Topic 6 Forensics and immunology Flashcards
List the ways in which time of death can be determined
Forensic entomology,
Rigor Mortis,
Body temp
Explain how the rate of cooling of a body can be used to determine time of death.
After death, oxygen does not get pumped to cells so they stop respiring, therefore not producing heat energy, so the body will cool to ambient temp over time. by comparing the dead body temp, to the ambient temp of the area found, you can determine how long since the cell death
Describe the stages of rigor mortis
Muscles contract, lack of atp energy means muscles cannot uncontract and so stay locked up. Eventually muscle fibres get decomposed and so release after a period of time.
Explain why rate of decomposition can be affected by environmental temp
Increasing temp increases decomposer bacteria enzyme activity by causing more successful enzyme substrate collisions therefore increasing rate of respiration and therefore increasing rate of decomposition, up to the optimal enzyme activity temp at which point the rate decreases due to enzymes denaturing.
Microorganisms use polymers in organic matter as a source of glucose for respiration, Explain how microorganisms break down cellulose and lignin in plant material.
Secrete enzymes which breaks down glycasidic bonds between glucose monomers, turning it into smaller molecules they can then use in respiration.
Explain why decomposition can contribute to the greenhouse effect
Decomposition breaks down long chain glucose polymers which are then respired by bacteria, producing CO2 which contributes to greenhouse effect
State the name of the process of separating DNA into visible blots
Electrophoresis
Describe how you would carry out electrophoresis
Add amplified DNA to wells in gel, place electrodes with the negative electrode closest to the wells and the positive electrode furthest from the wells. Turn on electrodes and let the DNA travel, turn off electrodes and add a stain that shows DNA under UV light
Explain why DNA travels to the positive electrode in electrophoresis
DNA is negatively charged, so electrostatic forces cause DNA to travel towards the positive electrode as opposite charges attract
Explain how the size of the DNA fragment determines how far it moves through gel in electrophoresis
Gel contains a small mesh which causes larger DNA fragments to get caught in the mesh, so smaller fragments travel faster through the mesh
Describe the structure of HIV
2 Strands of viral RNA, Reverse transcriptase and Integrase enclosed in a protein capsid which is enclosed in a Lipid envelope with GP-120 glycoproteins attached.
Explain how HIV infects its host cell and produces new HIV particles
gp120 protein on the lipid envelope of the virus binds to the CD4 receptor on the T helper cell
Fuses with the membrane and releases the capsid contents via endocytosis
viral RNA binds to reverse transcriptase and produces viral DNA
viral DNA travels to cell nucleus and enters the genome via integrase action.
Cell produces viral RNA via transcription and viral protein via translation.
Virus capsid is formed and traveled to cell membrane
New virus lipid membrane is formed by budding where the new membrane is made from the cell membrane, causing damage to the cell membrane
Explain the impacts an HIV infection has on the immune system
Fewer Helper T cells means fewer cytokines released from cell so fewer B cells and Killer T cells activated therefore less antibodies produced and less infected cells killed, so body more prone to infection from other pathogens
An HIV infection has 3 stages, List these stages and explain why the final stage can result in the death of the individual infected
- Acute
- Chronic
- AIDS - Fewer T Helper cells therefore fewer cytokines released therefore less B cells and Killer T cells activated therefore less antibodies produced by B cells therefore weaker specific immune response so body is more prone to death from other pathogens.
Define the following:
A) Natural passive immunity
B) natural active immunity
C) Artificial passive immunity
D) Artificial active immunity
a) immunity gained by antibodies being passed from breast milk
b) Immunity gained by memory cells being formed after a pathogen invades the body.
c) immunity gained by addition of antibodies from anthropogenic sources such as blood plasma
D) immunity gained via memory cells being formed after exposure to a antigen via vaccine
