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Flashcards in Mrs Duffy Deck (34):

Name some plasma membrane functions inside and outside the cell.

Outside - separates cell contents , controls transport, cell recognition , cell signalling
Inside- separates organelles , controls transport, surface for reactions , isolates potentially damaging enzymes.


What are glycolipids and glycoproteins?

They allow cells to recognize one and other. Receptors for chems and hormones.


Describe cholesterol

Embedded in the membrane, keeps it mechanically stable and reduces fluidity at Hugh temperatures.


Describe membrane proteins.

Channel- moves charged particles.
Carrier-moves large


Describe diffusion.

No energy needed, molecules move down a concentration gradient.Can move non polars, lipid soluble substances (oxygen) and polar substances as long as there small ( C02), diffusion happens between phospholipids.


Describe facilitated diffusion.

No energy required , moves large and charged molecules with proteins , high to low concentration gradient.


Describe active transport.

Needs ATP, goes against conc gradient from low to high , can move anything but only uses carrier proteins.


Describe osmosis.

No energy needed , uses a water potential gradient from low to high , moves water.


What factors can determine the rate of diffusion?

Steepness of gradient, surface area , the distance over which diffusion occurs, temperature, the type of molecule diffusion, composition and number of proteins.


What happens when a plant cell is placed in distilled water ?

Water enters cell by osmosis down the water potential gradient , cell expands , cell wall stops it from bursting TURGID


What happens when water leaves the vacuole.

FLACCID, if lots of water leave the cytoplasm pulls away from cell wall PLASMOLYSED.


What happens when water enters / leaves an ANIMAL cell.

Enters cell = haemolysed (bursts)
Loses water - crenated


What is the process of active transport ?

1) Cartier proteins take up molecules from outside membrane ( low conc)
2)ATP binds to the protein and splits to ADP+P
3)the binding of the molecule to the protein causes the protein to change its shape so that the molecule can enter the inside of the membrane.
4)the protein no longer binds to the molecules and they are released with the aid of ATP
5)the protein reverts to its binding configuration.


Define and explain co transport.

Ion goes from epithelial cell to blood via AT, co transport of ion and molecule by FD from lumen into the epithelial cell , FD of ions and molecules from epithelial cell into blood.


Describe the non specific defense.

Immediate , physical barriers , phagocytosis.


Name some physical barriers.

Skin, tests , eye lashes , mucus (goblet cells/ciliates cells), HCL in stomach.


Describe the process of phagocytosis.

Bacterium is recognized as foreign so phagocyte is attracted to pathogen by chemotaxis , phagocyte has specific receptors on it CSM which are specific and complementary to the antigens on the pathogen- these bind. The phagocyte engulfs the pathogen , the lysosomes binds to the phagosome and releases lysin which partially hydrolysis the contents, harmless waste products are removed by exocytosis.


Describe the difference between neutrophil and a macrophage.

Neutrophil is multi lobed nucleus and produced in bone marrow, die after phagocytosis
Macrophages are larger and go to are of infection.Dont die after phagocytosis.


Describe the antigens presentation process.

Phagocytosis occurs , then the antigens present in the CSM , the complementary shape of helper cells receptors binds with the helper cell which activated the t Helper cells- which activate B cells (make antibodies ).


What are the 4 steps of the primary immune response.

1) clonal selection
2) T cell activation
3) clonal expansion (mitosis )
4) Differentiation


How do t- cytotoxic cells.

Permeate the cell surface membrane using perforing, allows water to enter and for cell to burst.


What do t helper and t memory cells do?

Helper - secret cytokines (that activate B cells and stimulate phagocytosis)
Memory cells - stay in blood , cut down time for secondary immune response


Describe B cells

Produce in bone marrow , each B cell produces a unique antibody in its surface, B cells also produce plasma cells or memory cells.


Describe how antibodies work/ the process of this.

B cells created the antibodies, the antibodies bind to the pathogens antigens , then agglutination occurs, antibodies bind to the phagocyte receptor and engulfs it all, the lysosomes burns and hydrolysis the pathogen and the phagocyte becomes an antigen presenting cell(presenting the pathogens antigens)


Describe how the structure of an antibody helps fight a pathogen.

Antibodies are made of proteins that have heavy and light chains, constant region (binding site for phagocyte ), variable region (antigen binding site, hinge region (felxibility)


What is a monoclonal antibody ?

It is produced from a single group of genetically identical B cells, they are used for medical diagnosis (pregnancy tests), cancer treatment ( to target cancer cells and deliver a cytotoxic drug )


How do pregnancy tests work?

Antibodies for HCG are bound to a colored bead , when urine is applied, any HCG will bind to the antibody on the beads forming an antigen- antibody complex, urging moves up the stick carrying any beads , the test strip contains antibodies to HCG that are stuck in place , the strip turns coloured if HCG is present because the immobilized antibody binds to the HCG , IF there’s no HCG the beads will pass through the test area without binding to anything.The control zone will bind any antibodies that have not been attached to HCG and shows the test is working.


Describe the structure of HIV

Genetic material in the middle surrounded by capsules and also contains enzyme transcriptase and integrate , taut is all enclosed by a lipid envelope and attachment proteins on the outside that act as antigens.


Explain how HIV infects a t helper cell.

HIV infects T helper by binding to CD4( a receptor ) the genetic material (RNA)travels into the cell. Reverse transcriptase turns RNA into double stranded DNA and is the integrated into the nucleus.Transcription takes place and MRNA leaves the nucleus and attaches to a rib some where HIV proteins are made , the virus rna buds off.


Describe the Elisa test

HIV antibodies bounds to well/wash to remove inbound antibodies / add sample containing HIV antigens / wash to remove inbound antigens /add secondary antibodies with the attached enzyme/wash to remove inbound antibodies/add substrates/colour change =positive result


What are the 4 different types of immunity?

Natural active-contact with pathogen antibodies are made
Artificial active -vaccination with microbe and antibodies are then made
Natural passive -antibodies given via breast milk
Artificial passive-antibodies given through vaccination


How do vaccinations work ?

Vaccine contains antigens , memory cells get made, on secondary exposure memory cells recognize the pathogen , a lot of antibodies are made rapidly and antibodies destroy pathogens.


What’s herd immunity ?

Large number of people vaccinated at the same time and this interrupts transmission in a population so those susceptible never encounter infectious agents .


Why don’t vaccines always work ?

Person could have a defective immune system , antigen variability, different varieties of the pathogen , antigens is concealed.