DNA polymerase occasionally incorporates the wrong nucleotide during DNA replication. If left unrepaired, the base-pair mismatch that results will lead to mutation in the next replication. As part of a template strand, the incorporated wrong base will direct the incorporation of a base complementary to itself, so the bases on both strands of the DNA at that position will now be different from what they were before the mismatch event. The MER-minus strain of yeast does not have a functional mismatch excision repair system, but it has normal base excision repair and nucleotide excision repair systems. Which of the following statements is correct about differences in the mutation spectrum between MER-minus and wildtype yeast? More than one answer is correct. Options: More point mutations will arise in MER-minus yeast. Fewer point mutations will arise in MER-minus yeast as compared with wildtype. Of the total point mutations that do occur, the fraction in which G is replaced by C will be lower in MER-minus yeast than in wildtype. (Hint: imagine the very first mismatch event and ask yourself if base excision repair could handle it.) Of the total point mutations that do occur, the fraction of in which G is replaced by A will be lower in MER-minus yeast than in wildtype. Of the total point mutations that do occur, the fraction in which A is replaced by G will be lower in MER-minus yeast.
Gene Interactions
When the expression of a single trait is influenced by two or more different non-allelic genes, it is termed as genetic interaction. According to Mendel's law of inheritance, each gene functions in its own way and does not depend on the function of another gene, i.e., a single gene controls each of seven characteristics considered, but the complex contribution of many different genes determine many traits of an organism.
Gene Expression
Gene expression is a process by which the instructions present in deoxyribonucleic acid (DNA) are converted into useful molecules such as proteins, and functional messenger ribonucleic (mRNA) molecules in the case of non-protein-coding genes.
DNA polymerase occasionally incorporates the wrong
The MER-minus strain of yeast does not have a functional mismatch excision repair system, but it has normal base excision repair and nucleotide excision repair systems.
Which of the following statements is correct about differences in the mutation spectrum between MER-minus and wildtype yeast?
More than one answer is correct.
Options:
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More point mutations will arise in MER-minus yeast. |
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Fewer point mutations will arise in MER-minus yeast as compared with wildtype. |
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Of the total point mutations that do occur, the fraction in which G is replaced by C will be lower in MER-minus yeast than in wildtype. (Hint: imagine the very first mismatch event and ask yourself if base excision repair could handle it.) |
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Of the total point mutations that do occur, the fraction of in which G is replaced by A will be lower in MER-minus yeast than in wildtype. |
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Of the total point mutations that do occur, the fraction in which A is replaced by G will be lower in MER-minus yeast. |
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