BSC-2010 Lecture Notes - Lecture 3: Dna Polymerase I, Okazaki Fragments, Dna Ligase

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5 Nov 2016

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You (cid:272)a(cid:374) o(cid:374)l(cid:455) (cid:271)uild o(cid:374) a 3(cid:859) stra(cid:374)d o(cid:374) dna. (cid:455)(cid:374)thesis of leadi(cid:374)g stra(cid:374)ds is (cid:272)o(cid:374)ti(cid:374)uous i(cid:374) 5(cid:859) to 3(cid:859) e(cid:374)d. The lagging strand elongates the other strand. Dna polymerase must work in the direction away from the replication fork. The lagging strand is synthesized by dna polymerase iii as a series of segments called okazaki fragments. The leading strand is synthesized towards the replication fork; the lagging strand is synthesized away from the replication fork. Dna polymerase i can remove rna nucleotides and fill in the gap with dna nucleotides. Fills in the gaps with dna nucleotides. Ends of okazaki fragments must be joined together. Dna ligase can join the 5(cid:859) e(cid:374)d of o(cid:374)e dna (cid:373)ole(cid:272)ule (cid:449)ith the 3(cid:859) e(cid:374)d of a(cid:374)other. Eukaryote cells do not have termination sequences. Every time you copy a chromosome, telomeres get shorter. Eukaryotic chromosomal dna molecules have repetitive, non-coding nucleotide sequences at their ends called telomeres.

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

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

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

BSC-2010 Lecture Notes - Lecture 3: Dna Polymerase I, Okazaki Fragments, Dna Ligase

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