Question

Which nucleotide change is the most likely cause of Liam’s disease?

2) Describe how a mutation that creates a premature stop codon would affect the following and why.

a) DNA replication?

b) Transcription?

c) Translation?

3)   Draw replication forks that would result from the absence of the following enzymes (Draw Out)

a) DNA Polymerase

b) Helicase

C) Primase

D) Ligase

Answer 1

Liam disease changes dystrophin protein. The most likely change in the Thymine nucleotide .

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DNA replication DNA from DNA and in transcription level DNA from mRNA. In these processes stop codons ate not involved.

Stop codons involved in the translation process which causes mutation. Nonsense mutation and mis sense mutation occurs

Due to stop codon mutation.

Nonsense mutation can lead to truncated polypeptides and destroys protein functions.

A missense mutation will change the amino acid seq and alter the function of the protein usually negative but sometimes positive.

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If DNA polymerase is absent the replication will not takes place.

If helicase is absent DNA will not get separated and single strands will not form. So DNA replication will get disturbed.

primase produces small RNA strands helps in DNa replication. These small RNA stands forms complementary DNA strands.

Ligase concels DNA strands. So DNa sequence will not get completed.