Structure and Replication of DNA Flashcards

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1
Q

What is DNA

A

Polymer of 4 different nucleotides, arranged in a repeating fashion

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2
Q

Each nucleotide consists of

A

alternating deoxyribose sugar and phosphate sections with one of 4 bases attached to sugar

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3
Q

amino acid

A

sequence of 3 bases, amino acids are assembled to produce a particular protein

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4
Q

Structure of DNA

A

Anti-parallel double-stranded helix held together by complementary base pairs

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5
Q

Sugar phosphate back bone structure

A

5’ end at phosphate

3’ end at deoxyribose end

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6
Q

5’ end

A

phosphate

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7
Q

3’ end

A

deoxyribose

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8
Q

what does DNA store

A

Genetic information

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9
Q

Base sequence forms

A

Genetic code

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10
Q

Genotype is determined by

A

Sequence of bases

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11
Q

Need for DNA replication

A

Make identical copy

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12
Q

Requirements for DNA replication

A

Original DNA template

Free nucleotides

DNA polymerase

Primers

Ligase

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13
Q

DNA polymerase

A

Enzyme that adds new nucleotides to growing strand of DNA

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14
Q

Primers

A

Short sequence of nucleotides that bind to 3’ end of template DNA allowing DNA polymerase to add free DINA nucleotides

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15
Q

Stage 1 DNA replication

A

DNA unwound and unzipped

-helix unwounded
-special molecules break weak hydrogen bonds between bases
- process occurs at several locations on a DNA molecule

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16
Q

Stage 2 of DNA replication

A

DNA polymerase adds free DNA nucleotides to 3 end of primer

17
Q

Leading strand

A

synthesised continuously DNA polymerase adds to 3’ ended strand

happens in 5’ to 3’ direction

18
Q

Lagging Strand

A

synthesised in fragments

nucleotides cannot be added to 5’ end because DNA polymerase can only add in a 5’ to 3’ direction.

fragments sealed together by enzyme ligase

19
Q

Stage 3 DNA replication

A

new strand twists to form double helix - each identical to original

20
Q

Polymerase Chain reaction

A

Technique used for amplification of DNA in vitro

easy and cheap

21
Q

PCR and DNA

A

PCR amplifies DNA using complementary primers for specific target DNA sequence

22
Q

What is PCR used for

A

DNA for criminal investigations

Settle paternity suits

Diagnose genetic disorders

23
Q

Requirements for PCR

A

DNA

Complementary primers

Thermal cycler

Heat tolerant polymerase

Supply of nucleotides

24
Q

PCR process

A
  1. Heated 92-98 degrees to denature and separate strands
  2. cooled to 50-65 degrees to allow primers to bind to target DNA
  3. Complementary primers added
  4. Heated 70-80 degrees - heat tolerant DNA polymerase added
  5. Repeated cycles of heating and cooling amplify target region of DNA
25
Q

Thermal cycler allows process to be

A

automated

continually denatured and replicated