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Flashcards in DNA & Genetics Deck (32)
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1
Q

What are the applications of DNA profiling?

A
  • forensic cases: matching suspect DNA with evidence
  • paternity testing: identifying father
  • mass disasters: identifying body parts
  • missing persons investigations
  • DNA databases: cold case investigations
2
Q

DNA typing much be performed …… and ……..

A

Efficiently and reproducibly (evidence must hold up in court)

3
Q

What is the basis of DNA profiling?

A

The genome of an individual is unique (apart from twins) and is inherited from parents

4
Q

What is a genotype?

A

Genetic constitution of an individual, the total complement of inherited traits or genes of an organism

5
Q

What is an allele?

A

Alternate form of a gene at a specific locus

6
Q

What is phenotype?

A

Trait determined by genotype and environment

7
Q

What is a heterozygote?

A

Different allele

8
Q

What is a homozygote?

A

Same allele

9
Q

How much do humans differ by at a DNA level?

A

0.1 - 0.2% (3-6million base pairs)

10
Q

How many base pairs are in the human genome?

A

3.4 billion

11
Q

What are the forms of variation?

A
  1. Sequence polymorphism (single nucleotide polymorphism)
  2. Lengths polymorphism (indel)
  3. Copy number variation
  4. Chromosome inversions/genome variation
12
Q

When was the first use of DNA profiling?

A
  • 1984: Sir Alec Jeffreys
  • lead to the conviction of Colin Pitchforker for the rape and murder of two girls in 1988 and the release of another suspect
13
Q

What are the disadvantages of Southern blot?

A
  • long process

- requires lots of high quality DNA

14
Q

Southern Blot process

A
  • restriction enzyme added to DNA
  • electrophoresis to separate DNA in Aragone gel
  • transfer DNA from gel to membrane
  • probe membrane with labelled DNA of interest
15
Q

What does PCR do?

A

Increases amount of target DNA

16
Q

Mitochondrial DNA

A
  • > 1000 copies/cell
  • maternally inherited
  • not unique to individual (ie siblings with same mother)
  • target regions in forensics: highly variable region 1 (HV1) and HV2
17
Q

What variation is used in DNA profiling?

A

Short tandem repeats (STRs)

18
Q

Why are STRs used?

A
  • high level of variability wishing most populations

- have multiple alleles

19
Q

What is the PCR process?

A
  • denaturing: 95o: hydrogen bonds between DNA strands break and the double helix is separated
  • annealing: 56o: primer binds to target DNA sequences
  • extending: 72o: Taq polymerase adds complementary nucleotides to the existing single stranded DNA

Repeated for 25-30 cycles

20
Q

What is microbial forensics used for?

A

To trace outbreaks or micro-organisms (personal, bioterrorism or contamination)

21
Q

What does microbial forensics include?

A
  • using DNA and non DNA methods
  • detection of molecular variation between microbial strains
  • can infer the origin, relationships, or transmission route of a particular isolate/strain
22
Q

What are the different transmission routes?

A
  • aerosol (via droplets)
  • oral (via consumption/inhalation)
  • direct contact
  • vector Bourne (via insect)
  • zoonotic (via another animal)
23
Q

What is anthrax?

A

Disease caused by Bacillus anthracis spores

24
Q

Why are spores used in bio crime?

A
  • highly resistant
  • can be made into an aerosol using common ingredients (silica)
  • odourless and invisible
  • potential to travel many kilometres
25
Q

How does transmission in personal bio crime occur?

A
  1. Microbes transfer between humans
  2. Microbes have a genome
  3. Their genomes changes over time
  4. Genomes can be compared just like human DNA
  5. It’s not that simple though as mutation rate is so high
26
Q

How do phylogenetic trees work?

A

Points closer to each other are more genetically similar

27
Q

Category A diseases

A
  • anthrax
  • botulism
  • plague
  • smallpox
  • tularaemia
  • Ebola
28
Q

Category B diseases

A
  • meliodosis

- glanders

29
Q

Category C diseases

A
  • influenza

- SARS

30
Q

Category A biological agents

A
  • highest priority
  • easily disseminated from person to person
  • high mortality rates
  • cause public panic and social disruption
31
Q

Category B biological agents

A
  • second highest priority
  • moderately easy to disseminate
  • moderate morbidity and low mortality
32
Q

Category C biological agents

A
  • thirds highest priority
  • have the potential for mass dissemination in the future
  • have potential for high morbidity and mortality