DNA replication and manipulation Flashcards

1
Q

Where does DNA replication occur

A

S phase

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2
Q

What shape is DNA in

A

helix w two antiparallel strands

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3
Q

Why do hydrogen bonding inbetween DNA strands allow it to unravel

A

bc they are weaker

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4
Q

What direction is DNA made

A

5’-3’ only

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5
Q

DNA replication conservative model

A

no mixing DNA

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6
Q

Semiconservative model

A

evenly split mixed DNA

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7
Q

Dispersive model

A

random mixing DNA

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8
Q

Which experiment showed that DNA replication is semi-conservative

A

messelsohn and stahl

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9
Q

How did messelsohn and stahl do their experiment

A

growing bacteria in lighter and lighter nitrogens and DNA forms bands when centrifuged

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10
Q

Draw out semiconservative model

A

Dark strand on first, split half on second, and light and half on third

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11
Q

If DNA replication was conservative which bands would be observed after one round of replication

A

heavy and light

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12
Q

Complications in DNA replication(4)

A
  1. unwinding tension
  2. only add nucleotides to existing nucleotide
  3. opposite directions on each strand
  4. pieces need to be joined together
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13
Q

Helicase

A

unwinds double helix at replication forks

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14
Q

Single-strand binding protein

A

binds and stabilizes single stranded DNA when it is used as a template

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15
Q

topoisomerase

A

relieves strain of overwinding by breaking, swiveling, and rejoining DNA strands

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16
Q

primase

A

makes RNA primer at 5’ of leading and 5’ of each okazaki fragment of laggiing

17
Q

DNA pol III

A

uses parental DNA as template and makes new DNA by adding nucleotides to RNA primer

18
Q

DNA pol I

A

removes RNA primers and replaces with DNA nucleotides

19
Q

DNA ligase

A

joins okazaki fragments on lagging strand
leading strand: joins 3’ to rest of leading

20
Q

Step 1 of replication (3)

A
  1. helicase unwinds
  2. topoisomerase relieves stress
  3. single-stranded binding proteins stabilize single strands
21
Q

Step 2 of replication

A
  1. RNA primer attaches to 5’ primer
  2. elongation as bases are added
  3. RNA primers are replaced with DNA
  4. pieces in the lagging strand and put together
22
Q

Prokaryote replication

A

single origin and moves around the circular c chromosome in both directions

23
Q

Difference between eukaryotic and prokaryotic replication

A

prokaryotic one origin
eukaryotic many origins of replication

24
Q

Telomeres

A

protect ends of chromosomes

25
Q

Relation between age and telomere length

A

As age increases, telomere length decreases

26
Q

End replication problem

A

few bases at ‘5 end of new strands are missing

27
Q

Telomerase

A

some cells express this
carries its own RNA template

28
Q

Some types of cancer cells express telomerase to

A

divide a greater number of times before dying

29
Q

Polymerase Chain Reaction purpose

A

make many copies of a DNA fragment in vitro

30
Q

Primers

A

oglionucleotides

31
Q

Things you need in a PCR(5)

A
  1. DNA template
  2. Primers
  3. DNA polymerase
  4. dNTPs
  5. Buffer/cofactors
32
Q

Restriction enzymes

A

recognize and cut specific sequences of DNA

33
Q

EcoRI restriction endonuclease

A

restriction enzyme

34
Q

restriction enzymes with plasmids

A

used to insert genes/DNA fragments of interest into a vector

35
Q

agarose gel electrophoresis

A

used to visualize DNA

36
Q

shorter strands

A

migrates faster

37
Q

larger strands

A

migrate slower

38
Q

larger strands

A

migrate slower

39
Q

CRISPR

A

used to insert and change gene sequences