BIO130H1 Lecture Notes - Lecture 7: Helicase, Primase, Dna Replication

81 views2 pages

tanelephant390

2 Feb 2017

School

Department

Course

Professor

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

ash-mr18 and 40043 others unlocked

BIO130H1 Full Course Notes

Verified Note

31 documents

Document Summary

Bio130 lecture 7: dna helicase unwinds the dna; the initiator proteins help the helicase to bind to the origin. This requires atp for energy: the primase binds to the helicase; it is now called a primosome, the rest of the replication machinery binds. The dna helicase is always on the lagging strand, which acts as the strand: the helicase has 6 subunits, the helicase therefore is a quaternary structure. The nucleotides can only be added on a 3" end: single strand binding proteins keep dna strands separated. Ssdna binds and prevents the strands from forming hydrogen bonds: rna primers are synthesized by primase which activate the activity of the dna polymerase. Primase makes the rna primer in a 3" to 5" direction along the template strand (denovo) The leading strand is replicated continuously from one rna primer, while the lagging strand is made discontinuously from multiple rna primers: sliding clamps, hold polymerase onto 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

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

plumsardine151

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

BIO130H1 Lecture Notes - Lecture 7: Helicase, Primase, Dna Replication

BIO130H1 Full Course Notes

Document Summary

Get access

Related textbook solutions

Molecular Cell Biology

Biology: Science for Life with Physiology

Concepts of Biology

Biology

Essentials of Biology

Related Documents

BIO130H1 Study Guide - Quiz Guide: Tata Box, Stem-Loop, Okazaki Fragments

BIO130H1 Chapter Notes - Chapter 4: Okazaki Fragments, Sigma Factor, Helicase

BIO130H1 Study Guide - Midterm Guide: Post-Translational Modification, Exon, Spliceosome

Related Questions