Immunity Flashcards
What is a monoclonal antibody
Antibodies that have the same tertiary structure and are produced by cloning of plasma cells (B-cells)
2 examples of using monoclonal antibodies in medical treatments:
Cancer treatment -> antibodies are injected into blood, and they bind to specific cancer cell’s antigens and block it from reproducing
–> diagnosing disease, pregnancy test,
–>medical diagnosis/ cancer testing
–>passive immunity vaccines.
Describe the role of antibodies in producing a positive result in an ELISA test?
1st antibody binds/attaches to complementary antigen shapes that are bound to test plate.
2nd antibody with an enzyme attached is added to the test plate and attaches to this antigen ( the 1st antibody-antigen complex formed in step 1)
The solution/substrate is added and will change colour once it has binded with the enzyme attached.
Why was the amount of antibody given to the mice calculated in g per kg of body mass. Explain why the dose was calculated per unit mass?
To take into account the different masses of mice.
Explain how antibodies are produced when the mice were injected with sheep red blood cells?
Sheep red blood cells have antigens on their surface, which activate B-cells with specific complementary receptors, causing them to differentiate into plasma cells and produce antibodies.
Explain why, in a test strip test, which is using monoclonal antibodies to detect disease, the antibodies only bind to specific antigens.
Antibody found in blood/sample in the test is only complementary to the binding site shape of the antigen found on the test plate.
Explain why it is important to have a control line in a test strip, which is using monoclonal antibodies to detect a disease.
Prevents a false negative result because the antibody found in the blood sample had moved up the test strip and has not bound to any other antigens on the test strip that would indicate a positive test.
How would you join the points on a plotted graph?
Straight lines point to point as it would be impossible to predict the intermediate values between the points
Describe the role of macrophages in stimulating B lymphocytes.
Is an antigen in membrane presented to B lymphocytes
Or
produces cytokinins
Explain how antigenic variability causes some people to become infected more than once with influenza viruses?
Memory B-cells do not recognise new antigens, and so the antibodies shape that is previously produced is no longer complementary to the new antigen.
Describe how bacteria are destroyed by phagocytosis
Bacterial pathogen releases chemicals that attract phagocyte towards it.
Phagocyte engulfs pathogen and forms phagosome.
Lysosomes bind to phagosome and release contents into it, enzymes/lysozymes
That digest/hydrolise the bacteria.
An antigen in a vaccine leads to the production of antibodies. Describe the part played by B- lymphocytes in this process?
Phagocyte presents antigens to B lymphocytes.
Antigen binds to the complementary receptors on the B-lymphocytes
Lymphocytes become activated and cause themselves (B-lymphocytes) to reproduce by mitosis and undergo clonal selection
Forms plasma cells that secrete the antibodies into blood and memory cells.
Describe how giving a HPV vaccine leads to the production of antibodies against HPV?
Vaccine contains antigen from HPV
They are displayed on antigen presenting cells
Specific T-helper cells detect antigen and stimulate B-cells to divide by mitosis and clone to give plasma cells
Plasma cells produce antibodies that have specific complementary binding sites to the HPV antigen and these are secreted into the blood.
How does a vaccine work?
Vaccine contains antigen from sed disease e.g.. HPV virus
Displayed on antigen presenting cells
specific T-helper cells detect antigen and stimulate B-cells to divide by mitosis and clone to form Plasma cells and memory cells
Plasma cells produce antibodies with specific complementary binding sites to the antigen of the sed disease cell e.g. a bacterial cell, HPV virus.
Give 3 ways a doctor could use base sequences to compare different types of one virus e.g.. HPV virus type 1, 2 and 3
Compare base sequences of DNA
Look for mutations
Compare base sequences of mRNA
Main components of HIV are:
Capsid,
Phospholipid membrane (bilayer),
Why might a person with HIV develop a large number of infections about 9 years after he became infected with HIV?
HIV virus remains dormant and it only exists as DNA in host DNA
HIV destroys T-cells in body
So more free viruses are produced and this leads to fall in number of T-cells
Fewer T-cells can activate B-cells to divide by mitosis to form memory cells and plasma cells therefore antibody production is reduced
immune system not working properly cos has inability to fight infections
How does a DNA virus work?
The attachment protein of the DNA virus binds to the receptor on a human cell this binding allows DNA to enter the cell.
DNA is injected into the cell and joins the DNA in the nucleus of the cell.
The virus DNA is turned into messenger RNA (mRNA), so the ribosomes make more viruses which eventually burst out the cell because there are so many and they will go out and spread and bind to more human cells due to having the same receptors.
This forms a DNA viral disease.
What is reverse transcriptase used for in HIV RNA?
To turn HIV RNA into HIV DNA
How do RNA VIRUSES work?
E.g. HIV
The attachment protein of the RNA binds to the receptor only found on the T helper cells. The RNA is injected into the T helper cells. Alongside the RNA reverse transcriptase is (and enzyme) is injected. This enzyme makes DNA from RNA, using the DNA nucleotide from the host cell. (Cell the virus is infecting). This DNA is single stranded and is called complementary DNA. The virus uses DNA polymerase and more DNA nucleotides to form the second strand of DNA to make it double stranded so that it can join to the host cells DNA in the nucleus
Bacterial pathogens
Release toxins and divide
Viral pathogens
Replicate inside cells
HIV to aids process
When you are HIV positive you have the HIV virus in your body and it will only be in the T helper cells. It will lie dormant and then suddenly start to replicate after a while. It then attacks lots of T helper cells. The person will get aids because without the T helper cells they cannot fight off all the infectious diseases that the body normally fights.
How can HIV be thwarted into forming AIDS?
Aids can be thwarted by using antiviral drugs these drugs stop viruses replicating and therefore prevent HIV developing into AIDS however they have horrible side effects so most patients end up stopping using the drugs and end up with aids.
Humoral Response
Produces antibodies to kill pathogens
Cell-mediated response
Stimulates T killer cells which kill our own cells containing viruses such as this mediated response being used to kill cancer cells.
It still stimulates B cells to make antibodies however this is not as important.
It can prevent the spread of cancer by cytotoxic T cells killing cancer cells or it can also kill receptors on organs provided by organ donors it does this because the receptors on foreign organs are foreign so the host must have immunosuppressive drugs to stop the cytotoxic T cells killing these receptor.
Immune response
Production of antibodies in both cell mediated and humour humoral responses
Antibody does what?
It doesn’t kill or destroy it’s binds to the pathogen and that enables it to kill and destroy the pathogen
2 types of viruses
RNA VIRUS
DNA VIRUS
WHAT IS A VIRUS
A virus has proteins on its surface called attachment proteins which are complementary to specific receptors found on specific cells
For example the HIV virus has attachment proteins which can only bind on receptors found on the surface of T helper cells
During phagocytosis the lysosomes … with the phagosome ?
Fuse to release lysozymes,
it does not bind to the phagosome it FUSES,
At the end of Phagocytosis what is displayed on the cell surface membrane of the phagocyte?
Antigens are placed on the cell surface membrane of the phagocyte
B-lymphocytes Vs T-lymphocytes
B- Matures in bone marrow
involved in humoral immunity
produces antibodies
responds to foreign material outside the body cells (in the blood)
Responds to bacteria and viruses
T- Matures in thymus gland
Involved in cell-mediated immunity
responds to foreign materials inside the body cells
responds to own cells altered by viruses or cancer and to transplanted tissues.
Secrete perforin
Can stimulate other cells in the immune response ( e.g. phagocytosis)
Both involved in the destruction of pathogens/foreign antigens
What is an antibody and what does it do?
A protein consisting of four polypeptide chains : 2 long chains and 2 short chains.
Its function is to identify and neutralise foreign antigens such as bacteria and viruses
How does the structure of an antibody allow it to carry out its function?
Combining sites 3D shape is specific to one type of antigen and allows the antibody to attach due to the complementary shape
variable region has a different amino acid sequence this alters the tertiary structure as it creates different ionic, disulfide or hydrogen bonds within the protein this changes the shape of the antigen binding site so that it is specific to one type of antigen
The hinge region allows movement so it can bind to different antigens. It does this by allowing the antibody to change position and therefore attached to two antigens forming an antigen antibody complex
Explain why a single pathogen may cause a polyclonal response?
Pathogen must display more than one different type of antigen on the surface
Ethical issues with production of monoclonal antibodies/ or vaccination process
Available to all regardless of cost
vaccines tested on animals
side effects are long term risks
vaccine may contain pig products-religious objections
3x different types of ways that antigens are administrated during a injection vaccine
e.g. measles or polio
1) Attenuated vaccine use heat treated pathogens which are weakened
2) Dead microorganisms unable to reproduce
3) isolated antigens via cell surface proteins or antigens.
Why might vaccination not eliminate disease? Like flu even though we have memory cells for Flu already?
Because some pathogens like influenza viruses are constantly changing their surface antigens this means that our immune system does not recognise them and so the antibodies produced to bind to them are not complementary and so we have to start the whole process again this means the response is slower and so we will get ill
Factors to consider for a successful vaccination programme?
1)Availability of vaccine and trained medical staff
2)Some people are immunosuppressed for HIV or Autoimmune diseases
3)Not everyone is vaccinated.
4) large quantities available at low cost
5) few side effects
6) vaccine can be produced and transported and stored hygienically
7) all or most population is vaccinated
Active immunity
injection of antigens which stimulates the immune response (requires energy to synthesise the antibody)
Passive immunity
injection of ready made antibodies (does not require energy) also when antibodies are received by the placenta or breast milk
Herd immunity
Vaccination of a sufficient proportion of individuals in a population at one time so that transmission of a particular pathogen is interrupted
How do vaccines prevent you from developing a particular disease (6marks)
Vaccines contain antigens of dead/weakened pathogens And these are injected
memory cells are made
on 2nd exposure memory cells produce antibodies and become active by recognising pathogens
rapidly producing antibodies at a quicker and larger rate
these antibodies destroy pathogens such as bacteria or viruses
herd a fact-fewer people to pass on the pathogen
How HIV CAUSES DISEASE?
How is HIV spread
Blood, sharing needles for drug use, blood transfusion
perinatal transmission, across the placenta during pregnancy, during childbirth or via breastfeeding
wounds, bites, puncture with sharp objects such as a needle in a workplace
semen, through anal sex, vaginal or oral sex
Why are antibiotics ineffective against viruses?
Viruses lack cell structures that are targeted by antibiotics E.g. some antibiotics bind across the ribosome and inhibit protein synthesis.
How to treat viruses?
Only a few drugs that are available to treat viral diseases this is because
they are difficult to reach as they reproduce inside the cells
it is also expensive and
viruses have a higher mutation rate so the drug becomes ineffective
