MG (DNA Profiling) Flashcards

1
Q

what is DNA profiling

A
  • process where a specific DNA banding pattern, called a profile, is obtained from a person or sample of bodily tissue by using gel electrophoresis.
  • Pattern can be compared
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2
Q

What are tandem repeat sequences of DNA?

A
  • repetitive sequences of DNA introns (non-coding)
  • They all feature the same core sequence. GGGCAGGAXG (X can be any one of the 4 nucleotides).
  • Lengths are highly variable -VNTRs (variable number tandem repeats)
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3
Q

what are telomeres

A

hair pin structures on the end of chromosomes

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4
Q

DNA Profiling Procedure

A
  1. Extract DNA from sample - Can use PCR if the sample is small
  2. Digest the sample – DNA cut into small fragments with restriction endonuclease
  3. Separate the DNA fragments using electrophoresis.
  4. Banding pattern is produced.
  5. The DNA to which the individual is being compared is treated with the same restriction enzymes and is also subjected to electrophoresis
  6. Banding patterns can then be compared
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5
Q

Are the number of STRs the same in each person?

A

No. Varies from person to person.

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6
Q

How can STR (short tandem repeats) sequences be separated?

A

electrophoresis

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7
Q

Each STR is polymorphic, what does this mean

A

having more than one form – may refer to variations within the DNA sequences of a particular gene. (alleles)

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8
Q

What are the advantages of the technique used to analyse STRs

A
  • very sensitive, and even trace DNA left when someone touches an object can produce a result
  • DNA samples can be stored for many years if a crime case is unsolved
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9
Q

What are the disadvantages of the technique used to analyse STRs

A

samples have to be treated carefully to avoid contamination

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10
Q

Applications of DNA profiling in regards to forensic science

A
  • conviction of crimes
  • Proving innocence
  • Used in immigration cases to prove or disprove family relationships
  • paternity testing
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11
Q

Applications of DNA profiling in regards to maternity and paternity disputes

A
  • half of a child’s STRs are from the mum, half from dad so comparing DNA profiles of mother, father and child can establish maternity/paternity
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12
Q

Applications of DNA profiling in regards to analysis of disease

A
  • protein electrophoresis can detect type of Hb present and help in diagnosis of sickle cell anaemia
  • varying no. of repeat sequences for conditions like Huntington disease can be detected by electrophoresis
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