amino acids as a trail in the ribosome
5) Energy from ATP hydrolysis catalyses formation of peptide bonds between amino acid
6) Ribosomes moves along mRNA forming a polypeptide until a stop codon is reached
7)Polypeptide seperates

Question 6

Describe how a polypeptide is formed in Translation (6 marks ) (Exam questions)

Answer 6

A mRNA molecule attaches to a ribosome OR rough endoplasmic reticulum (1)
tRNA anticodon binds to complementary mRNA start codon (1)
tRNA brings specific amino acid (Methionine) (1)
Ribosome moves along to the next codon so another tRNA molecule can attach (1)
Amino acids join together by peptide bonds with energy form ATP hydrolysis (1)
tRNA released as ribosome moves along mRNA to form polypeptide (1)
Polypeptide released (1)
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