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Bio Aqa > Cell Recognition And Immune System > Flashcards

Cell Recognition And Immune System Flashcards

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Biology 101 flashcards
1
Q

What are lymphocytes

A

A type of wbc that recognise foreign material

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2
Q

How do they recognise and whag else can they do

A

Due receptors on their cell surface
They can also bind to other cells and molecules in the body

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3
Q

What does each receptor have

A

Spec seq of amino acids = specific 3D shape so they only bind to one specific molecule

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4
Q

Why are protiens highly variable

A

Differences in dna

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5
Q

What is recognised as foreign

A

Allergens (eg pollen - hay fever)
Cancer cells
Cells from other species/ members of same species - eg organ transplant
Pathogens
Toxins

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6
Q

Define cell recognition

A

How body cells communicate to recognise eachother and foreign material in body

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7
Q

Why is a virus not a true organism

A

Cannot replicate alone - needs to invade a host cell to reproduce

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8
Q

Antigen definition ( 2 marks)

A

A specific protein on the surface of a pathogen that causes an immune response.

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9
Q

What is the immune system

A

Large network of organs, wbc, protiens (antibodies)

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10
Q

Some bodily defense systems

A

Mucous mem
Bone marrow
Thymus
Spleen

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11
Q

Whag are 2 responses out body cells have to defend against disease

A

Non specific and specific

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12
Q

Non specific and what it’s broken down into

A

Physical and chemical Barriers
Phagocytes

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13
Q

specific and what it’s broken down into

A

Cell mediated response
Humoral response (b cells)

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14
Q

differences between them

A

1) Non specific is an immediate response whilst specific has a slowed

2) non specific has the same response no matter what type of pathogen whilst specific has a specific response depending on pathogen

3) in non specific memory cells aren’t formed whilst in specific memory cells are formed

4) non specific uses phagocytes whilst specific uses lymphocytes

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15
Q

Similarities

A

Both systems recognise and respond to foreign material

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16
Q

Why does specific have a lag time

A

Bc of time bet infection and destruction of pathogen .. takes time for wbc w complementary receptors to attract to pathogen

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17
Q

2 physical Barriers

A

Skin
Epithelial mem
Scab formation (platelets)

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18
Q

Skin

A

Thick water proof impermeable layer to path

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19
Q

Epithelial mem

A

In trachea and bronchi
There are ciliated epithelial cells … cilia waft pathogen
Some cells create sticky mucus which traps pathogens

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20
Q

Chemical Barriers

A

Tears
Stomach acid
Skin secretions

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21
Q

Tears

A

Enzymes in tears (lysozymes) which hydrolyse pathogens

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22
Q

Stomach acid

A

HCL - low ph of 1 - pathogens cannot survive

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23
Q

Skin sections

A

Oil and sebum which lowers ph of skin pathogens cannot survive

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24
Q

How is foetus protected from pathogens

A

Placenta protects from infection
Lymphocytes which collide with exclusively self material - could attack own tissues
Lymphocytes that show immune response to self cells are suppressed/inactivated

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25
Q

Whag is the term given to the process of lymphocytes being suppressed/inactivated due to showing immune response to self cells

A

Apoptosis

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26
Q

Phagocytosis

A

Process whereby phag in blood engulf pathogens

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27
Q

How is phag specialised

A

Contains lysosomes - release hydrolytic enzymes (lysozymes) to break down unwanted cells

Lobed nucleus (not circ) allows cells to be flexible and move freely around pathogens

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28
Q

1st step of phagocytosis

A

Phag attracted to path due to trail of chem products left by path

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29
Q

2nd

A

Phag attaches path
Receptors on phag bind to antigen on path

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30
Q

3rd

A

Phag Engulfs path takes into vehicle phagosome

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31
Q

4th

A

Lysosomes move toward phagosome leaving lysozymes

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32
Q

5th

A

Lysozymes (digestive enzymes) destroy (hydrolyse) path
Into debris
This is absorbed and used by cell

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33
Q

Components of phospholipid mem

A

Phospholipid
Cholesterol
Glycolipid
Glycoprotein
Intrinsic protien
Extrinsic protien

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34
Q

Phospholipid

A

Hydrophobic head
Hydrophilic tail which face inwards
Forms bilayer due to polarity
Don’t allow large molecules polar or lipid sol mol to pass
Eg ions
So it’s a barrier to those sub

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35
Q

Cholesterol

A

Cholesterol = stability
Lipid that binds to hydrophobic tails and pulls them together
Restricts movement
Mem less fluid and more rigid

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36
Q

Intrinsic proteins

A

Include carrier and channel protiens
Allow for large mol and ions to pass through mem

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37
Q

Glycolipid

A

phospholipid attached to polysaccharide

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38
Q

Glycoprotein

A

Protein attached to polysaccharide chains

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39
Q

What do extrinsic protiens, glycolipids and glycoproteins do

A

All act as receptors
They bind to other cells (communication)
And foreign cells (pathogens)
They bind to and detect chem released from cells eg toxins hormones

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40
Q

receptor function

A

specific mol on a cells surface (usually proteins) that enable immune system to identify
pathogens
cells from other organisms of the same species
abnormal body cells
toxins

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41
Q

what do antigens identify

A

pathogens

42
Q

why are some bacteria and viruses able to survive

A

their antigens mutate

43
Q

what is antigen variability

A

since antigens on bacteria and viruses can mutate (change dna seq) the immune system cannot detect newly mutated antigens

44
Q

2 types of lymphocytes

A

b cells
t cells

45
Q

where are t cells found and function

A

mature in thymus gland
involved in cell mediated response

46
Q

where are b cells found and function

A

mature in bone marrow
involved in humoral response

47
Q

what defense system is the cell mediated and humoral response in

A

specific

48
Q

immunity def

A

ability of organisms to resist infection by protecting agianst disease causing pathogens and toxins

49
Q

cell mediated response - what t cells only respond to

A

antigens on bodies cells

50
Q

what kind of body cells are they

A

infected cells
cells from other organsims or species
cancerous cells

51
Q

last step of phagcytosis

A

once phag has englulfed and hydrolysed path
it presents a small part of a path ( eg protien) on its cell surface mem

52
Q

what is cell now known as

A

antigen presenting cell
APC

53
Q

next step of cell mediated response

A

t cells come that has a receptor specific to antigen on APC

54
Q

types of t cell

A

t helper cell
cytotoxic t cells

55
Q

t helper cell (Th) func

A

involved in cell recognition
stimulates other processes in immune system
cell communication in response to abnormal or infected cells

56
Q

cytotoxic t cell (Tc func

A

kills infected/abnormal cells by producing protein perforin that makes holes in cell surface membrane making it freely permeable so infected/abnormal cell dies

57
Q

step 1 of Th rec

A

phag engulfs and hydrolyses path

58
Q

step2

A

phag presents antigen on cell surface mem becoming apc

59
Q

step 3

A

specifc t helper cell with comp receptor binds to presented antigen

60
Q

step 4

A

this activates Th it undergoes mitosis to form many identical copies of itself

61
Q

what is it called when Th undergoes mitosis

A

clonal selection

62
Q

4 things tht cloned t helper cells become

A

memory cells
stimulate phagcytosis
stim division of b cells -humoral response
become cytotoxic t cells

63
Q
  1. Describe how T lymphocytes recognise and destroy pathogens. (3 marks)​
    ​
  2. State what chemical cytotoxic T-cells release and describe what this chemical does. (2 marks)​
A
  1. Has a receptor that binds to antigen on antigen presenting cell. Divides by mitosis to form many clones. Some differentiate into cytotoxic T cells which destroy infected cells. (Also stimulates production of B cells, phagocytosis and differentiation into memory t cells
  2. Perforin, makes holes in the cell-surface membrane of infected cell. Makes it freely permeable, so it dies.​
    ​
64
Q

what response is b cells involved in

A

humoral response

65
Q

where do b cells mature

A

mature in the bone marrow

66
Q

antibody key definition

A

an antibody is a specific protein secreted by a plasma cell ​

67
Q

2 types of b cells

A

plasma cell
memory cell

68
Q

what do both types of b cells have

A

Both types have receptors, which are membrane-bound antibodies.​

69
Q

components of antibody

A

2 heavy chains
2 light chains
receptor binding site
antigen binding site x2
variable reigon
constant reigon

70
Q

what order of stuc does antibody have

A

quaternary

71
Q

why does antbody have quaternary struc

A

made up of more than one polypep chain
4 chains

72
Q

what is variable reigon of antibody

A

specifci 3d shape - tertiary
det by primary struc
specifc to each antibody

73
Q

what holds heavy chains together

A

2 disulfide bonds

74
Q

what holds heavy and light chain together

A

1 disulfide bond

75
Q

where is receptor binding and antigen bindng site found

A

antigen bindig at top
receptor binding at bottom

76
Q

receptor binding site for what kinf of cell

A

b cells

77
Q

how many antigen bindinfg sites are in antibody

A

2

78
Q

what is constant reigon

A

same seq of amino acid

79
Q

define endocytosis

A

process of bringing substances into cell where vesicle forms around digested material

80
Q

1st step of humoral res

A

invading path has antigen on cell surface mem that is comp to receptor on b cell

81
Q

2nd step of humoral res

A

pathogen enters b cell via endocytosis, the b cell becomes apc - presents an antigen on its cell surface mem

82
Q

3 rd step of humoral

A

Th (t helper) cell binds to presented antigen

83
Q

4th step of humoral

A

t - h binding stim b cells to undergo clonal selection by mitosis

84
Q

5th step of humor

A

in each clone of b cells
they differentiate into either plasma cell or memory cell

85
Q

6th step of hum

A

antibodies prod by plasma cell attach to antigen on path lesding to destruction
antibodies act as markers phagocytes and clump multiple cells togther (aggultintion)

86
Q

plasma cell func

A

involved in primary res by secreting antibodies
which attach on antigen on path to digest and hydrolyse
secreted antibodies also act as markers phagocytes and clump multiple cells togther (aggultintion)

87
Q

memory cell func

A

circ in blood waiting for rexposure so involved in secondary immune res

88
Q

monoclonal antibodies shortened into …

A

mAb’s

89
Q

mAb’s def

A

antibodies w same tertiary struc prod from single clone of b cells

90
Q

uses of mAb’s

A

cancer treatments
preg tests
elisa test - detect antigens or antibodies in blood - so testing for disease

91
Q

describe 2 types of cancer treatments

A

theraputic drug attached to anibody targetinf medication to specific cell types (cancer cells)
chemo - involves fusion of drugs that target dividing cells - also includes cells in hair follicles along w cancer cells so cause hair loss and weight loss

92
Q

how do we use mAb’s agaiasnt cancer cells

A

cancerous cells display diff antigens to normal body cells so we make mabs target these

93
Q

advantage of mabs in cancer therapy

A

less side effecsts then w chemo bc they target cancer cells w out destroying healhy body cells

94
Q

disadvantages of mabs in cancer thearpy

A

allergic reac are common
doesnt work on all cancer cell types
we dont know long term effects
most mabs in clinical trial stage
some mabs have side effects related to antigens they target

95
Q

what do 2 lines in preg test show

A

positive res

96
Q

what does 1 line in preg test show

A

neg res

97
Q

what does urine of a preg lady conain

A

hcg hormone

98
Q

how does preg test work

A

1) sample pad absorbs urine
2) urine travles up reaction zone which contains mobile abs comp to hcg
3) travel up stick in result window
which contain immobilsed abs also comp to hcg
4) mobile abs continue moving up control window this contains immobilsed abs comp to mobile abs from reaction zone

99
Q

what does elisa test do

A

use mbs to detect presense and quant of proteins in blood plasma
these proteins are antibodies or antigens

100
Q

elisa test steps in detecting antigens in blood

A

1) apply blood serum to well plate with antibodies attached o it
2)wash to remove unbound antigens
3) add 2nd enzyme linked to antibody which binds to 1st antibody so is comp
4) wash to remove excess enzyme linked antibody
5) colourless substrate added which binds to enzyme on antibody
6) for positive test res colour change observed

101
Q

why is it important that plate is washed again after 2nd enzyme linked antibody is added

A

washed out again to remove any unbound secondary antibodies. This is a very important step in avoiding false-positive test results.

102
Q

how does elisa test work for detecting antibodies

A

antigens are attached to well

Bio Aqa (7 decks)

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