FINAL EXAM BIO 235
1. What evidence indicated that eukaryotic genes are not colinear with the
proteins that they encode?
Answer When DNA was hybridized to the mRNA transcribed from it, regions of DNA that not correspond to
RNA looped out.
2. What are the four major types of introns?
Answer Group I, Group II, nuclear pre-mRNA, and transfer RNA
3. Why is it that pre-mRNAs are capped but tRNAs and rRNAs are not?
Answer A protein that adds the 5' cap is associated with RNA polymerase II, which transcribes pre-mRNAs but
is absent from the RNA polymerases I and II, which transcribes rRNAs and tRNAs, respectively.
4. If a splice site were mutated so that the splicing did not take place, what would
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, be the effect on the mRNA?Answer It would be longer than normal
5. What specifies the modified sequence of nucleotides found in an edited RNA
molecule?
Answer Guide RNA
6. How are rare bases incorporated in to tRNAs?Answer Incorporated by chemical changes
one of
the standard bases
7. What types of changes take places in rRNA processing?Answer Methylation of bases,
cleavage of a larger precursor, and trimming of nucleotides from the ends of rRNAs
8. How do siRNAs and miRNAs target specific mRNAs for degradation or for the
repression of translation?Answer A siRNA or miRNA combines with proteins to form RISC, which then
pairs with mRNA through complementary pairing between bases on the siRNA and bases on the mRNA
9. CRISPR-Cas system takes place in three stagesAnswer acquisition, expression, a
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13
1. What evidence indicated that eukaryotic genes are not colinear with the
proteins that they encode?
Answer When DNA was hybridized to the mRNA transcribed from it, regions of DNA that not correspond to
RNA looped out.
2. What are the four major types of introns?
Answer Group I, Group II, nuclear pre-mRNA, and transfer RNA
3. Why is it that pre-mRNAs are capped but tRNAs and rRNAs are not?
Answer A protein that adds the 5' cap is associated with RNA polymerase II, which transcribes pre-mRNAs but
is absent from the RNA polymerases I and II, which transcribes rRNAs and tRNAs, respectively.
4. If a splice site were mutated so that the splicing did not take place, what would
1/
13
, be the effect on the mRNA?Answer It would be longer than normal
5. What specifies the modified sequence of nucleotides found in an edited RNA
molecule?
Answer Guide RNA
6. How are rare bases incorporated in to tRNAs?Answer Incorporated by chemical changes
one of
the standard bases
7. What types of changes take places in rRNA processing?Answer Methylation of bases,
cleavage of a larger precursor, and trimming of nucleotides from the ends of rRNAs
8. How do siRNAs and miRNAs target specific mRNAs for degradation or for the
repression of translation?Answer A siRNA or miRNA combines with proteins to form RISC, which then
pairs with mRNA through complementary pairing between bases on the siRNA and bases on the mRNA
9. CRISPR-Cas system takes place in three stagesAnswer acquisition, expression, a
2/
13
