6.10

Question 1

Describe the process of transcription including post-transcriptional modifications

Answer 1

• a DNA section is split by DNA helicase
• RNA polymerase binds to the template strand, attaching RNA nucleotides to it via complimentary base pairing
• the new pre-mRNA strand breaks away from the template strand, and the DNA strands bind back together
• pre-mRNA is spliced, where spliceosomes cut out introns (non coding/useful parts) and attach together remaining exons (coding/useful parts) to make the final mRNA strand

Question 2

The human genome contains approximately 25,000 genes but we are able to produce approximately 100,000 different proteins. Explain how post-transcriptional modifications of mRNA enable this number of proteins to be produced

Answer 2

The process of splicing allows for many different versions of mRNA from the same pre-mRNA, due to cutting out and connecting together different exons and introns.