Cells (5) Cell Recognition And The Immune System Flashcards
The skin is a physical barrier to the entry of what?
Pathogens
There is a specific defence mechanism called what? (there are 2)
Cell mediated response and humoral response
Cell mediated response has what type of lymphocytes?
T lymphocytes
Humoral response has what type of lymphocytes?
B lymphocytes
To minimise the effect of this tissue rejection, donor tissues for transplants are normally what?
Matched as closely as possible to those of the recipient
Immunosuppressant drugs are often administered for what reason+
To reduce the level of the immune response that still occurs
Lymphocytes are not produced in response to an infection but that what?
They already exist
How many different types lymphocytes are found in a typical human body?
10 million
When a pathogen gets into the body, one of these lymphocytes will have a ______ on its surface that is _________________ to one of the proteins on the pathogen.
Protein, complementary
When an infection occurs, the one type already present that has the complementary _______ to those of the pathogen is ____________ to divide to build up its numbers to a level where it can be _________ in destroying it.
Proteins, stimulated, effective
_______ selection explains why there is _____ ___ between exposure to the pathogen and body’s defences bringing it under control.
Clonal, time lag
In the ____ these lymphocytes are constantly ________ with other cells
Fetus, colliding
Infection in the fetus is rare because it is ________ from the outside world by the mother and, in particular, the ________.
Protected, placenta
What is a phagocyte?
A type of white blood cell that engulfs, digests, and destroys pathogens
In phagocytosis, what is the first thing that happens?
Chemical attractants from the pathogen attract the phagocyte, causing the phagocyte to move towards the pathogen
In phagocytosis, what is the second step?
The receptors on the cell surface membrane of the phagocyte bind to the chemicals of the surface of the pathogen
In phagocytosis, what is the third step?
The phagocyte then engulfs the pathogen forming in a vesicle called a phagosome.
In phagocytosis, what is the 4th step?
Lysosomes move towards and fuse with the phagosome to form phagolysosome. Which then the lysosomes release lysozymes (hydrolytic ezymes) to catalyse the hydrolysis of the cell wall of the bacteria.
In phagocytosis, what is the last step?
Soluble products from the breakdown of the pathogen are absorbed into the cytoplasm of the phagocyte.
What is an antigen?
An antigen is a protein found on the cell surface membrane of a substance that is recognised as non self by the immune system and can trigger an immune response.
The presence of an antigen trigger the production of what?
Antibodies
Phagocytosis is specific or non specific response?
Non specific
A specific response is slower in action but provide long-term immunity. True or false?
True
What is a lymphocyte?
A type of white blood cell that produces antibodies
What are the 2 types of lymphocytes and where are they found?
T lymphocytes in the thymus and B lymphocytes in the bone marrow
T lymphocytes Is associated with cell mediated response. True or false?
True
B lymphocytes are associated with humoral response. True or false?
True
What is a pathogen?
A microorganism that causes disease
In cell mediated immunity, T lymphocytes respond to what?
Antigens found on the cell surface membrane of body cells.
In cell mediated immunity, what type of body cells can it respond to?
Virus infected cell, antigen presenting phagocytes, transplanted cells and cancerous cells.
In Cell Mediated Immunity, what is the first step?
Pathogens invade the body cells or are taken in by phagocytes.
In Cell Mediated Immunity, what is the second step?
The phagocytes place antigens from the pathogen on its cell surface membrane
In Cell Mediated Immunity, what is the third step?
Receptors on a specific helper t cell fit exactly onto these antigens.
In Cell Mediated Immunity, what is the Last step?
This attachment activates the T cell to divide rapidly by mitosis and form a clone of genetically identical cells
In Cell Mediated Immunity, the cloned cells can develop into memory cells that enable a rapid response to future infections by the same pathogen. True or False.
True
In Cell Mediated Immunity, the cloned cells can stimulate phagocytes to engulf pathogens by phagocytosis. True or False
True
In Cell Mediated Immunity, the cloned cells can stimulate B cells to divide and secrete their antibody. True or False
True
In Cell Mediated Immunity, the cloned cells can not activate cytotoxic T cells. True or False
False, they can activate cytotoxic T cells
How do cytotoxic T cells kill infected cells?
Produces a protein called perforin that makes holes in the cell surface membrane of the pathogen, allowing it to be freely permeable to all substances and dies as a result.
What is clonal selection?
A type of cell division to form a group of genetically identical cells, known as mitosis.
What is the origin of the term humoral immune response?
The origin term for bodily fluids is ‘humour’ which is derived from humour and produces antibodies in blood and tissues.
What is the key function of a B lymphocyte?
To produce specific antibodies that responds to one specific antigen
What is the role of a plasma cell?
Produce and secrete antibodies into blood plasma
How long do plasma cells last for?
A few days
How might a plasma cell be adapted for its function?
contains mitochondria, RER, protein synthesis occurs
What are the key differences between the primary and secondary immune response?
Primary - production of antibodies and memory cells
Secondary - secretion of a large quantity of antibodies at a faster rate and ensures the new infection is destroyed before harm.
In humoral immunity, what is the first step?
A virus infected cell is approached by a B cell. The B cell’s antibodies on the cell surface membrane bind to the antigens of the virus infected cell.
In humoral immunity, what is the second step?
Endocytosis occurs: B cell processes antigens from the pathogens from the virus infected cell an presents them on its surface (antigen presenting cell) and undergoes clonal selection
In humoral immunity, what is the third step?
The B cell with the antigen displayed on its surface binds to a specific Helper T Cell and undergoes clonal selection
In humoral immunity, what is the last step?
Plasma cells will produce and secrete antibodies, whilst memory B cells will remain in blood for many years to divide to form plasma cells.
In Cell Mediated immunity and Humoral immunity, antibodies are made in both responses. True or False
Yes
In Cell Mediated immunity and Humoral immunity, do they both have Helper T cells. Yes or No
Yes
In Cell Mediated immunity and Humoral immunity, are memory cells produced?
Yes
In Cell Mediated immunity and Humoral immunity, are cytotoxic T cells present in both responses? Yes or No
No, Cell Mediated immunity does have cytotoxic T cells present but Humoral immunity does not
In Cell Mediated immunity and Humoral immunity, does both responses undergo clonal selection? Yes or No
Yes
In Cell Mediated immunity it responds to any antigen in what?
blood or tissue fluid
In Humoral immunity it responds to specific antigens in what?
Body cells
What is an antibody?
A protein that has a specific binding site to antigens on pathogens and leads to the destruction of the pathogen. (synthesised by B cells)
What is an antibody made up of?
4 polypeptide chains - 2 heavy and 2 light, an antibody-antigen complex, variable region, constant region.
What is an antibody-antigen complex?
Where an antibody’s binding site fits precisely onto a specific antigen.
What is a variable region?
a binding site which is different on different antibodies
What does each specific binding consist of?
A sequence of amino caids that determine the tertiary structure of the antibody that binds directly to a specific antigen.
What is a constant region?
A region that binds to receptors on cells like B cells.
What kind of bonds are found in antibody ?
A disulphide bond/bridge
Antibodies prepare the antigens for destruction. True or False
True
What is agglutination?
Clumping of bacterial cells to make it easier for them to be located in the body as they are less spread out within the body.
What does a Marker do?
Stimulates phagocytes to engulf the bacterial cells to which they are attached.
What is a monoclonal antibody?
An antibody which has a been cloned
Monoclonal antibodies can be used to target specific substances and specific cells. True or False
True
What type of cell can monoclonal antibodies dedect?
Cancer cells
Monoclonal antibodies are produced that are specific to antigens on cancer cells. True or False.
True
Monoclonal antibodies are given to a patient and attach themselves to the receptors on their cancer cells. They will block chemical signals that stimulate their uncontrollable growth. True or false.
True
What is an advantage of direct monoclonal antibody therapy?
Since that the antibodies are not toxic and are highly specific, they lead to fewer side effects than other forms of therapy
What is indirect monoclonal antibody therapy?
An attachment of a radioactive or cytotoxic drug to the monoclonal antibody
Monoclonal antibodies are an invaluable tool in doing what?
Diagnosing disease with over a 100 different diagnostic products based on them
Monoclonal antibodies are used to in pregnancy testing kits. They present themselves on the test strip and are linked to what?
Coloured particles
If hCG is present in the urine, what happens?
It binds to these monoclonal antibodies
The hCG-antibody-colour complex moves along the strip until it Is trapped by a different type of antibody creating a colourled line. True or false.
True
What does hCG stand for?
Human chorionic gonadatrophin
An ethical issue of using monoclonal antibodies is that is involves the use of mice. Why is this an ethical issue?
Production of tumour cells involved deliberately inducing cancer in mice causing it to suffer.
An ethical use of using monoclonal antibodies is that the drug trials have led to patients to what?
Organ failure and potential death
In the process of producing monoclonal antibodies what is the first step?
Mouse exposed to a non self material which an antibody is required and B cells from mouse then produce mixture of antibodies which are extracted from spleen of mouse
In the process of producing monoclonal antibodies what is the second step?
The B cells are mixed with cells that divide readily outside of the body - like a cancer tumour
In the process of producing monoclonal antibodies what is the third step?
Detergent is added to the mixture to break down the cell surface membranes of both types of cell and enable them to fuse together to form hybridoma cells
In the process of producing monoclonal antibodies what is the fourth step?
The hybridoma cells are separated under a microscope and each single cell is cultured to form a clone. Each clone is tested to see whether it is producing the required antibody.
In the process of producing monoclonal antibodies what is the fith step?
Any clone producing required antibody is grown on large scale and the antibodies are extracted from the growth medium
In the process of producing monoclonal antibodies what is the last step?
They are modified to make then like human cells before they can be used. This is called humanisation
What is passive immunity?
It is an introduction of antibodies into individuals from an outside source
In passive immunity, immunity is acquired…
Immediately
In passive immunity, are memory cells made?
No
What is an example of passive immunity?
When anti venom given to victims of snake bites
What is active immunity?
It is when an individual stimulates the production of antibodies provided by their own immune system
Active immunity has two types, what are they?
Natural and artificial
Natural active immunity results from what?
an individual becoming infected with a disease under normal circumstances, the body produces its own antibodies and continue to for many years.
Artificial active immunity forms what?
the basis of vaccination and involves the inducing an immune response in an individual, without them suffering the symptoms of the disease
What is a vaccination?
The introduction of the appropriate disease antigens into the body, either by injection or by mouth.
What is a vaccine?
something that contains one or more types of antigen from the pathogen
A feature of a successful vaccination programme is that a suitable vaccine must be economically what?
Available in sufficient quantities to immunise most of the vulnerable population.
A feature of a successful vaccination programme is that there must be few side effects from vaccination. Unpleasant side effects may lead to what?
discourage individuals to in he population from being vaccinated.
A feature of a successful vaccination programme is that it must be possible to vaccinate the vast majority of vulnerable population to produce what?
Herd Immunity
A feature of a successful vaccination programme is that staff must be trained, why?
so the vaccine is administered correctly
A feature of a successful vaccination programme is that the vaccines are able to be produced, stored and transported through using what?
Advanced technology
What is herd immunity?
When a sufficient large population of the population has been vaccinated to make it difficult for a pathogen to spread within that population ,usually 85%.
What barriers are there to achieveing herd immunity?
- many don’t want to be vaccinated
- pathogen may mutate and vaccination is seemed to be useless as antignew are not recognised by immune system
To achieve herd immunity, vaccination is best carried out at what time?
one time
What does herd immunity protect?
Those who are ill, have compromised immune systems and young children who are not vaccinated
Why might a vaccine fail?
1) immune system not able to be effective against pathogen
2) infection may have oocured just after vaccination
3) antigens on surface of pathogens may have changed over time due to random mutations
4) some pathogens have many strains at one time with different antigens on their surfaces
5) some pathogens live in not easily accessed locations like instestines
What is HIV?
It is a retro virus, it has RNA as its nucleic acid
What does HIV develop into?
AIDS
What does AIDS stand for?
Acquired immunodeficiany syndrome
On average. How long does it take for HIV to develop into AIDS?
10 years
How can AIDS be treated?
Antiretroviral drugs
What enzyme can be found in a HIV virus?
Reverse transcriptase
What does the enzyme reverse transcriptase do?
Catalyses the formation of DNA from RNA
A HIV virus has a viral envelope which is made up of what?
Lipids derived from cell surface membrane of helper T cells
Glycoproteins are attachment proteins found on the cell surface membrane of a HIV virus, what does it do?
Allows virus to attach to cd4 receptors on the surface of helper T cells
The capsid and the matrix are made up of what in the HIV virus?
Layers of proteins
What is the first key step in a HIV virus entering and replicating in helper T-cells?
HIV enters the blood and the glycoproteins on its surface bind to the CD4 receptors on the surface of the helper T-cell
What is the second key step in a HIV virus entering and replicating in helper T-cells?
The lipid envelope of the virus fuses with the cell surface membrane and the viral RNA and reverse transcriptase enters the cytoplasm of the cell
What is the third key step in a HIV virus entering and replicating in helper T-cells?
Reverse transcriptase catalyses the formation of DNA using Viral RNA
What is the fourth key step in a HIV virus entering and replicating in helper T-cells?
The resulting DNA travels into the nucleus and is inserted into the DNA of the host cell which makes mRNA
What is the 5th key step in a HIV virus entering and replicating in helper T-cells?
mRNA acts as a code for viral proteins to be synthesised at the ribosomes
What is the sixth key step in a HIV virus entering and replicating in helper T-cells?
Viruses are then assembled and leave the cell as they become coated in some of the cell surface membrane of the host cell
What is the last key step in a HIV virus entering and replicating in helper T-cells?
These newly formed viruses are now ready to infect other helper T-cells
How does HIV kill helper T-cells: HIV infection kills helper T-cells, after many years there are too few of these to do what?
Initiate effective immune response
How does HIV kill helper T-cells: T-cells are not stimulated to become cytotoxic T cells or B cells are not what?
Stimulated to become plasma cells
How does HIV kill helper T-cells: A lack of effective immune response means that the secondary infections and cancers like?
HIV
What does ELISA stand for?
Enzyme-linked-immuno-sorbant-assay
Antibiotics only kill what?
Bacteria
There are many different types of _______ that kills many different types of bacteria in many different ways.
Antibody
Why is it difficult to treat viral infections: viruses replicate where?
inside the body cells using the cells own mechanisms and metabolic pathways
Why is it difficult to treat viral infections: it’s difficult for drugs to reach viruses when?
They’re insude body cells
Why is it easier to treat bacterial infections?
You can target the cell walls and attach a drug to 70s ribosomes to stop binary fission
In the ELISA test, what is the 1st step?
A monoclonal antibody is stuck to a well in a plastic container
In the ELISA test, what is the 2nd step?
- Add blood plasma to the well
- HIV antigen in blood plasma binds to the antibody to form an antibody-antigen complex
In the ELISA test, what is the 3rd step?
- A second monoclonal antibody is added to the well to form an antibody-antigen complex with an enzyme bound to it
- Add colourless substrate to the well and observe to look for a colour change as coloured product forms. The colour intensity shows how much HIV is present in the sample
