MBIO 2020 Lecture Notes - Lecture 5: 40 Minutes, Sigma Factor, Ribosomal Rna

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grayrabbit360

10 Nov 2016

School

University of Manitoba

Department

Microbiology

Course

MBIO 2020

Professor

Dibrov Pavel

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Document Summary

5" to 3" direction towards ter site: dna pol cannot initiate synthesis without a primer, a primer is synthesized by primase (dna dependent rna pol) which makes a short, about. 10 nucleotides, complementary rna starting at ori c. After the leading strand synthesis has proceeded and the rf has moved away from ori, primase synthesizes a new primer rna which is extended by dna pol 3. Direction is towards ori c until it stops - forms a fragment okazaki fragment. As rf moves, another okazaki fragment can be formed: lagging strand is comprised of okazaki fragments, about 1000-2000 bp long, formed discontinuously. The overall replication is semi discontinuous: leading strand - continuous - 1 primer, lagging strand - discontinuous - multiple primers. Dna gyrase - moves in front of rf relieves super twisting by breaking and rejoining of one strand of dna.

Related Questions

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

1) What is the difference between the leading strand and the lagging strand in DNA replication? Place the following steps of DNA replication in right chronological order.

1. Primase adds an ribonucleotide primer
2. Initiator proteins bind the origin of replication and helicase breaks hydrogen bonds between complementary bases of double stranded template DNA
3. DNA polymerase III extends by complementary base pairing deoxyribonucleotides to the template strands
4. Ligase phosphodiester bonds the nucleotides to connect okazaki fragments nad connect fragments at the origin and where the "crotches or forks" collide
5. DNA polymerase I removes RNA primer and replaces with Deoxyribonucleotides

2) Given the template DNA and primer sequences below, what bases will be added to the primer as DNA replication proceeds? (The bases should appear in the order that they will be added)

5'-GTCGTCTCCCTTTTTAAAAACCCCCCC-3'
5'-UUUUUAAAAAGGG-3'

3) Given the DNA sequence below, what could be a primer sequence used in its replication?
5'-CGTACGGCCCCAAAATTGCTACTCTGCTG-3'

raspberryleopard304

During transcription in eukaryotes, a type of RNA polymerase called RNA polymerase II moves along the template strand of the DNA in the 3'â5' direction. However, for any given gene, either strand of the double-stranded DNA may function as the template strand. Which of the following initially determines which DNA strand is the template strand, and therefore in which direction RNA polymerase II moves along the DNA?

A. the location of specific proteins (transcription factors) that bind to the DNA

B. the specific sequence of bases along the DNA strands

C. the location along the chromosome where the double-stranded DNA unwinds

D. the position of the geneâs promoter on the chromosome

E. which of the two strands of DNA carries the RNA primer

MBIO 2020 Lecture Notes - Lecture 5: 40 Minutes, Sigma Factor, Ribosomal Rna

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