Read the following article, DNA Replication and Causes of Mutation ( http://www.
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Question
Read the following article, DNA Replication and Causes of Mutation ( http://www.nature.com/scitable/topicpage/dna-replication-and-causes-of-mutation-409 ) , and answer the following questions.
1. For a mutation to be passed down from one generation to the next, in what cell lineage must the mutation occur?
2. What are the major causes of DNA replication errors? Provide a specific example.
3. How can a mutation in a somatic cell lead to cancer? (hint: review Chapter 12)
4. Why may have DNA repair mechanisms in eukaryotes not evolved to completely eliminate all mutations from our genome?
Explanation / Answer
1. For a mutation to be passed down from one generation to the next, in what cell lineage must the mutation occur?
Answer:
Mutations occurring in gamete cells will be passed on to the subsequent generations.
2. What are the major causes of DNA replication errors? Provide a specific example.
Major causes of DNA replication errors are caused by mis-pairings of basepairs
Example: A with a G instead of a T
3. How can a mutation in a somatic cell lead to cancer? (hint: review Chapter 12)
Mutations in genes that code for cell cycle regulation would result in cancer in somatic cells
Example: mutated HRAS gene was associated with bladder cancer. HRAS encodes for a protein that helps regulate cell division.
4. Why may have DNA repair mechanisms in eukaryotes not evolved to completely eliminate all mutations from our genome?
Not all mutations are bad, in fact mutations are a great source of genetic variation and raw material for evolution. Absence of mutations due to perfect DNA mechanisms means no genetic variation
Successful organisms have thus evolved the means to repair their DNA efficiently but not too efficiently, leaving just enough genetic variability for evolution to continue.
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