Heres the link to the article. http://www.nature.com/scitable/topicpage/dna-repl
ID: 222920 • Letter: H
Question
Heres the link to the article.
http://www.nature.com/scitable/topicpage/dna-replication-and-causes-of-mutation-409
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. Mutation to passed from one generation to another, it must be germ line (sperm or egg cells). This mutation occur once in parents and infect all the cells, which later on get transferred to their generation. On the other hand, somatic mutation does not transferred to next generation.
2. The major cause of DNA replication error arises during proofreading or inability to repair the error by mutation during process of replication. Various events in replication results in deletion, insertion and mismatching of base pairs resulting in harmful effect. This reults in activation of repair system such as mismatch repair, base excision, nucleotide repairs etc.
3. Somatic cells are continousy replaced in the body in cell cycle, thus chance of mutation is very less. But if mutation occurs in somatic cells results in cancer, only when genes involved in cell cycle gets mutated. this results in daughter cell is mutated, resulting in the cancer progression.
4. Different repair mechanism are base excision, nucleotide, mismatch repair with help of different enzymes availble in different process. The proofreading plays an important process, but if it gets hampered results in some dreadful diseses. In eukaryotic speed and accuracy always goes side by side. If mutation occurs, and machinery recognize and need more time to repair speed compromises, otherwise accuracy. This problem is main problem so that it does not eliminate all error and synthesize error sequence to keep machinery moves on.