BIOL308 Lecture Notes - Lecture 7: Proliferating Cell Nuclear Antigen, Heterochromatin, Replication Factor C

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greyelk341

25 May 2017

School

University of Waterloo

Department

Biology

Course

BIOL308

Professor

John Heikkila

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Document Summary

1: dnap1: exonuclease that removes ribonucleotides (5 to 3), proofreads (3 to 5), fills in rna gaps with dntps. Needs a free 3"oh for polymerization and gap filling. 2: rnase h1: removes most rna made by primase except the last nucleotide (removed by 5" exonuclease dnap) 3: dna ligase: links nicked fragments by forming a po4diester bond between the 3"oh and 5"po4 (okazakis on lagging strand) 4: topoisomerase 1&2: recognize and regulate supercoiling to relax the dna for easier helicase separation at fork. Topoisomerase 2 (gyrase) needs atp and converts positive supercoils into negative ones. 5: primosome: helicase directs primase to make a primer to initiate replication. 6: replication fork: dnap3 cores are connected by tau dimers. Leading strand p3c elongated from primer in direction of fork. Lagging strand p3c (connected to leading core by tau) synthesizes okazakis from rna primer and a loop with ssbs is formed after b clamp releases okazaki from lagging p3c.

Related Questions

During DNA replication, which of the following would you expectto be true?
True or False: and why.

1. More ligase would be associated with the lagging strand thanwith the leading strand.
2. More primase would be associated with the lagging strand thanwith the leading strand.
3. More helicase would be associated with the lagging strand thanwith the leading strand.
4. DNA ligase links the 3' end of one Okazaki fragment to the 5'end of another Okazaki fragment in the lagging strand.
5. In the lagging strand, the enzyme DNA polymerase III thatproduces the next Okazaki fragment also removes the short segmentof primer RNA on the previous Okazaki fragment.

indigocrocodile46

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

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

BIOL308 Lecture Notes - Lecture 7: Proliferating Cell Nuclear Antigen, Heterochromatin, Replication Factor C

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