3.10 Protein Synthesis

Question 1

What is transcription?

Answer 1

The production of an mRNA molecule from a DNA base sequence

Question 2

What happens in transcription?

Answer 2

1. Helicase unwinds and unzips DNA, usually along the base sequence of one gene
2. RNA nucleotides bind to complementary on the template (antisense) strand
3. RNA polymerase joins RNA nucleotides together with phosphodiester binds
4. A stop codon causes RNA polymerase to detach
5. The mRNA molecule detaches from the DNA and leaves the nucleus

Question 3

What is translation?

Answer 3

The production of a polypeptide at ribosomes; the sequence of amino acids is determined by the codons in mRNA

Question 4

What happens in translation?

Answer 4

1. nRNA atta he’s to a ribosome (in a groove between two subunits)
2. The first mRNA codon binds to a tRNA molecule with a complementary anticodon
3. The tRNA is bound to an amino acid specific to its anticodon
4. A sequence tRNA (carrying another amino acid) binds to the adjacent mRNA codon
5. A peptide bind forms between the two amino acids
6. The ribosome continues along the mRNA molecule from codon to codon
7. Amino acids are bonded together in a polypeptide chain until a stop codon is reached
8. The polypeptide is released

Question 5

What is the difference between replication and translation?

Answer 5

During translation only a small section of DNA is unzipped, only one strand acts as a template, RNA polymerase catalysed the reaction instead of DNA polymerase and mRNA is produced instead of a new DNA strand
However they are both unwound and hydrogen bonds between complimentary base are broken