3.2.4 Flashcards
What impacts do antibodies have on antigens (4)
- Inactivation
- Agglutination
- Phagocytosis
- Produce compliment proteins
How do antibodies inactivate antigens
They bind to + neutralise bacterial toxins
What’s agglutination
When antibodies force pathogens to clump together making them a bigger target for phagocytosis
What do compliment proteins do
Attach to antibody antigen complexes and get broken into smaller fragments eventually being able to burst the pathogen membrane
What does the humoral response include (3)
Production of antibodies
B lymphocytes
T helper lymphocytes
Example of a cell that may have more than 1 type of antigen on the surface
Bacterial
What are monoclonal antibodies
An antibody from 1 WBC that’s extracted and cloned
What white blood cells are used for monoclonal antibodies
B-lymphocytes (produce antibodies)
What can you do with monoclonal antibodies if u know the correct antibody the body needs to fight a particular pathogen
They can be injected into a patient with the disease to help fight it
What do antibodies have that’s complementary to 1 specific antigen
A specific shape
What can some monoclonal antibodies bind to on chemicals
e.g of chemicals
Receptor sites on chemicals
E.g toxins produced by bacteria
How can monoclonal antibodies be injected into patient
Using a syringe/needle/pen
Why are monoclonal antibodies difficult to obtain
As b lymphocytes don’t divide easily (mitosis)
How are monoclonal antibodies made (7)
- Mouse exposes to non-self antigen to stimulate mouses B-cells
- B-cells extracted from mouses spleen
- B cells fused with tumour cells so mitosis can continue
- Detergent added to break down membranes so B cells + tumour cells can fuse forming a hybridoma
- Hybridoma cells are separated + cloned, the clones are tested. The correct clones are cloned on a larger scale + purified
- Antibodies are modified to be more like human cells (humanisation)
- Monoclonal antibodies are injected into patient
Why are mice used to obtain monoclonal antibodies
Small
Cheap
Reproduce quickly
What are b-lymphocytes extracted from the mouse in
The spleen (blood sample with lots of plasma that gets separated)
What are B cells fused with so mitosis can continue outside the body
Tumour cells - divide quickly and can be easily grown in a lab
What is added to break down cell membranes of B cells and tumour cells so they can fuse
Detergent
What’s a B cell and tumour cell fused together called
Hybridoma
What’s humanisation
When antibodies can be modified to make them more like human cells before they’re used
3 uses of monoclonal antibodies
Cancer treatments
Diagnosis
Pregnancy tests
What do cancer cells have that’s different to healthy body cells due to mutation in their dna
Different antigens on their surface
How are monoclonal antibodies used to treat cancer (4) - type of blocking
- Isolate + clone antibody complementary to cancerous cells antigen
- Inject into patient
- Antibodies bind to cancer cells
- Antibodies block chemical signals so stop uncontrolled growth in cancer cells
What do antibodies do when they bind to cancer cells
Block the chemical signals that cause uncontrolled growth in the cancer cells
What’s. An advantage of treating cancer with monoclonal antibodies
It ignores the rest of the healthy body cells, unlike chemotherapy and radiotherapy
How are monoclonal antibodies used to treat cancer (5) - attatching
- Specific antibody is isolated and cloned
- Radioactive/cytotoxic marker is attached to antibody
- Antibodies inserted
- Specifically attach to cancerous cells only
- Radioactive/cytotoxic component kills the cell
What type of marker is attached to an antibody to kill cancerous cells
Radioactive/cytotoxic marker
E.G.s of diseases monoclonal antibodies are used to diagnose
Flu
Cancer
Hepatitis
Chlamydia
What is used to identify chlamydia
Fluorescent antibodies complimentary to the antigen on the bacteria that causes chlamydia
How can scientists predict if a man has prostrate cancer using monoclonal antibodies
As men with prostrate cancer produce high PSA levels, so the antibodies specific to PSA can identify it
What do monoclonal antibodies bind to for diagnosis
Hormones/chemicals in the blood to measure their levels
What can monoclonal antibodies test during diagnosis
Test samples for specific pathogens
What does the placenta produce that’s present in the urine of a pregnant woman
HCG
What do home pregnancy tests contain
Monoclonal antibodies complimentary to the HCG that have blue beads attached to them
How does a coloured line appear in a pregnancy test
As the HCG antibody complex travels down the stick until it’s trapped by another antibody
How do pregnancy tests work (5)
- Woman urinates on the stick with antibodies in it
- HCG hormone binds to the antibodies with the blue beads
- Urine travels up the stick carrying the antibodies with the blue beads
- The hormone/bead/antibody bind to more antibodies attached to the strip in the stick
- The blue beads get stuck to the strip turning it blue
What shows a positive result that you’re pregnant on a pregnancy test
2 lines
What happens if you’re not pregnant but still urinate in the stick
Urine still travels along stick with blue beads but there’s nothing to stick the blue beads to the test strip do it won’t turn blue
What’s the order of the displays on a pregnancy stick going down
Control window
Results window
Reaction zone
How would u know the pregnancy test is faulty
If there’s no line in the control window
3 advantages of monoclonal antibodies
Are specific, only targeting cancerous cells
Cheap to use
Can be used in smaller doses
Fewer side effects than chemotherapy/radiotherapy
What’s the main disadvantage of monoclonal antibodies
There are possible side effects e.g fever, vomiting, low blood pressure
Why are monoclonal antibodies not widely used as treatments as hoped
As they have more side effects than initially expected
What are polyclonal antibodies
The mixture of different antibodies produced by different types of B cells due to microbes having for than 1 type of antigen on their surface
2 hazards monoclonal antibodies have caused (ethical issues)
Deaths - virus that attacks the brain
Organ failure
What’s a big concern with the production of antibodies
That cancer is induced in mice - animal misuse in medical research
Example of natural passive immunity
Factor of natural passive immunity
When mother passes antibodies to specific pathogens to a foetus through the placenta + to their children through breast milk
Temporary
What’s natural active immunity
When offspring must make their own antibodies when exposed to microbes (pathogen) to have memory cells
How are antibodies made in artificial active immunity
Vaccinations
What are the 2 types of active immunity
Natural active immunity
Artificial active immunity
What’s passive immunity like
Passed onto you giving instant protection
What’s active immunity
Body working to protect you as come into contact with pathogen and fight it off
What could vaccines contain (1 of 5)
- Weakened (attenuated) strain of microbe
- Dead microbe
- Modified toxins of bacteria
- Isolated antigens
- Harmless bacteria genetically modified to carry pathogens’ antigens
What does attenuated mean
Weakened/reduced
What does a vaccination consist of
What is a vaccine
Needle + fluid
Material inside needle that stimulates primary response
What productions do vaccines stimulate
What does this mean
Stimulate memory cells production
So if you’re exposed to actual pathogen, the secondary response will be strong enough to prevent illness
What’s herd immunity
When a large proportion of the community are vaccinated, so this reduces chance of a pathogen being transferred (majority vaccinated)
Why is herd immunity important
As it’s not possible to vaccinate everyone
What must a successful vaccination programme have (4)
- Limited side effects
- Technology to produce, store + transport vaccine
- Not cost too much
- Trained staff must be available to administer vaccine
If a vaccine has limited side effects what does this mean
More people will be willing to have vaccination
Why are diseases rarely completely eradicated (6)
- Vaccine may not work on some compromised immune systems
- Some may get disease before vaccination has time to work
- Not enough people have vaccine
- Pathogen may mutate a lot
- People my not get vaccine for religious/ethical regions
- Some pathogens ‘hide’ inside cells/ in intestines so are difficult to get vaccines against
E.G.s of compromised immune systems that vaccines might not work on
Cancer
Diabetes
What disease has pathogens that mutate a lot
Flu
In what disease do pathogens hide in the small intestine
Cholera
Which immune response is more rapid and why
Secondary immune response
So you don’t get ill
When may the antibodies produced by B cells no longer work and vaccines become useless
What’s this called
If the pathogens antigens change due to its DNA mutating as B cells are specific to 1 antigen
Antigenic variability
Example of a retrovirus
HIV (human immunodeficiency virus)
What enzyme is in HIV
Reverse transcriptase enzyme
Explain HIV replication
- HIV protein binds to CD4 protein on t helper cells
- HIV capsid fuses with cell membrane (membranes fuse) so RNA and enzymes enter t helper cell
- Reverse transcriptase changes HIV RNA -> DNA
- HIV DNA inserted into T cell DNA
- Produces mRNA which instructs cell to make viral proteins
- New HIV particles leave T helper cell using cell membrane as vesicle
What protein on t helper cells does HIV protein bind to
CD4 protein
What does reverse transcriptase enzyme do in HIV replication
Changes HIV RNA -> DNA so it can be read and used by the cell
Where in the cell does mRNA instruct it to make viral proteins
At t helper cell ribosomes
How do HIV particles leave the t helper cell
Vesicles
Why can’t you get ride of t helper cells yourself
As it only targets t-helper cells
On a graph how would u recognise if aids has developed due to t helper cells
If number of t helper cells reduces
What does AIDS stand for
Acquire immune deficiency syndrome
What 2 cells does AIDs kill/disrupt
T helper cell
Memory cells
Why is a decrease in t helper cells disadvantageous (2)
Less B cells are made to produce antibodies
Less cytotoxic T cells made
Why is a decrease in memory cells disadvantageous
Less able to launch secondary immune response
What test relies on monoclonal antibodies
The Elisa Test
What does the Elisa test stand for
Enzyme-linked immunosorbent assay
What antigen does the Elisa test use
Antigen of HIV
Examples of diseases the Elisa test is use to detect
HIV
Cancers
Tuberculosis
What’s the Elisa test procedure (10)
- Antibodies to pathogen bound to slide/ plate well
- Blood sample added
- Antigens of pathogen bind to antibodies
- Antigens that don’t bind are washed out
- More antibodies are added + enzyme is attached (also bind to HIV)
- Enzyme-antibody binds to antibody-antigen complexes in well
- Unbounded antibodies removed/washed out
- Colourless substrate of enzyme added
- Enzyme converts into coloured product
- Sample colour change if positive test
What test does the Elisa test have a similar principle to
Pregnancy test
