NR 503 MIDTERM UPDATE MIDTERM EXAM QUESTIONS WITH CORRECT VERIFIED ANSWERS | 100% PASS (A+ CERTIFIED)

NR 503 MIDTERM UPDATE MIDTERM EXAM QUESTIONS WITH CORRECT VERIFIED ANSWERS | 100% PASS (A+ CERTIFIED) 1. What is the leading strand Correct Answer 5' - 3' continuous strand 2. what is the lagging strand Correct Answer 3 to 5' strand made in discontinous manner 3. what is the role of the dna polymerase Correct Answer 3' to 5' exonuclease activity that allows it to proof read 4. what are histones Correct Answer proteins that DNA wraps around 5. what do histones form Correct Answer chromatin 6. how are new nucleosomes made Correct Answer via replication fork and recombination of new and old histones 7. what are telomeres Correct Answer DNA at the tips of chromosomes 8. what happens to the length of telomeres after rounds of replication Correct Answer they shorten 9. explain the structure of telomeres Correct Answer TTAGGG repeat with the 3' end overhanging the 5' end 10. what is a telomerase Correct Answer A reverse transcriptase that includes the complementary sequence to the TTAGGG repeats and serves as a template for adding to the 3' overhang 11. what makes up a telomerase Correct Answer rna and protein 12. explain the 3' overhang in telomeres in terms of protection Correct Answer the 3' end of telomeres is bound by specific proteins that protect the ends from exonuclease attack 13. explain the steps of chromosome shortening during dna replication Correct Answer helicase unwinds the DNA strands leading strand is synthesized via dna pol lagging strand Correct Answer primase makes primer, allows dna pol to attach and fill gaps between okazaki fragments, ligase seals and the primer is then degraded leaving a gap 14. what are single stranded binding proteins Correct Answer Proteins that keep the separated strands apart and stabilize unwound DNA until the strands can be made 15. what is the primase Correct Answer makes an RNA primer so a dna pol can start replication 16. what is the sliding clamp Correct Answer ring structure that holds DNA polymerase in place during strand extension 17. are telomeres noncoding or coding Correct Answer noncoding (bc of shortening) 18. explain the steps of telomere replication Correct Answer 1. rna primer is removed exposing 5' end of lagging strand 2. telomerase binds to overhang and adds nucleotides to leading strand 3. primase, dna pol and ligase synthesize the lagging strand in the 5 to 3' direction and restore the length and primer remains 19. what is a ligase Correct Answer seals dna fragments via making new bonds 20. when the primer is removed from the telomerase, what happens Correct Answer the single stranded 5' end will fold into a t loop to protect the end of the chromosomes 21. what are primers Correct Answer oligonucleotide primers that bind to the 5 and 3' ends to be amplified 22. what are the 3 main components of pcr Correct Answer primers, pol, reaction 23. what are the 3 main steps of pcr Correct Answer denaturation, annealing, extension 24. what is a taq polymerase Correct Answer heat stable DNA polymerase (can survivee 9 mins at 97.5C) 25. what is the structure of taq polymerase Correct Answer 5 to 3' nuclease domain, inactive 3 to 5' exonuclease domain and 5 to 3' polymerase domain 26. what is the function of taq polymerase Correct Answer to add nucleotides to a DNA primer 27. explain the steps of taq pol stabilizing the transition state Correct Answer 1. 2 Mg ions in active site 2. ions bind to Asp residues 3. one metal ion activates the 3' OH on the primer for nucleophilic attack on the alpha phosphate in the dNTP 4. second metal ion stabilizes the negative charge on the leaving oxygen and allows for the by phosphates to leave 28. what are the 5 components needed for pcr reactions Correct Answer template dna, primer pair, taq pol, buffer solutions containing metal, and dNTPs 29. how many copies do you get each round of pcr Correct Answer 2 30. how many times is pcr usually repeated Correct Answer 25-40 cycles to make over 1 billion copies 31. what is the average weight of a single dna base pair Correct Answer 650 Da or g/mol 32. What is RT-PCR Correct Answer reverse transcriptase PCR that looks for mRNA expression 33. how can you screen for HIV using PCR Correct Answer take a blood sample, centrifuge the cells, take the viral rna, perform rt-pcr and then use a gel to identify if a patient has a band or not (HIV) 34. what are the temperatures at each step of pcr Correct Answer denaturation is 94C, annealing is 60C, and extension is 72C 35. What is a western blot Correct Answer Separation of proteins based on mw via electrophoresis 36. what is immunoprecipitation Correct Answer the technique of precipitating a protein antigen out of solution using an antibody that specifically binds to that particular protein 37. what is southern blotting Correct Answer Method used to obtain a particular DNA sequence from a mixture 38. what is the conservative model of dna replication Correct Answer Both parental strands stay together after DNA replication 39. what is the dispersive model of dna replication Correct Answer Parental and daughter DNA are inter- spersed in both strands following replication 40. what is the semi-conservative model of dna replication Correct Answer helix has one parental and one new dna strand 41. what is density gradient centrifugation Correct Answer separates organelles bases on their density (proteinsdnarna) 42. How did density gradient ultracentrifugation show which mechanism is uti- lized by DNA replication Correct Answer used heavy and light nitrogen isotopes, after 1 generation they found an intermediate band and after 2 generation there was one hybrid and one newly synthesized band 43. what is the direction of dna synthesis Correct Answer 5' to 3'