T5: Infection And Immunity Flashcards
4 types of forensic identification
Dental records
Fingerprints
Blood groups
DNA profiling
Uses of DNA profiling
Identify fluids/individuals
Paternity testing
Track genetic relationships
Paternity’s testing process
DNA band sequence
23 bands (13 loci, 2 chromosomes)
Half align with mother half align with father
DNA profiling gene used
Intron non coding block
Short tandem repeat
2-50bps
Same locus of homologous chromosomes
Different no. Repeats
Different combination of bps
13 loci used
DNA splicing
mRNA —> mature mRNA
Only exons left
DNA profiling process
DNA sample (blood/skin/semen)
STRs extracted using restriction enzymes/amplified with PCR
Fragments separated using gel electrophoresis
Fragments stained
13 loci bands compared
DNA gel electrophoresis process
DNA in gel well (agarose)
Voltage applied
-DNA—> anode
Smaller fragments?no. Repeats faster
Comparison ladder
Compare base pairs
Use X-ray, fluorescence, DNA stain
Polymerase chain reaction
Amplify DNA sequence, make millions of copies from a small sample
25-30 cycles
DNA sample, free DNA nucleotides, DNA primers, DNA polymerase
Desaturated at 95C, H bonds broken, DNA —> ss
Annealing, 55C, 26 primers bind
Elongation, 70*C, DNA synthesis
Virus structure (5)
Some
Receptor proteins
Lipid envelope
Enzymes
All
Protein coat
Nucleic acid
Bacterial cell wall types
Gram +
Cell membrane, thick peptidoglycan
Gram -
Cell membrane, thin peptidoglycan, outer membrane
Compare and contrast viruses and bacteria
V, B
Size: 20-200nm, >1mm
Genetic material: RNA/dsDNA/ssDNA, dsDNA
Membranes: lipid envelope, membrane bound
Need a host cell, can live independently
Name 5 ways of determine time of death
Body temp
Degree of muscle contraction
Extent of decomposition
Forensic entomology
Stages of successio
Body temperature TOD
Normal 36.5-37.5
Respiration stops
Temperature becomes ambient
Factors (size, position, clothing, wind speed, ambient temp, humidity, air vs water)
Muscle contraction TOD
Rigor mortis
ATP need myosin to make actin
Stop respiration
Muscles dont have ATP, fix
Starts 2-4hrs
Finishes 6-8hrs
Starts in face goes down
Muscle fibres breakdown last
Warm, not stiff
Warm, stiff
Cold stiff
Cold not stiff
Extent of decomposition TOD
Bacteria/fungi metabolise tissue
Enzymes digest tissue
Lysosomes rupture
Breakdown cells w enzymes
Anaerobic conditions
Gas forms blisters and bloating
Colour change greenish
Putrefaction, decomp and breakdown, more liquid in corpse
Forensic entomology TOD
Bacterial decomp
Attract insects
Pioneer species lay eggs due to smell/moisture
Maggots feed on tissue
3-4 waves
Increase no. Species
Food source runs out
Succession
Name 4 infection barriers
Skin keratin
Skin flora
Gut flora
Stomach
How is skin keratin an infection barrier
Tough
Waterproof
Prevent pathogen netry