topic 2 c Flashcards
what are antigens
molecules that generate an immune response when detected by the body
where antigens usally found
on the surface of cells and are used by the immune system to identify pathogens, abnormal body cells and toxins
how many stages of the immune system are their
4
what is a phagocyte
a type of white blood cell that carries out phagocytosis found in blood and tissue
how do phagocytes work
1) the phagcyte recognises the foreign antigen
2) the cytoplasm of the phagocytes moves round engulfing it
3) the pathogen contained in the phagocytic vacuole in the phagocytes
4) a lysome produces hydrolytic enzymes that break down the pathogen
5) the phagocytes then presents the antigen on it surface to activate an immune response
what is a t-cell(t-lymphocyte
another type of white blood cell. it has receptor proteins on it surface complimentary to the antigens on phagocytes
how does a t-cell respond to a complimentary antigen
this activates the t-cell
their are different types
t-helper cells release chemical signals that stimulate a phagocytes
cytotoxic t-cells kill abnormal and foreign cells
what is the job of a b-cell
it binds to a complimentary shaped antigen
together with the substance released from thelper it activates the b-cell
this activates the b-cell to divide onto plasma cells
what is aggulation
when pathogens get clumped together by plasma to help speed up engulfing by phagocytes
what is a cellular response
the t-cells and other immune system cells that they interact with
what is a humoral response
b-cells, clonal selection and production of monoclonal antibodies
what is primary immune response
1) when an antigen enters the body for the first time it activates the immune system
2) this is usually a slow response because their isn’t to many b-cells
3) after being exposed for the first time the b-cells and t-cells produce memory cells which remain in the body for a long time
making the person immune
what is the secondary immune response
-if same pathogen enters body the response is much quicker and stronger
-clonal selection happens a lot faster
-usually gets rid of pathogens before you even notice
how do vaccines work
you get injected with a weakened or dead version of the pathogens then your body produces an immune response which inturn creates memory cells this reduces the chance of illness
how can vaccines be taken
orally or injected
how does antigenic variation help some pathogens evade immune system
they do this by changing the surface antigens shape so the antibodies are not complimentary so they have to produce a immune response to create a new one which takes more time so it can make you ill
what is active immunity
this is the type of immunity when your immune system makes its own antibodies
what are the 2 types of active immunity
natural- when you become immune after catching it
artifical- when you have been vaccinated
what is passive immunity
when you are given antibodies made by another organims
what are the 2 types of passive immunity
natural- when it happen when a baby gets it from their mum
artificial- when it is injected
compare active and passive immunity
active- require exposure to antigen
takes a while
memory cells produced
protection is long term
passive - doesn’t need exposure
protection is immediate
memory cells arent produced
short term protection
what are monoclonal antibodies
antibodies produced from a single group of genetically identified b-cells
they are very specific because of their tertiary structure
what can monoclonal antibodies be used for
cancer treatment
finding diseases
prenancy tests
what is the elisa test
a monoclonal test used for medical diagnosis
what is the direct elisa
uses a single antibody
what is an indirect elisa
uses 2 different antibodies
how do you carry out the elisa test
An enzyme is attached to antibodies
When this enzyme reacts with a certain substrate, a coloured product is formed, causing the solution in the reaction vessel to change colour
If a colour change occurs, this shows that the antigen or antibody of interest is present in the sample being tested (e.g. blood plasma)
why do you have to rinse the dish after every step
to make sure their is no antibodys that could effect the test that are not bound
what are some ethical issues surrounding vaccines
-tested on animals
-testing on humans can be tricky
-some people don’t want to take the vaccine because of side effects
- lots of new diseases so cant develop quick enough
what is HIV
Human Immunodeficiency virus- that affects the immune system and leads to AIDS which is a condition where the immune system deteriorates and eventually fails
what cells does does HIV infect
the helper T-cells which acts as a host cell this means that the body immune response is affected as these are a big part of the process
what is the structure of a HIV
spherical
it contains attachment proteins, capsid, gentic material, reverse transcriptase and an envelope
what is the job of reverse transcriptase
used for replication
how does HIV replicate
The virus uses the cell machinery of helper T-cells to multiply:
Viral RNA enters the cell
Viral reverse transcriptase enzymes produce a DNA copy of the viral RNA
The DNA copy is inserted into the chromosomes of the cell
Each time the cell divides it copies the viral DNA
The infected cells remain normal as the viral DNA is inactive
when are people classed as having AIDS
when their helper tcells count drops below a certain level
what are the symptons of aids
infections of the mucus membrane and recurring respiratory infections
the immune system becomes more inactive so more diseases attack you
is their a cure and why
No as it is a virus and they are hard to treat as they are inside the cells. but antiviral drugs can slow down the effects of it
how does it spread
unprotected sex and sharing needles
