Immune Defences And Phagocytosis Flashcards
What are the 2 types of the immune system ?
Specific
Non-specific
Define immune system.
A system of biological structures and processes that protect against disease by identifying and killing pathogens and tumour cells.
Define pathogen
Any microorganism capable of causing disease.
Define antibody
A protein produces by the lymphocytes in response to the presence of the appropriate antibody.
What is the function of lysosomes.
Contain digestive enzymes which break down worn out organelles and dead cells.
Define antigen
Found in the cell surface of pathogens and triggers an immune response by the lymphocytes.
Which biological molecule is found on the cell surface of pathogens ?
Antigens.
Which protein is produced by the lymphocytes and is is part of the immune system.
Antibody.
What is a microorganism capable of causing disease called.
Pathogen
What are the stages of defence.
- Prevent invasion - physical barrier
- Non-specific attack phagocytosis
- Specific attack- lymphocytes.
Name some physical barriers.
Skin Goblet cells Collin Stomach acid Ear wax Tears
How does the skin act as physical barrier.
It is waterproof and prevents pathogens entering the blood stream.
How are goblet cells physical barriers.
They produce mucus which contains a lot of protein. Invaiding pathogens get stuck in this mucus.
How do Cillia act as a physical barrier ?
Hair like projections which beat rhythmically to move mucus back up the trachea.
How do tears act as a physical barrier.
Contain lysozyme enzyme which breaks down the bacterial cell walls.
Outline how physical barriers prevent pathogens which enter via the airway.
Goblet cells produce mucus in the trachea. Mucus contains a lot of proteins.
Cilia best rhythmically to move mucus up the trachea.
Mucus is then swallowed down the oesophagus.
Bacteria reach the hydrochloric acid in the stomach which causes the tertiarry structure of the pathogen to denature.
What is phagocytosis.
A process which can attack any pathogen by a type of endocytosis. Phagocytes.m search the body for “non-self material”.
Explain, in detail, the process of phagocytosis.
All pathogens release chemoattractants which we attracted by phagocytes.
Phagocytes recognise this as a ‘non-self’ cells and begin to engulf the pathogen because the phagocyte and pathogen have complimentary shapes.
Cytoplasm of the phagocyte surrounds the pathogen engulfing it by endocytosis this forms a membrane bound pocket called a phagosome.
Pathogen is hydrolysis inside the phagosome and products are absorbed by the Cytoplasm.
What type of enzymes do lysosomes contain ?
Hydrolitic digestive
What is an attenuated microorganism ?
A weakened organism.
Describe how memory cells protect the body from disease.
On further exposure to the same microorganism, the antigen is recognised therefore a greater production of antibodies is produced for a faster response
Why did the number of people with whooping cough increase during the 1980s.
There was a reduction in the number of people being vaccinated yet there was an increase in birth rate.
Why may using vaccines with attenuated or dead microorganisms be a problem for patients.
The process of killing the microorganisms may not be 100% efficient and full blown diseases may be caused.
Attenuated organisms are non-virulent but may become virulent.
Side effects such as allergies could occur
Immunity may decline due to a change in the antigen so boosted injections may be needed.
What is the definition of virulent.
Extremely severe side effects.
Why does taking plant antibodies not create long term disease production ?
This is a passive process meaning the person is not creating antibodies or replacing antibodies therefore no memory cells are produced.
Explain the advantages of using plant antibodies over antibodies produced in experimental animals.
There is fewer ethical difficulties and less chance of infection.
How should a control group for a vaccine be treated ?
Injected with saline that doesn’t contain an antigen.
Why is a control group needed ?
To compare the results with your data to see any trend
Explain the advantage of giving the percentage of people with a disease as well as the total number.
Allows a comparison to be made as different numbers of people may have been treated.
Why are vaccines often most effective with young people ?
They have not yet been exposed to the disease and therefore have no natural immunity.
Explain why girls are vaccinated against Rubells when they are young.
They must be vaccinated before pregnancy so that the baby does now gain rubella or become immune.
Why are young boys vaccinated against rubella ?
Makes are vaccinated so they are not a source of infection for unprotected females.
What is a poliomyelitis antigen ?
A glycoproteins molecule on the surface of the virus which stimulates an immune response and antibody production.
Why do some vaccines not give long lasting protection ?
If passive immunity has occurred meaning that it is a secondary response and although antibodies have been produced rapidly, memory cells have not been activated.
What is an antigen (Mark scheme).
A glycoproteins molecule which stimulates an immune response.
What are lymphocytes ?
A type of white blood cell which attack non-self molecules as they recognise pathogens by a complimentary protein antigen on the surface.
How do lymphocytes recognise pathogens ?
By recognising a complimentary antigen on the cell surface of the pathogen.
Give examples of lymphocytes.
T cells and B cells
Where are T cells produced and matured ?
Produced in the bond marrow then migrate to the thymus gland where they mature.
What type of immunity do T-cells allow.
Cell-mediated immunity therefore they only respond to antigens that are attached to a body cell.
Which type of lymphocytes undergo cell mediated immunity ?
T cells
What is cell-mediated immunity.
Where T cells only respond to antigens that are attached to body cells.
What is a helper T-cell ?
Binds to antigens presented on body cells.
Activated other T cells to divide rapidly by mitosis and create clones.
The clones can then develops into memory cells, stimulate phagocytes to engulf pathogens, stimulate B cells to divide or kill infected cells by becoming cytotoxic.
What can clones T cells become
They can develop into memory cells which help long term immunity.
They can stimulate phagocytes to engulf pathogens.
They can stimulate B cells to divide by mitosis.
They can kill infected cells by becoming cytotoxic.
What do T cells need to become to kill infected cells.
Cytotoxic
What type of lymphocytes are most effective against viruses
T-cells
Where are B cells produced and matured ?
Produced in bone marrow.
Matured in bone marrow.
What type of immunity do B cells undergo and what is this ?
Humoural immunity
B cells ingest the invading pathogens which are floating in the extra cellular fluid and cytoplasm. They then become an antigen presenting elm by outing part of the antigen on their surface. The T-helper cell then attached to the antigen causing the B cell to divide into memory or plasma cells
What is humoural immunity ?
B cells ingest pathogens which are floating in the cytoplasm and extra-cellular fluid.
They then become an antigen presenting cell by putting part of the antigen on their surface. The T-helper cell then attached to the antigen causing the B cell to divide into memory or plasma cells
Draw a diagram of an antibody and label it.
In notes
What does the variable region of the antigen allow ?
The variable region allows different antibodies to be complementary to the specific antigen.
Why does an antibody have disulfide bonds ?
Holds the peptides together
Explain the polypeptide chains within an antibody.
2 long heavy chains - constant regions which are the same in all humans.
2 light chains.
What are the functions of antibodies.
Causing agglutination
Neutralisation
How do antibodies cause agglutination and why ?
Makes microbes stick together making it easier for the phagocytes to engulf them. Therefore they act as markers for the phagocytes to engulf them.
How do antibodies cause neutralisation and why ?
Antibodies attach to the toxins produced by the pathogens therefore neutralising the toxins and making them un-harmful.
How do antibodies affect viruses ?
Viruses have proteins on their surface which recognise and bind to receptors of the host (body) cell. These antibodies hen prevent viruses entering the cells by binding to the viruses themselves.
What is it called when many different types of antibodies are cloned ?
Polyclonalantibodies
What are polyclonalantibodies ?
Many different types of antibodies
Suggest why antibodies are made from proteins
Because using proteins allows infinite number of variable regions as the specific folding of amino acids creates specific shapes.
Why could a single type of bacterium stimulate many different B cells to divide and produce many different clones of antibody producing plasma cells
Bacterium have many different antigens on their cell surface therefore many different B cells are activated to produce clones for every antigen type.
What are monoclonal antibodies.
A single type of antibody produced from one type of plasma cell.
How are monoclonal antibodies used to treat cancer cells.
Monoclonal antibodies are produced that are complimentary to cancer cell antigens. These antibodies are given to patients and attach themselves to the receptor cells of the cancer cells. This therefore blocks the chemical signals that stimulate uncontrolled cell growth.
How are monoclonal antibodies used for medical diagnosis.
Some diseases produce a high level of specific antigens. Therefore adding monoclonal antibodies are put into the blood to interact with the antigens to help measure the level of a disease a person has.
How are monoclonal antibodies used for pregnancy tests.
Monoclonal antibodies present on the pregnancy test strip are linked to colour particles. If hCG is present in the urine it binds to these antibodies creating a colour complex which moves along the strip to create a coloured line.
What is HCG
A hormone produced by the placenta that becomes present in the urine when a woman is pregnant.
What is lag phase ?
The time it takes for the primary immune response to occur whilst specific, complimentary B cells are found.
What stimulates production of memory cells in the body ?
Antigens
What different things can be contained in vaccines ?
Part of the nucleic acid bass of the pathogen.
Antigens from the pathogen if the pathogen is weak.
Protein sections of the pathogen
Or toxoids
What do toxoids do ?
They counteract bacterium with harmful toxins.
What May using only some protein sections of the harmful pathogen not be useful in vaccines ?
It may not stimulate enough of an immune response
What is herd immunity ?
Most people are immune and have vaccines therefore can’t catch it from people around them.
What is ring immunity ?
Isolate person and whoever had been near them is given a vaccine.
How do vaccines work ? Detail
Dead or weakened pathogens are added by subcutaneous injection. T and B cells are then produced which produce antibodies. The correct B cells and antibodies are identified and memory cells are left in the blood.
If you are exploded to a live pathogen, a secondary response will rapidly occur and symptoms will not occur.
Memory cells recognise pathogens quickly and divide into plasma cells which produce antibodies.
How and what do memory cells divide to create.
Memory cells divide into plasma cells which produce antibodies by mitosis.
What is a subcutaneous injection ?
An injection which goes under the dermal layer, into the fat.
What is antigenic variation ?
Pathogens can have genetic mutations which is called antigenic variation meaning that upon secondary infection, the memorycells do not recognise the antigen. This makes vaccine development very difficult
What makes vaccine development difficult ?
Antigenic variation where genetic mutations of the pathogens occur meaning that memory cells do not recognise the secondary exposure of the antigen.
Give examples of antigenic variation.
HIV, influenza
What is active immunity ?
Your immune system makes its own antibodies after being stimulated by antigens.
What is natural active immunity and give an example.
Standard production of memory cells in the body.
Give an example of artifical active immunity.
Vaccines.
What is passive immunity.
Antibodies are made by other organisms and are given.
Give an example of natural passive immunity
Mother gives child antibodies via placenta before they are exposed to the antigen.
Give an example of artificial passive immunity.
Antitoxins or antivenoms are given.
Contrast how active and passive immunity act time wise
Active has a lag time
Passive is immediately into the blood
Explain the difference in the exposure required to continue active and passive immunity
Active requires exposure to the pathogen
Passive does not
Explain the difference in the lasting time of active and passive immunity.
Active is long term because memory cells are produced.
Passive is short term because no memory cells are produced.
Give two structures a bacterial cell may have that a while blood cell does not have
Flagellum
Capsule
Pillus
What proves that an antibody has a quaternary structure ?
It will have multiple polypeptide chains joined by disulfide bonds
Give two ways in which pathogens can cause disease when they enter the body of their host.
Damaging your own cells
Releasing toxins
Describe how B-lymphocytes respond when they are stimulated by antigens.
When B lymphocytes are stimulated they divide by mitosis to create clones. These then become memory cells which help long term immunity or plasma cells which releases complimentary antibodies so that complex’s can be made.
Explain how antigenic variability has caused people to become infected with a virus more than once.
The T and B cells do not recognise the new antigens as their tertiary structure has changed meaning that the antibodies are no longer complimentary and no complex can be made.
Describe how macrophages stimulate B lymphocytes.
They are an antigen in the membrane presented by lymphocytes and produce cytokinins.
What does HIV stand for ?
The Human Immunodeficiency Virus
What does AIDS stand for ?
Acquired immune deficiency syndrome
What does HIV virus attack ?
T and B cells which are lymphocytes of the immune system.
What does HIV virus attacking T cells cause ?
This prevents the simulation of B cells meaning that no antibodies are produced from plasma cells.
Phagocytes are not activated to engulf the pathogen.
What does HIV virus attacking B cells mean ?
Memory cells are destroys and therefore a loss of immunity to the specific pathogen occurs.
What is a retro virus.
Contains reverse transcriptase and therefore catalysed the production of DNA to RNA.
What concerts RNA to DNA ?
Reverse transcriptase
What type of virus can convert virus DNA from our own RNA ?
A retro virus because it contains reverse transcriptase
What quantified if you have HIV
You have HIV when your T cell count falls below a certain value.
What are the components in the structure of a virus.
Attachment proteins Matrix Reverse transcriptase Lipid envelops Capsid RNA
What do the attachment proteins on a virus do ?
Allow the virus to attach to host cells.
What does the lipid envelope of a virus do ?
Surrounds the cell
What does the capsid of a virus do ?
Encloses the genetic material.
What does RNA stand for ?
Ribonucleicacid
Which is a genetic material
How does HIV replicate (in detail):
HIV enters the blood stream
An attachment protein on the HIV binds to a protein called CD4 on the T helper cells.
The capsid fuses with the T cell membrane. RNA and enzymes of HIV enter the T helped cell.
Reverse transcriptase converts RNA into DNA.
The DNA is moved into the T-helper cells nucleus and uses the cells ribosomes to make HIV proteins.
The new DNA created mRNA using the cells enzymes. This contains the instructions for making new viral proteins.
mRNA passes out of the nucleus and uses the cells ribosomes to make HIV proteins.
HIV proteins break away from the t cell with a piece of its cell membrane , forming its own lipid envelope.
What does the ‘ELISA’ diagnosing test stand for ?
Enzyme linked immunosorbent assay.
Give other purposes of the ELISA test.
Tells you if a hormone is present in the blood stream and if so how much
Used for drug testing
What is the ELISA test ??
A test that uses antibodies , an enzyme and a colour change to identify an antigen.
Explain in detail how the ELISA test is carried out.
Add plasma blood sample to a well.
If present, HIV cells will stick to the bottom of the well.
The well is washed to remove any unattached HIV antigens.
An antibody, specific to the antigen, is added and given time to bind to the antigens.
The well surface is then washed again to remove any unattached antibodies.
A second antibody with enzymes added, which is complimentary to the antigen is added and given time to bind.
The surface is again washed to remove any unattached second antibody.
A colourless enzyme substrate is added. The enzyme breaks down the substrate into coloured products.
The amount of HIV antigen present is indicated by the colour intensity.
Give two structures a bacterial cell may have that a while blood cell does not have
Flagellum
Capsule
Pillus
What proves that an antibody has a quaternary structure ?
It will have multiple polypeptide chains joined by disulfide bonds
Give two ways in which pathogens can cause disease when they enter the body of their host.
Damaging your own cells
Releasing toxins
Describe how B-lymphocytes respond when they are stimulated by antigens.
When B lymphocytes are stimulated they divide by mitosis to create clones. These then become memory cells which help long term immunity or plasma cells which releases complimentary antibodies so that complex’s can be made.
Explain how antigenic variability has caused people to become infected with a virus more than once.
The T and B cells do not recognise the new antigens as their tertiary structure has changed meaning that the antibodies are no longer complimentary and no complex can be made.
Describe how macrophages stimulate B lymphocytes.
They are an antigen in the membrane presented by lymphocytes and produce cytokinins.
What does HIV stand for ?
The Human Immunodeficiency Virus
What does AIDS stand for ?
Acquired immune deficiency syndrome
What does HIV virus attack ?
T and B cells which are lymphocytes of the immune system.
What does HIV virus attacking T cells cause ?
This prevents the simulation of B cells meaning that no antibodies are produced from plasma cells.
Phagocytes are not activated to engulf the pathogen.
What does HIV virus attacking B cells mean ?
Memory cells are destroys and therefore a loss of immunity to the specific pathogen occurs.
What is a retro virus.
Contains reverse transcriptase and therefore catalysed the production of DNA to RNA.
What concerts RNA to DNA ?
Reverse transcriptase
What type of virus can convert virus DNA from our own RNA ?
A retro virus because it contains reverse transcriptase
What quantified if you have HIV
You have HIV when your T cell count falls below a certain value.
What are the components in the structure of a virus.
Attachment proteins Matrix Reverse transcriptase Lipid envelops Capsid RNA
What do the attachment proteins on a virus do ?
Allow the virus to attach to host cells.
What does the lipid envelope of a virus do ?
Surrounds the cell
What does the capsid of a virus do ?
Encloses the genetic material.
What does RNA stand for ?
Ribonucleicacid
Which is a genetic material
How does HIV replicate (in detail):
HIV enters the blood stream
An attachment protein on the HIV binds to a protein called CD4 on the T helper cells.
The capsid fuses with the T cell membrane. RNA and enzymes of HIV enter the T helped cell.
Reverse transcriptase converts RNA into DNA.
The DNA is moved into the T-helper cells nucleus and uses the cells ribosomes to make HIV proteins.
The new DNA created mRNA using the cells enzymes. This contains the instructions for making new viral proteins.
mRNA passes out of the nucleus and uses the cells ribosomes to make HIV proteins.
HIV proteins break away from the t cell with a piece of its cell membrane , forming its own lipid envelope.
What does the ‘ELISA’ diagnosing test stand for ?
Enzyme linked immunosorbent assay.
Give other purposes of the ELISA test.
Tells you if a hormone is present in the blood stream and if so how much
Used for drug testing
What is the ELISA test ??
A test that uses antibodies , an enzyme and a colour change to identify an antigen.
Explain in detail how the ELISA test is carried out.
Add plasma blood sample to a well.
If present, HIV cells will stick to the bottom of the well.
The well is washed to remove any unattached HIV antigens.
An antibody, specific to the antigen, is added and given time to bind to the antigens.
The well surface is then washed again to remove any unattached antibodies.
A second antibody with enzymes added, which is complimentary to the antigen is added and given time to bind.
The surface is again washed to remove any unattached second antibody.
A colourless enzyme substrate is added. The enzyme breaks down the substrate into coloured products.
The amount of HIV antigen present is indicated by the colour intensity.
Describe the structure of an anitbody.
Antibodies are quaternary proteins Made up of 4 polypeptide chains 2 long heavy , 2 short light chains Held together by disulfide bonds Constant region the same in all antibodies Variable region contains specific receptor site Each antibody specific to an antigen They are flexible so can bind precisely.
What are the main functions of antibodies ?
Cause agglutination -making pathogens stock together so they can be engulfed.
Act as markers - stimulating phagocytes to engulf cells.
Neutralise toxins to prevent them causing harm
Bind to viruses to prevent infections.
