Topic 2C: Cells and immune System Flashcards
What is herd immunity
When those who aren’t vaccinated are protected against as most of the population in vaccinated so less people catch it from
What’s a disadvantage to taking vaccines orally
It could be broke down by enzymes in the gut or be too large for it to be absorbed into the blood
Name and explain an ethical issue surrounding vaccines (2)
All vaccines are tested on animals before humans and these may have side effects for people making them reluctant to take it
What is antigenic variation
When some pathogens change their surface antigens so the memory cells from the first reaction doesn’t recognise them
What are the different strains of influenza known as…
Immunologically distinct
What’s an ethical issue with monoclonal antibodies
Animals rights issues and used to produce the cells
What does HIV stand for
Human immunodeficiency virus
What does AIDS stand for
Acquired immune deficiency syndrome
What is AIDS
Condition where the immune system deteriorates and eventually fails
What’s the cellular response
T-cells and other immune system cells they interact with
What’s the humoral response
B-cells and clonal selection and the production of MCA’s
Explain the primary response
when antigens enter the body for the first time activating immune system
It’s slow as there isn’t many B-cells making the antibodies bind to it
Person shows signs of disease
After being exposed to the antigen T and B cells produce memory cell
Explain the secondary response
If the same pathogen enters the body again, immune system will produce a quicker, stronger immune response
Clonal selection occurs faster, memory cells are activated dividing into correct plasma cells producing correct antibodies
No symptoms shown
What is active immunity
Type of immunity when you immune system makes its own antibodies after being stimulated by an antigen
What’s a natural example of active immunity
Becoming immune after catching the disease
What’s an artificial example of active immunity
When you become immune after being given a vaccination
What’s passive immunity
Type of immunity you get from being given antibodies make by a different organism
What’s a natural example of passive immunity
When a baby becomes immune due antibodies it received from its mother
What’s an artificial example of passive immunity
When you become immune after being injected with antibodies from someone else
Name 3 other characteristics of active immunity
Requires exposure to antigen
Takes awhile for protection to develop
long-term as memory cells are produced
Name 3 other characteristics of passive immunity
Doesn’t requires exposure to antigen
Protection is immediate
Short-term as memory cells aren’t produced
What’s a vaccination
An ingestion containing dead or weakened form of a pathogen (antigen) causing your body to produce memory cells against the pathogen
How are monoclonal antibodies formed
Activated b-cells divided into plasma cells which secrete loads of antibodies which are specific to particular antigen (MCA)
What’s agglutination
An antibodies has 2 binding sites, so can bind two pathogens at the same time becoming clumped together
What’s a T-cell
Type of WBC, it has receptor proteins on its surface that bind to complementary antigens on pathogen (activating t-cell)
Name 2 types of T-cell
Helper and Cytotoxic T-cells
What do helper t-cell do
T helper cells released chemical signals that activate and stimulate phagocytes and T-cells
What do cytotoxic t-cells do
Kill abnormal and forging cells also activating b-cells
What are B-cells
WBC covered in antibodies
What’s clonal selection
When antibodies on the surface of B-cells meet a complementary shaped antigen, it binds to it
This together with substances released from helper T cells activated b-cells
What do b-cells divide into
Plasma cells
What are antigens
Molecules that can generate an immune sytem
What are pathogens
Organisms that cause disease
What are toxins
Poisons, not cells there molecules
Name 4 main stages of immune response
Phagocytes, t-cells, b-cells and antibody production
What is a phagocyte
WBCs that carries out phagocytosis
Explain phagocytosis
1) phagocyte recognises the foreign antigens on the pathogen
2) cytoplasm of pathogen moves round the pathogen, engulfing it
3) pathogen contained in a phagocytise vacuole
4) lysosomes fuses with vacuole, breaking down the pathogen, digestive enzymes lysosomes do this
5) phagocyte then presents pathogens antigens, activating other immune responses
How does AIDS progress
Initial symptoms include minor infections of mucus membranes recurring respiratory infections later on TB
Chronic diarrhoea in the lasts stages toxoplasmosis
How do antibiotics kill bacteria by interfering
Kill bacteria by interfering with their metabolic reactions
How does HIV infect out cells
Infects t helper cells which act as a host cell for the virus
Affecting the effectiveness of the immune system
How do people infected with HIV develop AIDS
When the he,per T cells number in the body reach a critically low level
What’s reverse transcriptase needed for
Viral replication
What’s the envelope in HIV made from
Made from membrane stolen from cell-membranes of a pervious host cell
Explain how HIV replicates
1) attachment protein attachments to a receptor molecule on the cell membrane of the host Th cells
2) capsid is released into the cell where it uncoats and releases the genetic material into cells cytoplasm
3) Inside the cell, reverse transcriptase is used to make a complementary stand of DNA from the viral RNA template
4) Double stranded DNA is made and inserted into human DNA
5) Host cell enzymes are used to make viral proteins from viral DNA in the human DNA
6) Viral proteins are assembled into new viruses, which bud from cells and infect others
Explain how to target a particular substance for medical diagnosis (pregnancy testing)
1) Application area contain antibodies for hcg bound to a colour bead (blue)
2) when urine is applied to application area any hcg will bind to the antibody on the beads, forming AA complex
3) When the urine moves it caries the beads up the test strip with it
4) test strip contains antibodies to hcg that are immobilised
5) if hcg is present the test strip turns blue, as the immobilised antibody binds to any hcg concentrating the hcg antibody complex with the blue beads attached. If no hcg is present, the beads will pass through the test trip without binding to anything and so it wouldn’t go blue
Explain how we can target drugs to a particular cell type (cancer)
1) different cells in the body have different surface antigens
2) cancer cells have antigens called tumour markers that aren’t found on normal body cells
3) Monoclonal antibodies can be made that will bind to the tumour markers
4) You can also attach anti-cancer drugs to the AB’s
5) when the AB’s come into contact with the cancer cells they will bind to the tumour markers
6) meaning the drugs only accumulate in the body where the cancer cells are
7) means side effects are lower in this treatment
Explain the ELISA test (HIV)
1) HIV antigen bound to the bottom of a well plate
2) sample of patients blood plasma which might contain several different antibodies, is added to the well if there are any HIV-specific antibodies they will bind to HIV antigen stuck to the HIV antigen stuck to the bottom of the well. well is washed out to remove any antibodies that unbound
3) Secondary antibody that has a enzyme attached is added to the well it can bind to HIV specific antibody well is washed again to remove any unbound secondary antibodies
4) solution is added to the well containing a substrate which is able to react with the enzyme attached to the secondary antibody to produce colour change (indicating HIV infection)
