Protein synthesis

Question 1

What are the 2 stages of protein synthesis?

Answer 1

Transcription and translation

Question 2

What are the stages of transcription?

Answer 2

1. RNA polymerase breaks the hydrogen bonds and DNA unwinds.
2. Free nucleotides organise with their corresponding base pairs.
   Template stands (ANTISENSE strand) of DNA is transcribed to make mRNA
   This will be the same as the CODING STRAND (apart from T - U).
3. Phosphodiester bonds form along the backbone of the mRNA as in DNA.
4. Only the base sequence for a particular gene is transcribed.
   When finished, the mRNA leaves through the nuclear envelope and the DNA through the nuclear envelope and the DNA zips up.

Question 3

What are the stages of translation?

Answer 3

1. mRNA joins an rRNA molecule at the START CODON.
2. A tRNA molecule, with complementary anticodon for codons on the mRNA, arrives at the ribosome (rRNA + protein = ribosome organelle).
3. Each tRNA molecule brings the associated amino acid attached.
4. When the 2 tRNAs have arrived at the rRNA at a point along the mRNA stand, a peptide bond forms.
5. rRNA moves along to the next codon and the polypeptide chain begins to form.