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Bio Topic 6 - Infections, Immunity & Forensics > 6.1 - Forensic biology > Flashcards

6.1 - Forensic biology Flashcards

(39 cards)

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1
Q

What are the 3 main ways of identifying a body?

A
  1. fingerprints
  2. dental records
  3. DNA profiling
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2
Q

What are the 4 main ways of determining time of death?

A
  1. body temperature
  2. rigor mortis
  3. decomposition
  4. forensic entomology
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3
Q

What are the 2 methods of measuring core body temperature?

A
  1. via the rectum
    (if present) 2. via an abdominal stab
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4
Q

Which 6 factors affect the cooling of a body?

A
  1. body size
  2. body position
  3. clothing
  4. air movement
  5. humidity
  6. temperature of surroundings
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5
Q

What type of curve does the cooling of a body follow?

A

sigmoid curve

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6
Q

What is the time period, post mortem, that means that a temperature of a body is useful for estimating time of death?

A

24 hours

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7
Q

Why will a body cool more rapidly if it is immersed in water?

A

water is a better conductor of heat than air

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8
Q

What is rigor mortis?

A

the process of muscles stiffening after death

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9
Q

What is the process of ‘rigor mortis’?

A
  1. after death, oxygen-dependent reactions stop
  2. anaerobic respiration starts & produces lactic acid
  3. pH of the cells falls, inhibiting enzymes & anaerobic respiration stops
  4. the ATP needed for muscle contraction is no longer produced. 5. bonds between the muscle proteins become fixed
  5. proteins can no longer move over one another to shorten the muscle, fixing the muscle and joints
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10
Q

What are the 10 main stages of decomposition?

A
  1. greenish discolouration of abdomen
  2. discolouration spreads across the body
  3. green turns to reddish-green, then purple-black
  4. gas/lqiuid blisters appear on the skin
  5. gases form in the guts because of bacteria action bloating the body
  6. further decomposition releases the gases
  7. fluids produced by decay drain away
  8. soft tissues shrink as a result
  9. decay slows as there is no moisture
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11
Q

How can forensic entomology be used to estimate time since death?

A

the species that is present on the corpse & the stage of their life cycle that they are in can help to estimate time of death

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12
Q

What is succession?

A

the process of organisms on the body changing over time

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13
Q

What are the stages of succession?

A
  1. bacteria
  2. fly larvae
  3. beetles
  4. body has been fully decomposed
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14
Q

What are the 3 factors which affect the species present during the stages of succession?

A
  1. weather conditions
  2. size of body
  3. location of body
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15
Q

What are the sequences of DNA that code for amino acids called?

A

exons

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16
Q

What are the sequences of DNA that do not code for amino acids called?

17
Q

What happens to the introns when mRNA is produced?

Study These Flashcards
A

introns are spliced out

18
Q

Are introns and exons inherited together?

19
Q

What are introns made up of?

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A

consist of repeating DNA sequences, known as STRs (short tandem repeats) or satellites

20
Q

What happens to the encoded polypeptide if a mutation occurs in an intron? Why?

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A

there is no effect - as introns are non-coding

21
Q

How many base pairs can STRs have?

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A

2-50 base pairs

22
Q

If you have two of the same STR, where are they found?

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A

the same STRs occur at the same locus on both chromosomes in a homologous pair

23
Q

When the same STRs are found at the same locus on both chromosomes, what is their only difference?

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A

the STRs can repeated a different number of time on each chromosome

24
Q

What is the difference between the same STRs in different individuals?

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A

the no. of repeats at each locus is different

25
How many different introns need to compared in order for a criminal to be convicted?
13
26
Why do we use STRs to convict criminals?
each person has a large number of introns with lots of STR loci, so there is a large variation in the no. of repeats at each locus - this means that 2 individuals are highly unlikely to have the same combination of STRs
27
What are the 4 reasons why we use introns and not exons (genes)?
- non-coding sequences - not subject to selection pressures - many random muations occur - unique, whereas gene sequences are often shared
28
What are 4 sources of DNA for genetic profiling?
1. saliva 2. blood 3. teeth 4. bones
29
What is DNA profiling used for?
to determine the genetic relationships between different organisms
30
How do you produced a DNA fragment?
- use restriction endonucleases (restriction enzymes) found in bacteria to cut DNA into fragments - these enzymes are very specific & cut DNA where they find a specific sequence of bases (4-6 bases long)
31
What are the 5 steps of making a DNA profile?
1. obtain an appropriately sized sample & extract the DNA 2. Make different length fragments by cutting up the DNA 3. Amplify DNA using PCR 4. Separated & visualised fragments 5. compare fragments with a reference point
32
What is needed in order to apply the results a DNA profile?
a comparison with a DNA sample of the suspect, a relative or an item
33
What happens if the comparison DNA sample is really small?
PCR is used to amplify garment of DNA
34
What is the function of PCR?
amplify and increase the amount of DNA to be analysed
35
What is PCR?
artificial replication of DNA
36
Wha are the 4 things required for PCR to take place?
1. DNA is made of 2 antiparallel strands 2. each strand has a 3' and 5' end 3. DNA grows only from 3' end 4. complementary base pairing
37
How is PCR different from DNA replication?
- only replicates short sequences of base pairs rather than entire chromosomes - requires primers to begin process - a series of specific temperatures are needed
38
What is the process of PCR? (temperatures, enzymes etc.)
1. DNA sample mixed with DNA nucleotide & DNA polymerase 2. mixture heated 95℃. this breaks hydrogen bonds holding DNA strands together 3. primers added & attach to each 3' end of strand 4. temperatures reduced to 55℃ which allows primers to bind at end of samples 5. mixture heated to 72℃ for DNA polymerase to attach nucleotides 6. repeated cycles of heating & cooling amplify this region by thermal cycle (30 mins
39
Describe the role of decomposers, such as microorganisms, in the carbon cycle.
decomposers respire and break down organic material. this releases carbon dioxide into the atmosphere

Bio Topic 6 - Infections, Immunity & Forensics (4 decks)

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