Protein synthesis

Question 1

stages of transcription

Answer 1

1. DNA in the nucleus unwinds
2. hydrogen bonds are broken between the two DNA strands by DNA helicase
3. the template strand is used to construct the mRNA
4. complementary RNA nucleotides join to the template strand and form hydrogen bonds
5. RNA polymerase binds to the DNA and joins the RNA nucleotides together with phosphodiester bonds to form mRNA
6. mRNA is released from the nucleus via a nuclear pore

Question 2

stages of translation

Answer 2

1. in the cytoplasm mRNA attaches to a ribosome
2. the first start codon of the mRNA enters the ribosome
3. a tRNA molecule with complementary anticodon brings the appropriate amino acid
4. the anticodon of the tRNA binds to the codon of the mRNA using hydrogen bonds
5. the ribosome moves along one codon and the next appropriate tRNA with an amino acid binds to the next codon
6. the two amino acids then join with a peptide bond in a condensation reaction
7. the first amino acid detaches from its tRNA
8. the process is repeated and a chain of amino acids if formed
9. the stop codon indicates when the process should stop