Topic 6: Immunity, infection and forensics Flashcards
Name the 4 ways of determining time of death of a mammal.
Extent of decomposition.
Forensic entomology.
Body temperature.
Degree of muscle contractions.
Describe how Extent of decomposition can be used to determine time of death.
Bodies follow same pattern of decay and decomposition.
Enzymes from digestive system from digestive system breakdown surrounding tissue.
Stage of decomposition can estimate time of death.
Describe how Forensic entomology can be used to determine time of death.
Each species of insect has specific life cycles.
Determining age of insects enables time of death to be estimated.
Body also acts of site of succession as species occupying it changes so analysis of community also estimates time of death.
Describe how Body temperature can be used to determine time of death.
Temperature of body decreases after death as Heat producing metabolic reactions stop.
Only use full up to 24 hours after death as body temp reaches surrounding.
Body position, surrounding conditions like weather will affect heat loss.
Describe how Degree of muscle contraction can be used to determine time of death.
After death muscles start to stiffen up as ATP is used up, calcium ions build up in muscles and become fixed in a state of contraction called rigor mortis.
starts 2-4 hours after death and ends around 36 hours after death.
Describe the Polymerase chain reaction.
DNA sample, primers, free nucleotides and DNA polymerase solution made.
Mixture is heated to 95 degrees breaking hydrogen bonds.
Mixture is cooled to 55 degrees so primers can bind to strands.
temperature is increased to 70 degrees as that’s when DNA polymerase works copying DNA.
This cycle is repeated many times.
Describe Gel electrophoresis.
DNA is cut with Restriction endonuclease enzymes.
Fragments placed in wells in agarose gels fluorescence are added.
Current is passed along gel.
DNA is negative so moves towards Anode.
Bigger fragments move slower as bands appear.
Differences between virus and bacteria.
Bacteria don’t require host virus do.
Bacteria only have DNA virus can have either DNA or RNA.
Viruses are significantly smaller than bacteria.
Bacteria have many cell membranes, cell wall, cytoplasm, ribosome plasmids, flagellum and pili viruses have none.
How TB infects humans.
First infection may be symptomless. Infected phagocytes ae sealed in tubercles in lungs.
Bacteria lay dormant not destroyed by immune system due to waxy coat.
When immune system becomes weak bacteria becomes active destroying lung tissue.
Can spread to other body parts becoming fatal.
Describe physical barriers to infections.
Skin tough physical barrier containing keratin.
Stomach acid and enzymes kills bacteria.
Gut and skin flora, natural bacteria competes with pathogens for food and space.
Name the 4 parts of the Non specific immune response.
Inflammation.
Fever.
Lysozyme action.
Phagocytosis.
Describe Inflammation.
Histamines released by damaged white blood cells causes vasodilation and permeability of blood vessels.
Increasing antibodies, white blood cells, and plasma going to infected tissue.
Describe Fever.
Hypothalamus sets body temp higher, increasing rate of enzyme-controlled reactions. slows rate of bacteria reproduction.
Balance must be struck to not denature own enzymes.
Describe Lysozyme action.
Lysozyme is an enzyme found in secretions like tears and mucus that kills bacteria.
Describe Phagocytosis.
Process in which Phagocytes engulf pathogens enclosing them in vacuole and exocytosis Lysosomes are entered with it.
