Infection, Forensics Immune System Flashcards
explain how changes in the blood vessels results in reddening and swelling around the site of inflammation
- histamine is released from mast cells as a result of damaged tissue
- causes vasodilation
- increases blood flow
- vasodilation also causes permeability of capillaries to increase
- allowing blood plasma to leave capillary/enter tissues causing swelling
Describe how HIV particles are able to enter T helper cells.
- glyocproteins/GP 120 on the surface pf the virus
- bind to CD4 receptors on the surface of T helper cells
- viral envelope fuses with cell membrane of T helper cell
- viral RNA enters cell
Explain why destruction of T helper cells causes symptoms of AIDS
- reduces cytokine production
- therefore reducing cloning/activation of B cells
- reducing antibody production
- there is an increased risk of opportunistic infections
bacteriostatic antibiotic
a substance which can prevent the multiplication of bacteria
Explain why the presence of microorganisms on the skin and in the gut helps to
prevent pathogenic organisms multiplying in the body.
- flora in gut and skin are better adapted to the conditions
- therefore they can outcompete pathogenic organisms
- bacteria in the gut secrete chemicals/lactic acid that help destroy pathogens
why may stem cells from bone marrow prevent HIV causing AIDS
- stem cells can differentiate into specialised cells
- can differentiate into T helper cells that are resistant to HIV
- T helper cells are destroyed by HIV so the patient cannot produce an immune response
- mutated CD4 receptor prevents HIV entering the T helper cells
- T helper cells are not destroyed therefore AIDS does not develop
A person who has been vaccinated becomes infected with HPV. Explain the role of the T
cells in the body of this person
- vaccinated person has T memory cells
- these recognise antigens specific to the virus
- T helper cells activate T killer cells/B cells
- T killer cells destroy cells infected with the virus
why is there few bacteria in the stomach
- pH inside stomach is too low for enzymes of most bacteria to function
- bacteria that live in stomach have adaptations that enable them to survive
HIV structure
- protein capsid
- two strands of RNA
- spherical
interferon
produced by infected cells and inhibits viral replication
Fewer virus particles produced to infect other cells
explain the role of T cells in the immunity to a virus after vaccination
- T cells bind to antigen on APC
- production of active T helper/memorycells
- these activate B cells to divide/become cells capable of producing antibodies
- memory cells remain in body so antibodies can be produced quickly on re-infection
vaccines type of immunity
artificial active
ribosomes of bacteria
smaller than ribosomes in eukaryotes
infection control practices hopsitals have introduced
- doctors don’t wear long sleeves
- disinfection of beds
- hand wash
explain how skin flora protects body from infection
- prevents growth of pathogens
- competition for nutrients / space/ water
- release of chemicals/toxins/antimicrobials
why is applying antihistamine cream better than taking antihistamine tablets
- local reaction produced
- cream applied to actual site of histamine production
- more rapid treatment
- higher concentration of antihistamine at site
- antihistamines will not be digested by enzymes
Suggest why common cold viruses cannot infect cells if they land on unbroken skin.
skin is a barrier
keratin
lack of receptors for virus
Suggest why common cold viruses cannot infect cells if they enter the blood through a cut in the skin
virus only attaches to specific receptors
receptors not present on blood cells
state two characteristic features of antibodies
- produced by plasma cells
- agglutination
- glycoprotein
- Y shape
- antigen binding site
differences between genetic material of viruses and bacteria
- bacteria have dna and viruses have rna
- bacteria have circular genetic material while viruses are linear
- bacterial dna is double stranded while viral rna is single stranded
- bacteria may have plasmids and viruses do not
describe how macrophages ingest bacteria
phagocytosis
bacterium inside vacuole/phagosome
Lysosome fuses with the phagosome to form a phagolysosome
Lysozymes are released and destroy what was engulfed
Suggest why treatment with antibiotics may not be effective against dormant bacteria in tubercles
- bacteria need to be accessible to antibiotics
- bacteria inside macrophages
- waxy layer of bacteria
- antibiotic resistancd
How can a person develop artificial active immunity following vaccination
- dead pathogen put into person
- stimulated specific primary immune response
- T helper cells activated
- B h cell activated
- T killer cells activated
- memory cells produced
Explain why activity of these bacteria and inhibition of T cells means a person may quickly develop severe symptoms leading to death
Further ling damage/ severe breathing problems
Bacteria can get into blood
Organ failure leads to death
Reduced immune response due to a loss of T helper cells
Opportunistic infections causing death
role of DNA primers in amplification
primers have a specific base sequence
bind to complementary bases of the DNA to be amplified
provides a site for DNA polymease to bind to
why are amplified fragments for alleles different
base sequence of alleles are different
restricvtion enzyme cuts a specific site
only present in this specific allele
therefore allele is shorter
How to establish the time of death
record insects present at regular intervals of time
take into account stages of lifecycle present
Control temperature
Describe how DNA profiling could be carried out to show that these snakes are different
species.
DNA obtaijed from two different types of snake
PCR/restriction enzymes used to produce fragments of dna
gel electropheresis to analyse dna samples
this separates dna fragments
more differences in patterns of bands indicate snakes are differetn species
Describe the changes that occur inside a body in the first week after death
body temperature falls
rigor mortis
autolysis
putrefaction/bloating/discolouration
Describe the role of decomposers, such as microorganisms, in the carbon cycle.
break down organic material
they respire
releasing co2 into the atmosphere
explain electrophoresis
restriction enzymes cut dna into fragments
dna samples loaded onto agarose gel
electric crurent applied across the gel
markers used to visualise bands
Compare bands positions
Explain the effect of ambient temperature on the rate of decomposition.
increased rate of decompostion/decay
increased enzyme activity
increased growth rate of decomposers
Explain how microorganisms in the soil break down the stems (made of polysaccharides)
enzymes secreted by the microorgansims
break down glycosidic bonds
releases glucose that is used by the microorganism in respiration
Describe how one PCR cycle would increase the quantity of DNA present.
heat to 95 to break hydriogen bonds between dna
annealing/joingin primers at 55
elongating/addition of nucleotides
to double the quantity of dna
Explain the advantages for this species of blowfly of increasing the temperature within
the dead rhinos
increased enzyme activity
high temp denatures enzymes of other species
increases food availbility due to reduced competition
Explain why presence of microorganisms on the skin and gut helps to prevent pathogenic organisms from multiplying in the body
- Flora in gut and skin are better adapted to conditions
- Therefore they can outcompete pathogenic organisms
- Bacteria in the gut secrete chemicals which help to destroy pathogens
Describe how pre mRNA may be modified before being translated on the ribosome
- pre mRNA contains introns and extrons
- introns are removed and extrons are spliced together to produce a strand of mRNA
Explain why modification of pre-mRNA enables one gene to give rise to more than one protein
- different exons can be removed
Therefore producing different sequences of amino acids
Describe how clinical trials of a vaccine would be conducted
- tested on small group of healthy patients
- tested for presence of antibodies on virus
- group of people at risk of contracting disease are given vaccine
- Number of people who develop viral disease are monitored
Describe how DNA profiling could be carried out to show that these snakes are different species
- DNA obtained from 2 types of species
- Restriction enzymes to cut DNA fragments
- Gel electrophoresis is used to analyse DNA samples
- Gel electrophoresis is used to separate the fragments of DNA
- more differences in the pattern of bands produced would indicate that they are different species
Explain how these two species of snake could have arisen from a common ancestor
- mutation leads to variation
- natural selection led to one species surviving to reproduce
- giving rise to two populations with differing alleles
- 2 populations became reproductively isolated
- sympatric speciation
Autolysis
Break down of cells by enzymes in body
explain why following a vaccination, children should repeat other vaccinations they have had
loss of memory cells so no secondary immune response
therefore antibodies can’t be produced
less immunity to diseases previously vaccinated against
need to repeat vaccinations to produce memory cells
explain why dormant bacteria are not destroyed by the immune system
bacteria are inside macrophages
bacterium has thick, waxy cell wall
lyosomes can’t fuse with phagocytic vacuole
bacteria within tubercule can’t be destroyed
Bacteriostatic
Number of bacteria stays the same. Prevents multiplication of bacteria
Bacteriocidal
Kills bacteria as bacteria number decreases
Describe how one PCR increases quantity of DNA present
Heat to 90C to break hydrogen bonds between DNA strands
Annealing of primers at 55C
Elongating by adding nucleotides
DNA polymerase forms phosphodiester bonds
Doubled quantity of DNA
Explain advantages for flies of increasing temperature within dead animals
Increases enzyme activity for species
High temperature denatures enzymes of other species
Increases food availability by reducing competition from other species/decreasing rate of decomposition in animals
Injection
Artificial passive
Vaccine
Artificial acrive
Breastmilk
Natural passive
