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Biology - Molecular Genetics > DNA Replication > Flashcards

DNA Replication Flashcards

1
Q

Meselson and Stahl big idea

A

DNA undergoes semiconservative replication

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2
Q

What does semiconservative replication mean?

A

DNA opens gets copied and a new strand bonds with an old strand

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3
Q

Step 1 of DNA Replication

A

DNA must unwind to expose a single stranded template

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4
Q

What enzymes do step 1 of DNA replication use?

A
  • Helicase
  • Topoisomerases (Gyrase)
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5
Q

What does helicase do?

A
  • Unzips and unwinds the double helix
  • Breaks hydrogen bonds
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6
Q

What does topoisomerase (gyrase) do?

A
  • Detangler
  • Prevents supercoils by nicking and resealing DNA
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7
Q

Step 2 of DNA Replication

A

DNA must be held open, not to reform a coil

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8
Q

What do Single Stranded Binding Proteins do?

A
  • Bind to the uncoiled DNA and keep it open
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9
Q

Step 3 of DNA Replication

A

A primer must be created before DNA synthesis can occur

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10
Q

What is primer?

A
  • Short sequence of RNA, complementary to template
  • 3’ end where DNA synthesis can begin
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11
Q

What is primase?

A

Enzyme that synthesizes RNA primer

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12
Q

What is RNA polymerase?

A

Synthesizes primers on leading strand

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13
Q

Note about primase

A

Primase is a type of RNA polymerase

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14
Q

Leading strand

A
  • New strand that is synthesized continuously
  • Synthesized towards replication fork
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15
Q

Lagging Strand

A
  • Synthesized in short fragments called Okazaki fragments which are later joined together
  • Discontinuously
  • Synthesized away from replication fork
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16
Q

Step 4 of DNA Replication

A

DNA synthesis begins

17
Q

What is DNA polymerase 3

A
  • Enzyme that catalyzes the addition of nucleotides complementary to the template strand
18
Q

What is a nucleoside triphosphate

A
  • Free floating nucleotides with extra phosphate for energy
  • Each nucleotide that is added to a growing DNA strand is a nucleoside triphosphate
19
Q

What does the phosphate in a nucleoside triphosphate do?

A
  • The phosphate provides energy needed to drive the reaction that makes phosphodiester bonds
20
Q

What direction does DNA synthesis occur in?

A

5’ to 3’ direction

21
Q

DNA polymerase 1, first function

A
  • Edits mistakes
  • Proofreads chain
  • Exonuclease activity
22
Q

Step 5 of DNA Replication

A

Synthesis of DNA occurs on both template strands

23
Q

Step 6 of DNA Replication

A

RNA primers are removed

24
Q

DNA polymerase 1, second function

A
  • chews up RNA primers and replaces them with DNA nucleotides
  • All primers are removed
25
Q

What is Nick Translation?

A

When primers are replaced by DNA nucleotides

26
Q

Step 7 of DNA Replication

A

All nicks are repaired

27
Q

What is DNA Ligase

A
  • Acts like glue to make phosphodiester linkages
  • Seals the nicks between Okazaki fragments

Biology - Molecular Genetics (12 decks)

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