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FORENSICS
Investigating time of death:
As soon as a person dies, chemical changes occur in order, so can be used to
estimate the time of death.

Rigor mortis/degree of muscle contraction:
Begins when muscle cells become deprived of oxygen
Respiration is anaerobic, causing the build up of lactic acid in…

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Few days-weeks ­ microorganisms decompose tissues and organs ­
produces gasses which cause bloating. Skin blisters and falls off
Few weeks ­ tissues liquefy and seep into the area around the body
Few months ­ years ­ skeleton remains
Decades ­ centuries ­ skeleton disintegrates ­ nothing left

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Forensic entomology:
2 main ways ­ succession and life cycles of insects
Succession:
As a body decays, the populations of insects on it change ­ there is a succession in
species. The community of species present when the body is found allows the stage
of succession to be determined and…

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Genetic identification
Polymerase Chain Reaction (PCR):
Allows small samples of DNA to be amplified for use during DNA profiling, meaning
that forensics only need small DNA samples such as a strand of hair.
A cycle of temperature changes results in huge numbers of DNA fragments being
produced.
1) Place a…

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DNA profiling/DNA fingerprinting:
To identify genetic information
Everyone's DNA is unique because of the variety of the DNA sections not
used to code for proteins (introns)
Look for short repeated sequences in introns (short tandem repeats)
Mini satellites contain 20 ­ 50 base pairs
Micro satellites contain 2 ­ 4…

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Teeth and fillings decay slowly, they are resistant to burning. A forensic dentist makes
a chart of the teeth, including dental work, fillings and missing teeth. This is
compared to dental records. The forensic dentist may also look at the development
of the teeth to determine the age.

Summary of…

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Conjugation ­ some bacteria can transfer their chromosome to a recipient bacteria

Viruses:
Smallest living organism
No cell wall, cell surface membrane, organelles or cytoplasm
Obligate parasites ­ cannot reproduce without a host. Invade other cells and
take over their biochemistry to make more viruses
Nucleic acid core (DNA or…

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they remain dormant but if the person's immune system is weakened these
bacteria become active and divide
this leads to active TB ­ lung tissue is slowly destroyed by the bacteria
causing symptoms of: breathing problems, coughing up blood in sputum,
suppression of immunity, weight loss, poor appetite, fever and…

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But as the virus leaves the T cell, it destroys the cell membrane killing the
host cell - this reduces the number of T cells in the body reducing immunity

Difficult to create a vaccine for AIDS because:
virus mutates rapidly
therefore antigens on the viral surface continually change
working…

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won't recognise other strains with different antigens ­ has to produce a
primary response for each new strain

The carbohydrate present in storage granules is glycogen.

BARRIERS TO PATHOGEN ENTRY
Pathogens enter through areas not covered by skin ­ nose, mouth, eyes, gas
exchange surfaces, gastrointestinal tract and genital tract…

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neus3

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sara10

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Wiinsy

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