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Biology > [Unit 2.4] Cell Recognition and Immune System > Flashcards

[Unit 2.4] Cell Recognition and Immune System Flashcards

Cells (65 cards)

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1
Q

what defences do humans have against pathogens

A

skin
mucus
stomach acid
immune system

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2
Q

what is a self cell

A

a cell of our own body

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3
Q

what is a non-self cell

A

a cell of a different organism

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4
Q

what must the immune system be able to recognise

A

pathogens
abnormal cells (cancer/old cells)
toxins
cells from other organisms (same species)

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5
Q

describe the process of phagocytosis

A

-Phagocyte attracted to pathogen by chemical products. Moves along conc. gradient
-Phagocyte has receptors that bind to chemicals
-Lysosomes migrate to phagosome
-Releases lysozymes that hydrolyse pathogen
-Products are absorbed by phagocyte
-Antigens from pathogen put on membrane

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6
Q

define specific immune responses

A

slower, specific to each pathogen, longer lasting

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7
Q

define non specific immune responses

A

immediate, same for all pathogens

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8
Q

examples of specific immune responses

A

cell mediated response, humoral response

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9
Q

examples of non specific immune responses

A

physical barrier, phagocytosis

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10
Q

how do cytotoxic T cells work

A

they bind to infected cell
perforin makes holes in membrane
infected cell lyses

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11
Q

what is the role of cytotoxic T cells

A

to kill abnormal cells / cells infected

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12
Q

what do helper T cells do

A

activate B cells
activate cytotoxic T cells
increase rate of phagocytosis

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13
Q

how are T lymphocytes activated

A

they cannot recognise foreign antigens directly
only respond when presented by antigen presenting cells (phagocytes, macrophage)

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14
Q

how does cell mediated immunity work/ what is the process

A

-Phagocyte places antigens on membrane
-Antigens fit into immature T cells receptors
-T cells divide rapidly by mitosis and form:
– memory cells
– helper T cells
– cytotoxic T cells

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15
Q

define “humoral”

A

immune response that involves B cells producing antibodies that circulate in the blood

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16
Q

what is clonal selection

A

B cells complimentary receptor binds to antigen of pathogen activating it
OR
Helper T cell activates

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17
Q

what is clonal expansion

A

B cell undergoes mitosis
most turn into plasma cells
some into memory B cells

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18
Q

what do plasma (B) cells do

A

make antibodies that bind to pathogens antigen

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19
Q

how do long living memory B-cells work

A

immunological memory
if same pathogen detected again, they divide quicker and create plasma cells.

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20
Q

What is the basic structure of an antibody?

A

An antibody is composed of four polypeptide chains: two heavy chains and two light chains, forming a Y-shaped molecule.

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21
Q

what is the region of the antibody that binds to the antigen called

A

variable region/antigen binding site

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22
Q

What role does the constant region of an antibody play?

A

The constant region determines the class of the antibody and mediates interactions with other immune cells.

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23
Q

What type of bonds contribute to the stability of the antibody structure?

A

Disulphide bridges

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24
Q

Describe the function/role of antibodies in the immune response.

A

Antibodies identify and neutralize foreign objects like bacteria and viruses.

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25
do antibodies directly kill pathogens.
no
26
What is the significance of the hinge region in antibodies?
The hinge region allows flexibility, enabling the antibody to bind effectively to antigens.
27
what part of the antigen does the variable region bind to
epitope
28
what makes the variable region unique to each antibody
specific sequence of amino acids
29
what is it called when the antigen binds to the antigen binding site
antigen-antibody complex
30
what are the four ways antibodies fight pathogens
agglutination neutralisation complement cascade coat viruses/bacteria
31
define "agglutination". what diseases does it help against
antibodies cause pathogens to stick together. easier for phagocytes to engulf and destroy most pathogens
32
define "neutralisation" what diseases does it help against
neutralises toxins produced by pathogens bacterial infections
33
define "complement cascade" what diseases does it help against
antibodies create holes in bacterium by reacting with blood proteins. cell bursts. bacterial infections
34
define "coat viruses / bacteria" what diseases does it help against
antibodies bind to attachment proteins. prevents virus entering cell. easier for phagocytes to engulf bacterial or viral diseases
35
define "monoclonal antibodies"
antibody produced from a single group of genetically identical B cells.
36
define "direct therapy" in terms of monoclonal antibodies
MA is specific to cancer antigens. they can target and bind to cancer cells. blocking chemical signals that are telling it to rapidly divide
37
define "indirect therapy" in terms of monoclonal antibodies
cytotoxic drugs binds to MA. MA binds to antigen on targeted cell. Cytotoxic drug destroys the cell.
38
how are monoclonal antibodies used in diagnosis
antibodies target antigens to measure level of that antigen in the body.
39
what are the side effects of monoclonal antibodies
vomiting, fever , low blood pressure
40
what are the ethical issues with monoclonal antibodies
requires animal testing: immune cells harvested from mice
41
what does ELISA stand for
enzyme linked immunosorbent assay
42
define "immunosorbent"
technique of using antibodies absorption property to test for antigens
43
what are the uses of ELISA
diagnosis research purposes detecting proteins, hormones etc (qualitative) how much antigen present (quantitative)
44
define "direct ELISA"
using one type of antibody
45
define "indirect ELISA"
using two different types of antibodies
46
how does direct ELISA work
add antibody with enzyme added to well antibodies will bind to antigens wash unbound antigens with buffered salt solution add substrate coloured product will form
47
what is the purpose of indirect ELISA
to detect small amounts of antigens increasing sensitivity of colour change
48
how does indirect ELISA work
antibody complementary to antigen added to well (primary) antibody with enzyme added to well (secondary) antibody with enzyme binds to each other and primary antibody. (stack) unbound antibodies washed with buffered salt solution add substrate coloured product will form
49
what is active specific immunity
making your own antibodies when exposed to antigen
50
what is passive specific immunity
given someone else's antibodies
51
what is natural active specific immunity
antigen enters body naturally. body produces antibodies
52
what is natural passive specific immunity
antibodies passed from mother to foetus/new-born through placenta/milk
53
what is artificial active specific immunity
antigens in vaccine introduced to body. antibodies formed
54
what is artificial passive specific immunity
preformed antibodies injected into body in a serum.
55
define "herd immunity"
when social circle is vaccinated. even if you're susceptible, you wont catch disease as there isn't anyone to give it to you
56
how do vaccines work
giving someone a weakened or dead pathogen or isolated antigen from pathogen.
57
difference between active and passive specific immunity
active: -exposure to antigen -protection is long term -takes a while for protection to develop -memory cells produced passive: -no exposure to antigen -protection is short term -immediate protection -no memory cells produed
58
what are the ethical arguments FOR vaccines
-saves lives -prevents spreading of disease -reduces suffering -cheaper to protect than recover -herd immunity
59
what are the ethical arguments AGAINST vaccines
-animal testing -side effects -freedom of choice for mandated vaccines -who gets vaccine first? -risk to human volunteers at clinical testing
60
define "antigenic variation"
antigens on virus change due to mutation. new strains of virus emerge
61
what is the role of reverse transcriptase
replicating the virus. converting RNA to DNA
62
describe the process of HIV replication
-attachment proteins attach to receptor on helper T cell -capsid released and uncoats itself. releasing RNA and reverse transcriptase -reverse transcriptase used to make complementary strand of DNA -reverse transcriptase turns single stranded DNA into double stranded DNA -DNA is inserted into host's genome in nucleus -host's enzymes & ribosomes used to make viral proteins -host's enzymes make RNA genome copies for new virions -these infect other helper T cells
63
what does AIDS stand for
acquired immune deficiency syndrome
64
what are the symptoms and development of AIDS
initially flu-like symptoms then latency period (virus is dormant) low helper T cell count in blood can take 10 years to develop into AIDS get sick with diseases most people immune to infections become more frequent and more life threatening death is caused by other pathogens or cancer
65
what determines how long HIV will take to develop into AIDS
strain of HIV, age, genetics

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