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a-level biology > chapter 5- cell recognition+ the immune system > Flashcards

chapter 5- cell recognition+ the immune system Flashcards

(48 cards)

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1
Q

what is immunity

A

the ability of an organism to identify and protect itself against foreign molecules and cells

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2
Q

what is an autoimmune disease

A

when the immune system can’t differentiate between self and non-self cells so begins to attack its own cells and tissue

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3
Q

what can the human immune system identify

A

-pathogens
-cells from other organisms of the same species
-abnormal body cells
toxins

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4
Q

what is an antigen

A

small protein molecules on the surface of a pathogen, that are unique to each organism, they trigger an immune response

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5
Q

what are non-specific defense mechanisms

A

defense mechanisms that are immediate and are the same for all pathogens as they don’t distinguish between different types of pathogens

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6
Q

non-specific defense mechanisms examples

A

-skin
-mucus
-ciliated epithelial cells
-HCl in stomach

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7
Q

what are specific defense mechanisms

A

defense mechanisms that are slower and specific to each pathogen as they are able to distinguish between types of pathogen

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8
Q

specific defense mechanisms examples

A
  • white blood cells
    - T lymphocytes + B lymphocytes
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9
Q

what are neutrophils

A

phagocytes that remain in the blood

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10
Q

what are macrophages

A

phagocytes which pass into organs/ tissue

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11
Q

what are the hydrolytic enzymes in phagocytosis

A

lysozymes

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12
Q

what do T lymphocytes carry out

A

cell mediated immunity

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13
Q

what do B lymphocytes carry out

A

humoral immunity

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14
Q

which lymphocytes are involved in the immunity involving body fluids

A

B lymphocytes

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15
Q

which lymphocytes are involved in the immunity involving body cells

A

T lymphocytes

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16
Q

where do T lymphocytes and B lymphocytes form and mature

A

T lymphocytes- form= stem cells in bone marrow
mature= thymus gland
B lymphocytes- form= stem cells in bone marrow
mature= bone marrow

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17
Q

why are T lymphocytes responses known as cell mediated

A

Because T cells can only respond to foreign antigens attached to a body cell

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18
Q

what are the different types of T cells

A

T helper cells
T cytotoxic/ killer cells
T suppressor/ regulatory cells

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19
Q

how does cell mediated immunity take place

A
  • pathogens invade body cells of are taken in by phagocytosis
    -phagocyte place pathogen antigens on its cell surface membranes
    -certain T helper cells have receptors that fit these antigens
    -binding activates the T cell to divide quickly by mitosis and form clones
  • the cloned T cells become memory cells, stimulates B cells to divide, stimulates phagocytosis, activates killer cells to kill infected cells
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20
Q

how do cytotoxic T cells kill infected cells (killer cells)

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A

they produce a protein called perforin which makes holes in the cell surface membrane of infected cells, this causes the cell membrane to become permeable to all substances and die

21
Q

what is humoral immunity

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A

involves B cells which produce antibodies which dissolve in the blood plasma and tissue fluid that can recognize a specific antigen and respond by making a specific antibody to it

22
Q

steps in humoral immunity

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A
  • B cells take up the antigens of pathogens (etc) that enter the blood or tissue fluid
    -B cells process and display the antigen on their cell surface membrane
  • T helper cells attach/bind to the processed antigens on the B cell, this activates the B cell
    -the activated B cells divide b mitosis producing many plasma clones and memory cells
    -the clones plasma cells produce the specific antibody that will exactly fit the antigen on the pathogen
    -the antibody attaches to the antigen on the pathogen and destroys them
23
Q

why at are the two types of clones of B cells

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A

plasma cells
memory cells

24
Q

what are antibodies

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A

Y shaped protein molecules produces by b lymphocytes in response to a specific antigen

25
what is the structure of an antibody
four polypeptide chains, two long/ heavy chains and two short/ light chains linked by disulfide bonds
26
what are the different ways in which antibodies lead to the destruction of cells
- agglutination- clump pathogen together to be engulfed - neutralisation- of toxins produced by bacteria by antitoxins - digestion of bacterial cell membranes - opsonisation- antibody coats the pathogen which identifies it as a foreign cell
27
what are monoclonal antibodies
antibodies which have been isolated and cloned
28
what is direct monoclonal antibody therapy
antibodies which are produces that are specific to antigens on cancer cells , these antibodies are given to patients and attach themselves to the surface of these cancer cells and block the chemical signals that stimulate their uncontrolled growth
29
what is indirect monoclonal antibody therapy
its when a radioactive or cytotoxic drug is attached to the monoclonal antibody. when this antibody attaches to the cancer cells it kills them
30
how do pregnancy tests work
the hormone produced by the placenta, hCG, can be found in the mothers urine. monoclonal antibodies found on an at home pregnancy stick are specific to this and are linked to coloured particles. if hCG is present in the urine it binds to these antibodies. this leads to the hCG-antibody-colour complex traveling along the stick until it is trapped by a different type of antibody creating a coloured line
31
how are monoclonal antibodies made
by the hybridoma method • Mice are injected with an antigen that stimulates the production of antibody-producing plasma cells • Isolated plasma cells from the mice are fused with immortal tumour cells, producing hybridoma cells • The fusion of plasma and tumour cells can be assisted with the use of fusogens such as polyethylene glycol or an electric current • These hybrid cells are grown in a selective growth medium and screened for the production of the desired antibody • They are then cultured to produce large numbers of monoclonal antibodies
32
what is the useful property of plasma cells when producing monoclonal antibodies
plasma cells produce antibodies
33
what is the useful property of tumour cells when producing monoclonal antibodies
tumour cells can divide indefinitely by mitosis and produce more identical cells
34
what is passive immunity
immediate short lasting immunity produced by the introduction of antibodies into individuals from an outside source, without direct contact with the pathogen or its antigens
35
what is active immunity
immunity produced by stimulating the production of antibodies by an individuals own immune system by direct contact with pathogen or its antigens. it is long lasting but takes time to develop
36
what is natural active immunity
an individual becomes infected with a disease under normal circumstances and body produces its own antibodies and may continue to do so for many years
37
what is artificial active immunity
involves inducing an immune response in an individual, without them suffering the symptoms of the disease (vaccination)
38
what is vaccination
the introduction of a dead or inactive version of a pathogen with the appropriate antigens into the body. the antigens stimulate an immune response resulting in the production of memory cells against the specific pathogen/ antigens
39
what is herd immunity
when a sufficiently large proportion of the population has has been vaccinated making it difficult for a pathogen to spread within that population, as it will become very rare for a susceptible individual to come into contact with an infected person
40
what is antigenic variability
when a pathogen mutates causing its antigens to change, causing the pathogen to no longer be recognized by the immune system
41
reasons why vaccinations may not eliminate a disease
- certain pathogens ‘hide’ from the body’s immune system, either by concealing themselves inside cells, or by living in places out of reach (e.g within the intestines) - the pathogen may mutate frequently so that its antigens change suddenly rather than gradually. making the vaccine suddenly ineffective because the new antigens on the pathogen are no longer recognised by the immune system - vaccination fails to induce immunity in certain individuals, for example people with defective immune systems
42
how can HIV virus infect us
-vaginal and rectal sex -drug taking using infected needles -blood infection of wounds - from mother to child across the placenta or via breast milk
43
what is AIDS
a syndrome which occurs as a result of HIV causing the amount of virus to increase whilst the number ion helper T cells decreases leading to the weakening of the immune system and opportunistic infections
44
what is an opportunistic infection
an infection normally controlled in healthy people but potentially life threatening in HIV infected people
45
how does HIV replicate
-the HIV infection enters the bloodstream - HIV attachment proteins binge to the CD4 receptor on helper T cells -the protein capsid fuses with the cell surface membrane -RNA and enzymes of HIV entered helper T cels -HIV reverse transcriptase converts RNA into DNA -DNA is moved into the helper T cells nucleus and inserted into the helper T cells DNA -the HIV DNA in nucleus creates mRNA -the mRNA contains the instructions for making the new viral protein -mRNA passes out the nucleus and uses cell protein synthesis to make HIV particles -HIV particles break away from the helper T cells with a piece of its cell surface membrane which forms their lipid envelope
46
steps in an ELISA test
- an enzyme is attatched to antibodies - when this enzyme reacts with a certain substrate, a coloured products is formed, causing the solution in the reaction vessel to change colour -if a colour change is present, this shows that the antigen or antibody of interest is present in the sample
47
what are the two types of ELISA test
- direct ELISA test- uses a single antibody that is complementary to the antigen being tested for -indirect ELISA test- use two different antibodies (primary and secondary antibodies)
48
why don’t antibiotics work against viral diseases like AIDS?
this is due to viruses lacking the metabolic pathways and structures for the antibiotic to disrupt

a-level biology (6 decks)

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