Transcription and RNA Processing

Question 1

What is meant by the central dogma of molecular biology?

Answer 1

• The control of gene expression is fundamental to the development and maintenance of multicellular organisms
• The correct temporal and spatial expression of specific genes governs the identity of a cell and defines its function
• Central dogma:
  DNA - (transcription) -> RNA - (translation) -> Protein
• Multiple steps in this process are subject to control, but by far the most important one is the synthesis of mRNA from the gene, i.e. transcription

Question 2

What is RNA polymerase?

Answer 2

• The enzymes that synthesises RNA from DNA are called RNA polymerases
• RNA is synthesised in the 5’-3’ direction
• DNA template is read in 3’-5’ direction (so only this strand can be used to synthesise RNA in this direction)

Question 3

What are the steps in mRNA synthesis?

Answer 3

1. Initiation – the polymerase binds to the gene
2. Elongation – the polymerase transcribes the gene
3. Termination – the polymerase stops transcribing the gene
4. Processing – pre-mRNA -> the mature RNA is formed
5. Export – the mRNA leaves the nucleus to be translated