Cell recognition and the immune system (Chapter 5)
State two differences between a specific and a non-specfic defense mechanism
- The response for non-specific is immediate while the response for specific is slower and takes roughly 2-3 weeks
- The response for non-specific is the same for all pathogens while the response for specific is specific to each pathogen
After a pathogen gains entry to the body it is often a number of days before the body's immune system begins to control it. Suggest a possible reason for why this is so.
ADD ANSWER
After a pathogen gains entry to the body it is often a number of days before the body's immune system begins to control it. Suggest why it would be inaccurate to say that the body takes days to 'respond' to the pathogen.
- Body responds immediately by 'recognising' the pathogen and by phagocytosis
- The delay is in building numbers of lymphocytes and THEREFORE CONTROLLING THE PATHOGEN
What is a pathogen?
A microorganism that causes disease
What are the two types of defense mechanisms?
Specific and non-specific
What is immunity?
The body is better prepared to destroy a pathogen the next time it experiences it.
Define what an antigen is
An organism or susbtance, usually a protein that can be recognised as foreign by the immune system and therefore stimulates an immune response
Name 2 similarities between T and B cells
- Both are types of white blood cells
- Both produces from stem cells in the bone marrow
State 2 differences between T and B cells
- T cells mature in the thymus gland while B cells mature in the bone marrow
- T cells are involved in cell mediated immunity while B cells are involved in humoral immunity
From your knowledge of cell- mediated immunity and lung structure suggest why humans infected with the H5N1 virus may sometimes die from suffocation
- The virus infects the lungs
-Leading to massive production of T cells
- Accumulation of these cells may block the airways/ fill the alveoli
- Which May cause suffocation
Suggest why any spread of bird flu around the world is likely to be rapid
- Birds carry the H5N1 virus and they can fly vast distances across the world in a very short space of time
Explain why the secondary immune response is much more rapid than the primary one (4 marks)
- In the primary response, the antigens on the pathogen have to be ingested, processed and presented by B cells;
- They then need to divide by mitosis to produce plasma cells and memory cells;
- Whereas in the secondary immune response, memory cells are already present;
- so the only process is dividing by mitosis to produce plasma cells and memory cells this means a quicker response
Contrast the cell-mediated and humoral responses to a pathogen (4 main points)
Types of cells
- Cell mediated involves T cells whereas humoral involves mostly B cells
Antibodies
- No antibodies involved in cell mediated , antibodies are produced and secreted in humoral (by plasma cells)
Stage of immune response
- Cell mediated is the first stage of immune response and humoral is the second stage of immune response after cell- mediated stage
Effective where
- Cell mediated is effector through body cells; whereas humoral is effective through bodily fluids
Suggest 3 cell organelles that you might expect to find in large quantities in a plasma cell and explain why
- RER and ribosomes = make and transport the proteins of the antibodies
- Golgi apparatus = sort, process and compile the proteins
- Mitochondria = to release the energy needed for such as massive antibody production
Suggest why antibodies made of proteins, rather than carbohydrates or fats, are more likely to be effective against a wide range of diseases.
- There must be a massive variety of antibodies as each responds to a different antigen, of which there are millions.
- Only proteins have the diversity of molecular structure to produce millions of different types
Distinguish between an antigen and an antibody
- Antigen is a molecule that triggers an immune response by lymphocytes
- An antibody is the molecule that has the complementary structure shape to the antigen and is produced in response to it
Discuss whether drug trials should be limited to volunteers who are terminally ill with a conditions that the monoclonal antibody is designed to treat.
- Argument in favour = removes risks of healthy volunteers being harmed and terminally ill patients have most to gain and less to lose
- Argument against = response of terminally ill might be different from those in the early stages of the disease and results therefore could be unreliable as the sample size is likely to be smaller
Distinguish between active immunity and Passive Immunity
Active Immunity: Individuals are stimulated to produce their own antibodies and the immunity is long-lasting
Passive Immunity: Antibodies are introduced from outside rather than being produced by the individual and the immunity is only short-lived
Explain why vaccination programmes against the influenza virus may not be effective
- Influenza viruses can display antigenic variability
- its antigens change frequently due to virus mutating frequently
- and so antibodies of the immune system no longer recognise the virus
- Therfore new vaccines are require to stimulate the antibodies that complement the new antigens
Among other places, lysozyme are found in tears. Suggest why?
- The protective covering of the eye, and especially the tear ducts are potential entry points for pathogens
- The eyes are vulnerable to infection because the coverings are thin to allow light through
- Lysozyme will break down the cell walls of any bacterial pathogens
- And so destroy them before they can cause harm
Explain why HIV is called a retrovirus
- It possesses both RNA and reverse transcriptase
- Which can make DNA from RNA
- A reaction that is reverse and is carried out by transcriptase
Distinguish between HIV and AIDS
- HIV is a virus (human immunodeficiency virus)
- AIDS (aquired immunodeficiency syndrome) describes the condition caused by an infection with HIV
Tuberculosis (TB) is a lung disease spread through the air. Suggest a possible reason why the widespread use of condoms might help reduce the incidence for TB in a population
- widespread condom use prevents HIV infection
- reduces AIDS development and immune system impairment
- higher TB risk in AIDS patients
- impaired immune systems, like AIDS, increase TB vulnerability and transmission
Suggest why antibodies made of proteins, rather than carbohydrates or fats, are more likely to be effective against a wide range of diseases.
- There must be a massive variety of antibodies as each responds to a different antigen, of which there are millions.
- Only proteins have the diversity of molecular structure to produce millions of different types.
Explain how the use of the detergent in monclonal antibody formation is effective in changing membrane structure allowing the B cell to fuse with tumour cell
- It will affect the lipid component of the membrane
- Causing them to develop holes
- When the detergent is washed out, membranes will reform sometimes in combination with those of the cells adjacent
Explain why we agitate the mixture when detergent is added (P2 for Explain how the use of the detergent in monclonal antibody formation is effective in changing membrane structure allowing the B cell to fuse with tumour cell)
-To ensure the B cells and tumour cells are repeatedly coming into physical contact
-This is essential if they are to fuse
Explain why cells from cancer tumours used to fuse with B cells
- Because B cells cannot survive outside body long and do not divide outside he body
- Tumour cells are long lived and divide outside the body
- Using both of them lead to long-lasting B cells that can be grown outside the body
Suggest which other cells are likely to fuse together as well (Part 2 of Explain why cells from cancer tumours used to fuse with B cells)
- Cells can sometimes form membranes with neighbouring cells
- e.g., B cells with other B cells
- e.g.,tumour Cells with other tumour Cells
Explain why it is necessary to modify the antibodies from mouse tissue
- Because monoclonal antibodies from mouse tissue will be recognised as foreign (non-self) and will be destroyed by human antibodies if not humanised
Another way of eliminating the need for humanisation would be to inject humans with an antigen and then extract the antibodies produced in response to it ; Suggest 2 reasons why this would be considered unethical
- Introduction of antigen into humans could cause a reaction/ disease that could be dangerous
- The antigen could stimulate an over response of the immune system
Autism experts point out hay many symptoms of autism first occur around the age of 14 months. Explain why this information is relevant to the debate on whether MMR vaccine and autism are linked.
- MMR vaccine is given around 12-15 months
- The same time as autism symptoms appear
Discuss how an organisation funding research might influence the outcome of that research without dishonestly altering the findings (4 points)
- It might present the findings in an incomplete biased fashion
- or ignore unfavourable findings (eg risks to an individual )
- Fund only further research that seems likely to produce the evidence that its seeks rather than investigating all possible outcomes
- Withdraw funding for research that seems likely to produce unfavourable findings
What is necessary for scientific theories to be treated with caution (4 points)
- To be universally accepted, as a scientific theory if must first critically appraised and confirmed by other scientists in the field the confirmation of a theory takes time peer reviewed
- Scientists personal beliefs, views and opinions may influence the way they approach or represent their research
- the facts, as presented by media headline writers, companies, governments and other organisations, may have been biased or distorted to suit their own interest
- New knowledge may challenge accepted scientists beliefs; theories are being modified all the time