paper3 Flashcards
(83 cards)
how do lymphocytes distinguish between slef/ non-self cells`
each cell has specific molecules on its surface w specific shapes these can be used to identify it
how are antigens used in immune response
they are located on surface of pathogen and trigger response from lymphocyte
state non specific immune response
non-specific = phagocytosis
- agglutination of atigens as sntibodues stick them togeather in clumps
- The phagocyte is attracted to the pathogen by non-self ANTIGEN.
- The pathogen is ENGULFED and enclosed in a PHAGOSOME (vesicle).
- LYSOSOMES (made by Golgi) (contain
lysozyme enzymes) fuse with the phagosome. - Lysozymes enzymes hydrolyse molecules and break down the pathogen
(then exocytosis of products)
describe process of antigenic variability
mutation occur in specific gene responsible for the antigen
any previous immunity to pathogen will be lost
describe the barriers blocking pathogens entering the body
skin is a physical barrier that blocks pathogens
stomach acid is a chemical barrier blocking pathogens
white blood cells are the next defence
state the specific immune response
specific = t lymphocyte
the t cells originate i the thymus thats where the t comes from
1) Pathogen enters the body.
2. Phagocyte cells engulf and destroy pathogen and present pathogen’s antigen on their surface.
3. Antigens have a specific tertiary structure. T-cells with a complementary receptor bind. Cytotoxic T cells, kill infected body cells.
4. Helper T-cells stimulate B-cells.
5. B-cells undergo mitosis to clone & make plasma cells.
6. Plasma B cells produce (monoclonal) antibodies.
7. B cells divide (by mitosis) to form Memory B-cells & T-cells divide to form Memory T-cells.
8. More antibodies are produced faster in the secondary immune response. also known as ACTIVE immunity
desc struct of antibody
- Y-shaped
- 2 long polypeptide chains - 2 short polypeptide chains
- constant region
- variable region / antigen-binding site at ends
whats passive immunity
antibodies put into organism
no long term immunity
breast milk
whats active immunity
antibodies created in response to non self antigens
describe how we can target medication to specific cells by the use of antibody.
- monoclonal antibody created that has binding site complementary to that of an antigen on the outside of the cancer cell these are also attcahed to drugs
- cancer drugs are delivered straight to the cell and are killed this is good as it means that there are lesss negative implications when compared to treatments such as chemotherapy and radiotherapy
define vaccine
a dead or inactive form of the pathogen that gets injected into the body
what happens after vaccination
- exposure to antigen activate b cell to differentiate
- b cell undergo mitosis and make large numbers of cells these then differentiate into plasma cells or memory cells
- plasma cells make antibodies
- memory b cells divide rapidly into plasma cells when reinfected by same pathogen these make lots of antibodies rapidly
process of viral replication
- Attachment proteins attach to receptors;
- Viral RNA enters cell;
- Reverse transcriptase makes DNA from RNA;
- The DNA is translated (produces) into viral proteins, capsid & enzymes
- Virus assembled and released from cell
struct of hiv molecule
attachment proteins = on the outside of the molecule
lipid envelope = hold all the stuff
capsid = hold the rna and the reverse transcriptase
how does hiv result in symptoms of aids
virus replicate in the helper t cell this interferes w normal function of immune system
2 uses of monoclonal antibodies
- targeting medication to specific cell types by attaching a therapeutic drug to an antibody
- medical diagnosis.
uses of ant bod for med diag
monoclonala ntibodies could be used to diagnose pregnancy, cancer, covid
describe how we can prevent uncontrolled cell growth of pathogen by the use of antibody.
- monoclonal antibodies binding site complementary to that of an antigen on the outside of the cancer cell
- these attach to cancer cell and prevent chemicals binding that enable the uncontrolled cell division
- these dont damage any other healthy cells only the
describe process of eliza test
1) add antigens to a well and wash multiple times remove any unstuck antigens
2) add complementary antibody forming antigen-antibody complexes wash removing any unbinded antibody molecules
3) Add a second antibody, with an enzyme attached.
and wash
5) Add a colourless substrate which is complementary to & binds to the enzyme’s active site if present. and produce coloured product
investigating translocation
Tracing
- only provide plants with radioactively labeled carbons
- this will be used in photosynthesis to produce sugars
- thin slices of stem placed onto xray film
- this highlights where mass is moving phloem
factors affecting transpiration
light
- the more light the more stomata that are open so more water loss
temperature
- hotter water molecules have more kenetic energy move faster / evaporate faster
humidity
- water potential outside of leaf is greater than inside this results in less evaporation
wind
- maintains the water potential gradient
key features aiding water moving up plant
cohesion tension theory
- cohesion between water molecules / hydrogen bonds makes them stick togeather create contious water column
-adhesion water molecule stick to walls of xylem thinner the xylem the greater the capillary effect
- root pressure as more water move into root the and therefor increase the pressure within the root forces water up the root
formation of tissue fluid
1) capillaries have small gaps called fenestrations
2) as blood enter capilaries from arterioles results in high hydrostatic pressure of the blood
3) water and small molecules are forced out to surroundiing cells this is called ultrafiltration
4) towards venous end hydrostatic pressure has decreased as so much has been forced out pressure within capillary has dropped the water potential has also dropped
5) liquid then re-enter capillary via osmosis
process of water moving up the plant
1) water evaporate out stomata loss in volume create lower pressure (transpiration)
2) as water is lost more water is pulled up xylem to replace it
3) due to hydrogen bond the water creates continous column via cohesion
4) water molecules stick to walls of xylem via adhesion this further helps the movement of water up the plant
