d1.1 dna replication Flashcards

1
Q

3 types of replication

A
  1. full conservative replication
  2. semi conservative replication
  3. dispersive replication
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2
Q

what is dna replication used for [3]

A
  1. reproduction
  2. growth
  3. tissue replacement in multicellular organisms
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3
Q

advantages of semi conservative dna replication

A

high degree of accuracy in copying base
sequences

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4
Q

what is one monomer of dna called

A

nucleotide

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5
Q

how are strands of polypeptides arranged

A

antiparallel

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6
Q

end of pentose

A

c5 prime end
bc shape of ribose

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7
Q

what bonds link carbon tgt + which ones

A

carbon bonds
c3 + c5

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8
Q

bond between strands of polypeptide

A

h bond

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9
Q

why can the dna spiral

A

h bonds holding the antiparallel strands of polypeptides together

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10
Q

process of dna replication

A
  1. dna helicase
    - unzips the double helix
    - replication fork is formed
  2. dna polymerase
    - chases dna helicase + elongate the strands
    - new daughter strands formed
    = end up with 2 new double helixes
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11
Q

limitation of the dna polymerase

A

can only travel form 5’ to 3’ end
- dna polymerase has to leap or else a gap will form

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12
Q

name of the 2 strands during dna replication

A
  • leading strand
  • lagging strand
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13
Q

relationship of the 2 strands during dna replication

A

complementary

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14
Q

what is around when the dna replication occurs

A

free dna nucleotides

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15
Q

how to speed up the replication process in eukaryotic cells

A

multiple replication forks to speed up the replication

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16
Q

purpose of polymerase chain reaction

A

to amplify a dna sample

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17
Q

when is polymerase chain reaction needed

A

if you only have a small samples of DNA but you want to have a lot in order to use them for tests

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18
Q

real life application for polymerase chain reaction [3]

A
  1. test for viruses’ dna
  2. amplify insulin gene and insert in bacteria’s plasmids (recombination)
  3. dna fingerprinting/profiling
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19
Q

why is Tas polymerase used in polymerase chain reaction

A

heat resistant
- opt temp is 72c
- wont denature at 90c

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20
Q

why is dna helicase not needed in polymerase chain reaction

A

the double helix will just separate under heat (h bonds are very weak)

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21
Q

before polymerase chain reaction

A
  1. know the target sequence
  2. design primers that are complementary to the target sequence
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22
Q

primers definition

A

short pieces of dna that will attach on either end of the target

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23
Q

what is needed during polymerase chain reaction [4]

A
  1. many copies of the 2 primers
  2. dna polymerase
  3. nucleotides
  4. water + salt
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24
Q

purpose of dna polymerase during polymerase chain reaction

A

copies dna

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25
Q

purpose of nucleotides during polymerase chain reaction

A

act as dna building blocks

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26
Q

purpose of water + salt during polymerase chain reaction

A

to mimic the conditions inside the cell

27
Q

how is the process of polymerase chain reaction regulated

A

through repeated cycles of temperature changes

28
Q

temperature cycles of polymerase chain reaction (brief)

A
  1. 95c
    - disrupts the complementary base pairing
  2. 50c
    - complementary strands re-join
    - primers lock onto their complementary sequences before the longer strand can come back tgt
  3. 72c
    - activates dna polymerase
    - attaches at the ends of the paired primers + extends them
29
Q

95c detailed description

A
  • close to boiling- disrupts the complementary base pairing
  • 2 dna strand come apart
30
Q

50c detailed description

A
  • complementary strands re-join
  • primers are present in much greater numbers- lock onto their complementary sequences before the longer strand can come back tgt
31
Q

72c detailed description

A
  • activates dna polymerase
  • attaches at the ends of the paired primers + extends them
  • moves along the single-stranded dna, adding complementary nucleotides - goes until it falls off, reaches the end of the strand or temp change
32
Q

cycle 2 of polymerase chain reaction

A
  1. 95c
    - dna strands separate
  2. 50c
    - primers find their complementary sequences
    - bind not only to the original target dna + products from cycle 1
  3. 72c
    - polymerase extends to primers, adding complementary nucleotides as it goes
33
Q

cycle 3 of polymerase chain reaction

A
  • desired products appear
  • shorter copies of just the target sequence
34
Q

what does the primer consist of

A

a few nucleotides
(short complementary sequence of dna/rna)

35
Q

what needs to occur before a dna polymerase bind to the parent strand

A

primer bind to the parent strand first

36
Q

problem with primers

A
  • can only bind at 54c
37
Q

what does the primer sequence determine

A

where the copying starts and end

38
Q

purpose of restriction endonuclease

A

cut at the ends of the tandem repeats to create fragments of dna of different lengths

39
Q

2 types of cutting sites

A
  1. sticky end
  2. blunt end
40
Q

why is restriction enzyme used to compare dna

A

for fair comparison since the cuts occur at the same places

41
Q

advantage of gel electrophoresis

A

much faster

42
Q

process of gel electrophoresis

A
  1. use pcr to amplify dna samples collected
  2. use 1 restriction endonuclease to cut the dna specifically into fragment
  3. fluorescent marker to tag a specific dna sequence
  4. match the fluorescent bands for results
43
Q

why will the dna move during gel electrophoresis

A

dna is negatively charged. the shorter fragments will travel further than the longer fragments, as they are attracted by the positive side of the gel

44
Q

why are the dna different lengths during gel electrophoresis

A
  • short ones travel quicker
45
Q

process of dna replication

A
  1. helicase unzips and unwinds the dna
  2. the replication fork forms
  3. single strand binding porteins keep the dna from binding together again
  4. dna primase adds rna primers to the template strands
  5. dna polymerase III binds at the primers and begins to synthesise the new strands
  6. dna polymerase I removes rna primers and replaces them with dna necleotides
  7. dna ligase connects the Okazaki fragments
46
Q

function of gyrase

A

relieves the tension in the dna as it is unwound

47
Q

function of dna helicase

A

unwinds and unzips the dna by breaking hydrogen bonds between bases

48
Q

function of dna polymerase III

A

builds the new strands of DNA using the original strands as templates + proofreading function helps to prevent DNA replication errors

49
Q

function of dna primase

A

places rna primers on the template strands

50
Q

function of dna polymerase I

A

replaces rna primers with dna nucleotides

51
Q

function of dna ligase

A

connects the okazaki fragments by forming phosphodiester bonds

52
Q

function of single strand binding proteins

A

keep the two strands of dna separated and stable during replication

53
Q

what would happen if the dna polymerase I didnt do its job

A

rna primers would remain in the dna molecule

54
Q

what would happen if dna polymerase III didnt to its job

A

if mutation occurs, then it would trigger apoptosis

55
Q

how translation depends on complementary base pairing

A
  1. translation converts a sequence of mRNA nucleotides/codons to a sequence of amino acids/polypeptide/protein
  2. triplets of nucleotides/bases on «activated» tRNAs pair with complementary «triplets of» nucleotides/bases on mRNA / vice versa
  3. base pairing occurs when adenine/A pairs with uracil/U and guanine/G pairs with cytosine/C
  4. specific amino acids are attached to specific of tRNA
    e. mRNA has codons AND tRNA has anticodons
56
Q

function of Taq DNA polymerase

A
  • forms new «double-stranded» DNA by adding «complementary» bases/nucleotides
  • primers binds to targetted DNA sequences at a lower temperature
57
Q

why use Tap DNA polymerase

A

can withstand high temperatures without denaturing

58
Q

process of pcr

A
  1. denaturation (95c)
  2. annealing (54c)
  3. elongation (72c)
59
Q

sense strand nucleotides

A

same as mRNA but T instead of U

60
Q

are sense strands transcribed

A

non-transcribed

61
Q

what are the non-coding regions in DNA used as

A

telomeres and coding for production of tRNA

62
Q

which cell component synthesises actin and myosin

A

free ribosomes

63
Q

which processes do nucleosomes play a role in eukaryotes [2]

A
  1. transcription regulation
  2. dna superociling
64
Q

functions of dna

A
  1. code amino acid sequence of polypeptides
  2. regulation of gene expression
  3. introns (regulation too)
  4. telomeres (form caps at chromosome ends)
  5. coding for tRNA/rRNA
  6. allow genes to be passed to offspring