Biochemistry 2280A Lecture Notes - Lecture 15: Atp Hydrolysis, Romanian Top 100, Exonuclease

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carminewalrus808

22 Jan 2018

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Replication starts at the replication origin (rich in at pairs) Bacteria only has one replication origin but more complicated organisms have more. Initiator proteins help to open the double helix. Helicase then binds at the forks and continues to unwind the dna consuming atp as it does so (replication bubble) Ss-binding proteins prevent the dna from winding back together or from making a secondary structure with itself: priming. Primase synthesizes a small primer (10-20 nucleotides) composed of rna. This is (cid:374)e(cid:272)essar(cid:455) (cid:271)e(cid:272)ause dna pol(cid:455)(cid:373)erase (cid:272)a(cid:374)"t s(cid:455)(cid:374)thesize dna (cid:449)ithout a pri(cid:373)er: dna synthesis. Sliding clamp binds to dna polymerase to keep it on the template. Leading strand is synthesized towards the replication fork (continuous synthesis) Dna fragments from the lagging strand must be joined together. Dna polymerase iii dissociated and dna polymerase i binds. Dna polymerase i degrades the pri(cid:373)er (cid:894)5" 3" e(cid:454)o(cid:374)u(cid:272)lease(cid:895) a(cid:374)d s(cid:455)(cid:374)thesizes repla(cid:272)e(cid:373)e(cid:374)t dna (cid:894)the (cid:862)(cid:374)i(cid:272)k(cid:863) is (cid:373)o(cid:448)ed arou(cid:374)d(cid:895) The (cid:862)(cid:374)i(cid:272)k(cid:863) is sealed (cid:271)(cid:455) dna ligase.

Related Questions

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

1.When a protein binds to DNA at a site defined by a particular nucleotide sequence, with which parts of the DNA does the protein primarily interact?

A. the phosphate and deoxyribose groups in the DNA backbone

B. the phosphate and deoxyribose groups in the DNA backbone, and hydrophobic interactions with the nucleotide bases

C. nucleotide bases within the major grooves of the DNA

D. nucleotide bases within the major and minor grooves of the DNA

E. none of the above

2. Which of the following proteins binds to DNA with sequence specificity?

A. POI Ill holoenzyme

B. DnaA

C. DnaB

D. Dam methylase

E. Both B and D

3. Which of the following is NOT a functional parallel among all known cellular systems of DNA replication?

A. Replication is initiated at specific sites

B. Replication is continuous on the leading strand and discontinuous on the lagging strand

C. DNA replication is semiconservative

D. Replication forks move away from the origin in one direction

E. Nucleases, polymerases and ligases replace RNA primers with DNA and seal the remaining nick

4. A DNA polymerase cannot synthesize a DNA strand de novo (from the beginning) from a mixture of dNTPs. Which of the following explains the role of the primer in the reaction promoted by this enzyme?

A. The primer is an initiation protein with attached nucleotides that binds to the template and to which new nucleotides are added to the 3 ' end.

B. The primer is an initiation protein with attached nucleotides that binds to the template and to which new nucleotides are added to the 5' end.

C. The primer is a preexisting strand of RNA or DNA to which new nucleotides are added to the 3' end.

D. The primer is a preexisting strand of RNA or DNA to which new nucleotides are added to the 5' end.

E. The primer is a preexisting strand of DNA synthesized by DNA pol I, prior to replicative DNA synthesis by DNA pol Ill.

5. Universal features of DNA polymerases include:

A. 5'-3' exonuclease function.

B. Formation of an 'closed' conformation of the polymerase when the template-nucleotide base pair is correct.

C. Use of a single magnesium ion to orient reacting molecules and assist in dissipation of the negative charge that develops during nucleotidyl transfer.

D. Alignment of conserved residues in the active site for attack of the DNA primer by the 3 'OH on the incoming nucleotide.

E. Continuous unbinding and rebinding of the polymerase to the DNA template as each nucleotide is added.

byzantiumscorpion425

Biochemistry 2280A Lecture Notes - Lecture 15: Atp Hydrolysis, Romanian Top 100, Exonuclease

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