DNA - replication and protein synthesis

Question 1

Describe the process of DNA replication.

Answer 1

• DNA helicase breaks hydrogen bonds between complimentary base pairs.
• Each strand acts as a template for free DNA nucleotides to join by complimentary base pairing.
• DNA polymerase forms phosphodiester binds in a condensation reaction, joining the phosphate to the deoxyribose sugar. DNA polymerase works up the leading strand and down the lagging strand.

Question 2

Describe the process of transcription.

Answer 2

• DNA helicase breaks the hydrogen bonds between complimentary base pairs causing gene to unwind.
• Free RNA nucleotides bind with hydrogen bonds to template stand by complimentary base pairing, catalysed by RNA polymerase.
• produced mRNA strand is complimentary to nucleotide base pairing.

Question 3

Describe the process of Translation

Answer 3

• mRNA leaves nucleus through nuclear pore and attaches to a ribosome.
• Ribosome pairs tRNA which has a anticodon that is complimentary to the mRNA codon.
• each tRNA has a specific amino acid.
• ribosome can hold two tRNA at once so moves to next tRNA and catalyses the reaction.
• Amino acids are joined by peptide bonds in a condensation reaction.