Infection Immunity and Forensics

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  • Created on: 03-01-13 10:36
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Infection, immunity and forensics
Fingerprints are unique to an individual and don't change over a lifetime
Four main types of fingerprint ­ arch, tented arch, whorl and loop
Dental records are the best way of identification fillings and teeth decay very slowly and are
resistant to burning.
DNA profiling, apart from identical twins, all DNA is unique. Study short tandem repeats
DNA profiling
DNA sequences are repeated many times, known as short tandem repeats or satellites
Contain 2 to 50 base pairs with 5 to 100's of repeats
STR are at the same loci on both chromosomes of a homologous pair
Repeats at a locus varies from individual and the base sequence
Obtain the DNA through biological tissue and broken down in a buffer solution with detergent to
disrupt the membranes
DNA Fragmentation
DNA fragmentation with enzymes
Use of restriction enzymes which cut at particular sequences of bases
Restriction enzymes ­ endonucleases found IN a cell
Genetic manipulation through cutting a section out of a length of DNA which can be used as a
vector or for genetic screening
Bacteria protect their own DNA with restriction enzymes as they change the bases in the
sequence that their own restriction cells target
DNA is copied using polymerase chain reaction (PCR)
The process uses DNA primers with fluorescent tags to position either end of the STR
Separation of fragments by Gel electrophoresis according to size
Fragments move through a stable medium and connected to electrodes
DNA has a negative charge and moves to the positive
Southern blotting transfers fragments to more resilient membranes, Fragments stay in position
but are denatured
DNA probe added and located to find a region of DNA needed
Use of profiling
STRs are inherited like alleles, gaining one from each parent
Can be used for identification, paternity disputes, stolen animals and variation in evolution
Used for legal proceedings
A result that is unique to the individual
Not very reliable for closely related criminals
Time of death
Determined by body temperature, rigor mortis, decomposition and entomological evidence
Body temperature
Body temperature, the core body temperature changes to that of the environment
Used to determine time of death upto 24 hours
Body size, position, clothing, air movement, humidity and temperature affect the rate of
temperature change

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Rigor mortis
Muscle tense and then relax
They tense do to the lack of ATP being produced so the myosin cannot let go of the
Muscles are starved of oxygen and oxygen dependant reactions stop so respiration is anaerobic
(lactic acid is made), pH falls so enzymes no longer work and ATP isn't produced to relax the
Rigor mortis, starts with small limbs and gradually gets to larger limbs
Rigor mortis stops as muscle tissue stats to break down
Remain in this state…read more

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Reproduce asexually by binary fission replication of DNA they divide identically
TB carried in droplets of mucus and saliva (droplet infection), can remain airbourne for hours in a
poorly ventilated room
Poor diet, poor health and overcrowded living conditions increase the risk of getting TB
Can survive on bedclothes and in the room due to hard standing capsule
Strand of nucleic acid enclosed in a protein coat.…read more

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Each b cell produces only one type of antibody, so each antigen will bind to activate different B
Produced in bone marrow, each divides rapidly to produce a clone of cells, B cells have
receptors on their surface these include transmembrane versions of the antibody molecules
they produce
T lymphocytes
Are produced in the bone marrow but mature in the thymus gland (hence T for Thymus)
T cells each have one specific type of antigen receptor on their surface and only bind to the…read more

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Humans inherit some antigens that the body recognises but also rejects
Xenoplantation ­ no common antigens so the body rejects by the primary response
Response to TB
Tb a contagious diseases caused by bacterium mycobacterium tuberculosis.…read more

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Undergoes protein synthesis and buds out by exocytosis, taking the coat of the T helper cells
and killing them as they leave
Active phase when the person is first infected with HIV, HIV antibodies appear, fever, sweats,
headache and sores, rapid replication of virus and loss of T helper cells, T helper recognised as
infected and T helpers are destroyed
Chronic phase virus reproduces rapidly and system tries to control it, more colds, more
infections, dormant diseases can reactivate, 711 years, infected T helper increases…read more

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Reverse transcriptase inhibitors prevent RNA making DNA for integration into the hosts
o Protease inhibitors that catalyse the cutting of large into small for new virus
TB can be treated with antibiotics, usually a combination of 4 given over a long period of time.
This ensures the dormant bacteria are destroyed
Different types of antibiotics that work in different manners
o Bactericidal antibiotics that destroy bacteria
o Bacteriostatic prevent multiplication of bacteria help the immune system destroy the
pathogens.…read more


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