[Bio3] Questions for Review on Replication/Transcription/Translation

1. What were the three models for DNA replication tested in the Meselson and Stahl experiment?
2. In the Meselson-Stahl experiment, what isotope did they use to track the mechanism of replication?
3. Describe the results they had after the first round of replication.
4. Which mechanism was discarded because of the result in the previous question?
5. What were the results of the second round of replication?
6. Why did this result eliminate the dispersive mechanism?
7. What feature of DNA is essential for self-replication?
8. Three proteins play important roles in initiating DNA replication. Name one and give its function.
9. Initiation starts in areas rich in AT sequences. Why?
10. What structure is formed when helicase starts unwinding and breaking the hydrogen bonds that hold both strands together?
11. Each replication bubble is flanked by two of these.
12. Name one difference between prokaryotes and eukaryotes during the initiation process.
13. What is the advantage of having multiple replication bubbles?
14. What happens next after initiation?
15. Why does DNA replication require a priming step?
16. Which enzyme plays a role in this stage of replication?
17. Fill in the blanks: Primases form _____ that are ____ to sequences on the original DNA strand.
18. Name two differences between the primers formed and the DNA sequence of the nontemplate strand.
19. What is the next stage of DNA replication?
20. Name the three enzymes that play a role in elongation and give their corresponding functions.
21. DNA pol III adds nucleotides to the 3′ end of primers or existing DNA strands. How?
22. Because of this property of DNA pol III, new DNA strands can only be elongated in the _____ direction.
23. For each new strand within a replication bubble, there are two types of strands formed. Give one type and its defining feature.
24. What are Okazaki fragments and how are they formed?
25. What happens after the Okazaki fragments are synthesized?
26. Which three enzymes play roles in mismatch repair and what do they do?
27. Given a template strand with the sequence: 3′ CGTCTATGAAT 5′ , what does the complementary strand look like? Make sure your answer is COMPLETE.
28. Due to the mechanism of DNA replication, we encounter problems at the 5′ ends of lagging strands called the end replication problem. What is this problem and what causes it?
29. Organisms deal with this problem in two ways. What are these two solutions?
30. What happens to cells whose telomeres are much shortened?
31. What’s the difference between transcription and translation?
32. Give one major difference between eukaryotic transcription/translation and prokaryotic transcription/translation.
33. Where does transcription occur in eukaryotes?
34. Transcription begins when…?
35. What happens during the elongation stage?
36. Why is there no need for a priming stage in transcription?
37. In transcription, the template DNA strand runs from ____ while the coding strand runs from ____.
38. The RNA transcript runs in which direction?
39. What serves as the signal for the termination of transcription in eukaryotes?
40. In eukaryotes, the RNA will be processed before it moves into the cytoplasm. Which three events take place during RNA processing?
41. Why do eukaryotes need to undergo RNA processing? (Anong importance ng 5’cap, poly A tail, at splicing?)
42. Fill in the blanks: During splicing, _____ are removed and the remaining ____ are linked to each other to form mature mRNA.
43. What catalyzes RNA splicing?
44. These are triplets of nucleotides located on the mRNA that code for specific amino acids.
45. When we say “genetic code”, what do we actually mean?
46. What happens to the mRNA when it reaches the cytoplasm?
47. After binding to the small ribosome, the first tRNA, an initiator tRNA binds. Which codon signals the binding of the first tRNA?
48. Aminoacyl-tRNA synthetase is an enzyme that is important in translation. What purpose does it serve?
49. The tRNA associated with a particular amino acid has a triplet nucleotide sequence at its base. What is this sequence called?
50. The start codon (AUG) specifies for the anticodon _____ on a tRNA which also carries the amino acid ____.
51. The codon CCC specifies for the anticodon _____ on a tRNA which also carries the amino acid ____.
52. There are 64 possible codon combinations. All of these except for three specify amino acids. What are these three codons?
53. The genetic code is NOT ambiguous, why?
54. How can GAA and GAG both code for glutamic acid? (redundancy in the genetic code)
55. What is the wobble phenomenon?
56. What is the significance/importance of wobble?
57. In transcription, after the tRNA with Met binds to the AUG sequence, what happens next?
58. After the large ribosomal subunit binds, another tRNA enters into its ___-site.
59. What happens between the amino acid carried by the tRNA in the P site and the amino acid carried by the tRNA in the A site?
60. What happens when a STOP codon reaches the A site of the ribosome?
61. Given the DNA sequence 3′ TAT AAA TAC GAG ACC CCG ACT CAC GCT 5′, what is the sequence of the mRNA transcript that will be generated using this as a template strand?
62. In which direction will this mRNA transcript run?
63. Assuming this is a prokaryotic cell, the third tRNA to attach will contain the anticodon ___ and the amino acid ___.
64. What is the polypeptide sequence generated by this mRNA?

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