GENETICS AND EVOLUTION
MOLECULAR BASIS OF INHERITANCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Excision Repair
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Cell Regeneration
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Protein Synthesis
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Strand Binding
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Detailed explanation-1: -Thus, enzymes known as DNA glycosylases remove damaged bases by literally cutting them out of the DNA strand through cleavage of the covalent bonds between the bases and the sugar-phosphate backbone. The resulting gap is then filled by a specialized repair polymerase and sealed by ligase.
Detailed explanation-2: -When Replication Errors Become Mutations. Incorrectly paired nucleotides that still remain following mismatch repair become permanent mutations after the next cell division. This is because once such mistakes are established, the cell no longer recognizes them as errors.
Detailed explanation-3: -Excision-repair pathways involve the removal or “excision” of a stretch of DNA containing damaged DNA and the resulting gap is filled in by DNA replication using the undamaged DNA as a template. In the 1960s, several groups discovered key aspects of the NER pathway in bacteria and in mammalian cells.
Detailed explanation-4: -Repair mechanisms typically correct these mistakes, but they occasionally fail to correct the error. Most of the mistakes during DNA replication are promptly corrected by DNA polymerase (the enzyme that builds new DNA during replication) by proofreading the base that has been just added (Figure 1).