BISC 202 Lecture Notes - Lecture 24: Dna Replication, Helicase, Transfer Rna

64 views8 pages

coffeegrasshopper724

7 Dec 2018

School

Simon Fraser University

Department

Biological Sciences

Course

BISC 202

Professor

Michael Hart

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Topoisomerase moves in advance of helicase to relive strain on the dna double strand: helicase unwinds the double strand of dna, forming a replication fork. Single stranded binding proteins bind to the dna strands to prevent re-attaching. Rna primase synthesizes a primer on the 3"end of each template strand to provide an initiation point for dna polymerase iii: dna polymerase iii starts adding nucleotides to the template strand according to the complementary base-pairing rule. Dna pol iii moves in the 3" to 5" direction, it moves toward the replication fork on the leading strand and away from the fork on the lagging strand. New dna strand is being formed in the 5" to 3" direction. Rna primase synthesizes more rna primers on the lagging strand. However, the hairpin loop structure is in its way, rna pol has no option but stops transcribing. No post-transcriptional modi cations, transcription and translation happen at the same time in prokaryotes.

Related Questions

Order the following steps of the DNA replication process fromfirst to last. (From 1 to 8)

DNA ligase joins Okazaki fragmments together

Elongation of leading strands occurs continuosly and elongationof lagging strands occurs via generation of Okazaki fragments. Bothare synthesized in 5' to 3' direction.

DNA polymerase I removes the RNA primers and replaces them withDNA nucleotides

DNA polymerase III starts adding DNA nucleotides to the 3' endof the existing RNA chain.

Helicase untwists the double helix at the replication fork

Single-stranded binding proteins bind the unpaired DNA strands,keeping them from re-pairing.

Topoisomerase helps releive the strain caused by DNA untwisting.It breaks, swivels and rejoins DNA strands.

Primase starts a complementary RNA chain using parental DNAstrand as a template

lilacgoose192

Multiple choice questions:

1) For DNA Polymerase III to work, which of these components has to act first? (A. Conservative replication, B. Newly replicated strand, C.Primase, D. RNA, E.Mutation rate)

2) The double helix of DNA is wrapped about 1 3/4 times around which of these components? (A. Helicase, B. DNA polymerase III, C. DNA polymerase I, D.Nucleosome, E. DNA ligase)

3) Which strand is produced more rapidly? (A.Okazaki fragment, B. Lagging strand, C. Leading strand, D. 3' , E. 5' )

4) During DNA replication in the lagging strand there is production of this component? (A. Okazaki fragment, B. mRNA, C. tRNA, D. proteins, E. none of the above)

5) Which enzyme is used first to permit DNA polymerase III to begin replicating the 3' stand? (A. Conservative replication, B. Parental stand, C. Primase, D. RNA, E. Mutation rate)

6) Which enzyme unwraps the double helix? (A. Helicase, B. DNA polymerase III, C.DNA polymerase I, D. Nuclesome, E. DNA ligase)

Thanks for any feedback, want to verify my answers.

1. During DNA replication, proteins unwind the DNA duplex, and separate the DNA strands. Those proteins include:

a.) DNA polymerase and ligase

b.) Single-stranded DNA binding and protein primase

c.) Helicase and DNA polymerase

d.) Helicase and single-stranded DNA binding protein

2. What determines the nucleotide sequence of the newly synthesized strand during DNA replication?

a.) The particular DNA polymerase catalyzing the reaction

b.) The relative amounts of the four nucleotide triphosphates (ATP, GTP, CTP, and TTP) in the cell

c.) The nucleotide sequence of the template strand

d.) The primase used in the reaction

e.) Both A and D

3. The leading and the lagging strands differ in that

a.) The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.

b.) The leading strand is synthesized by adding nucleotides to the 3â hydroxyl (OH) end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5â phosphate (PO4) end.

c.) The leading strand is synthesized continuously, whereas the lagging strand is synthesized in short fragments that are ultimately stitched together.

d.) Both A and B

e.) Both A and C

BISC 202 Lecture Notes - Lecture 24: Dna Replication, Helicase, Transfer Rna

Document Summary

Get access

Related Documents

BISC 202 Study Guide - Final Guide: Academic Dishonesty, Purine, Dna Ligase

BISC 202 Lecture Notes - Lecture 23: Telomerase, Telomere, Dna Replication

BISC 202 Lecture Notes - Lecture 3: Complementary Dna, Primase, Helicase

Related Questions