21.5 genetic fingerprinting Flashcards

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1
Q

what are VNTRs?

A

variable number tandem repeats (non-coding dna bases)

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2
Q

why are VNTRs used in genetic fingerprinting?

A

number and length of VNTRs are different between individuals & give a unique pattern
- closer relatives would have similar VNTRs pattern

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3
Q

what are the 5 steps of genetic fingerprinting?

A

1) extraction
2) digestion
3) separation
4) hybridisation
5) development

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4
Q

how is dna extracted and amplified in genetic fingerprinting?

A

dna is extracted from tissue of interest (eg. swab, syringe) & amplified by PCR

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5
Q

what is used in digestion of genetic fingerprinting & how is it carried out?

A

restriction endonuclease cut dna into fragments
- recognition sites (in palindromes) will be different due to different VNTRs -> different dna fragments are made

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6
Q

how is gel electrophoresis carried out? (3)

A
  • dna placed in well of gel & is attracted to positive voltage (since phosphate groups of dna is negative)
  • gel offers resistance to dna fragments & smaller fragments travel furthest
  • radioactively labelled dna is used to bind to VNTRs & gel is exposed to x-ray film
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7
Q

how is separation of dna carried out after gel electrophoresis?

A

gel is immersed in alkaline solution to change double-stranded DNA -> single stranded DNA fragments
- single stranded DNA is transferred from gel to nylon membrane by southern blotting

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8
Q

how is hybridisation carried out in dna separation?

A

radioactively dna probes are added to single-stranded dna fragments on nylon membrane
- probes are complementary to VNTRs and bind under specific conditions of temperature & pH

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9
Q

how are hybridised dna fragments developed?

A

x-ray film is put over nylon membrane & radiation exposes the film and shows dark lines
- unique dna pattern for each individual
- results are interpreted & developed -> probability of dna being from same individual is calculated

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10
Q

what are the 4 uses of dna fingerprinting?

A

1) determine genetic variation & relationships
2) forensic science (crime scenes)
3) medical diagnosis
4) plant & animal breeding

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11
Q

how is dna fingerprinting used in diagnosing huntington’s disease?

A

determine number of AGC base sequence repeated:
<30 unlikely
>38 almost certain
>50 early onset

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12
Q

how is dna fingerprinting used in plant & animal breeding? (3)

A

prevent undesirable breeding on farms & zoos
determine paternity for pedigree
identify organism with certain beneficial allele of a gene for breeding purposes

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