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BIO 301 > Course Guide Chapter 14: DNA Structure and Replication > Flashcards

Course Guide Chapter 14: DNA Structure and Replication Flashcards

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1
Q

What is the function of topoisomerase I in DNA replication?

A

relaxes the supercoiled DNA

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2
Q

What is the function of helicase in DNA replication?

A

unwinds the double helix into single stranded (ssDNA)

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3
Q

What is the function of SSB in DNA replication?

A

single-stranded DNA binding protein; stabilizes the ssDNA

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4
Q

What is the function of primase in DNA replication?

A

synthesizes RNA primers

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5
Q

What is the function of DNA polymerase I in DNA replication?

A

erases RNA primers and fills in the gaps

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6
Q

What is the function of DNA polymerase III in DNA replication?

A

DNA replication, proof reading and repair

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7
Q

What is the function of DNA ligase in DNA replication?

A

covalently joins free 3’ and 5’ ends of two DNA strands

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8
Q

What is the function of DNA gyrase in DNA replication?

A

introduces supercoiling in DNA

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9
Q

What is the first step of DNA replication?

A

supercoiling relaxed at the origin of replication by topoisomerase

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10
Q

After supercoiling relaxed at the origin of replication by topoisomerase, what is the next step of DNA replication?

A

relaxed DNA helix opened to make a replication fork by helicase

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11
Q

After relaxed DNA helix opened to make a replication fork by helicase, what is the next step of DNA replication?

A

resulting single stranded DNA is stabilized by single stranded DNA binding (SSB) proteins

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12
Q

After resulting single stranded DNA is stabilized by single stranded DNA binding (SSB) proteins, what is the next step of DNA replication?

A

primase makes an RNA primer to start the new DNA synthesis

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13
Q

After primase makes an RNA primer to start the new DNA synthesis, what is the next step of DNA replication?

A

DNA polymerase III binds to the DNA template + RNA-primer and adds nucleotides complementary to the template strand

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14
Q

After DNA polymerase III binds to the DNA template + RNA-primer and adds nucleotides complementary to the template strand, what is the next step of DNA replication?

A

new DNA synthesis occurs in the 5’ to 3’ direction on a template that runs in the 3’ to 5’ direction

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15
Q

After new DNA synthesis occurs in the 5’ to 3’ direction on a template that runs in the 3’ to 5’ direction, what is the next step of DNA replication?

A

a leading strand is synthesized continuously from 5’ to 3’ based on the template

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16
Q

After a leading strand is synthesized continuously from 5’ to 3’ based on the template, what is the next step of DNA replication?

A

DNA is synthesized in small fragments called Okazaki fragments in the lagging strand

17
Q

After DNA is synthesized in small fragments called Okazaki fragments in the lagging strand, what is the next step of DNA replication?

A

once the new strand is synthesized, DNA polymerase III proofreads it and removes errors. DNA polymerase I removes the RNA primer and completes the DNA strand

18
Q

After once the new strand is synthesized, DNA polymerase III proofreads it and removes errors. DNA polymerase I removes the RNA primer and completes the DNA strand, what is the last step of DNA replication?

A

once the small fragments are completed, DNA ligase joins the two ends of DNA strands to complete DNA replication. DNA gyrase facilitates supercoiling the DNA to compact the chromosomes into nucleosomes

19
Q

What is mismatch repair of DNA?

A

done to correct errors made during DNA replication. DNA polymerase makes approximately 1 mistake in 10,000 base pairs. Then it proofreads the newly-made DNA, removes the wrong bases and repairs the DNA to minimize the errors to 1 in a billion. These error corrections use the mismatch repair mechanism by checking complementary base pairing

20
Q

What is telomere repair or preservation of DNA?

A

occurs during DNA replication and is catalyzed by telomerase; helps prevent the telomere from getting shortened after each cell cycle. Telomerase temporarily extends the telomere region to allow the RNA primer to bind for DNA replication and once it is replicated, the extended region annealed to the RNA primer is removed to maintain the same length of telomere

21
Q

What is excision repair of DNA?

A

occurs after a cell divides and in in the G1 or G2 phase. This damage is caused by carcinogens and mutagenic radiations altering the bases or making pyrimidine dimers. Such mutations are constantly monitored by over 50 different enzymes and corrected by excising the damaged strand of DNA and making a new matching strand in its place

BIO 301 (70 decks)

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