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Immunity Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a pathogen?

A

Any microorganism that can cause disease

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2
Q

Bacteria

A

Prokaryotic cells which can reproduce rapidly by binary fission so a genetic mutation in bacteria can spread quickly and develop resistance.

produce toxins which damage the body

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3
Q

Viruses

A

-Cannot survive or reproduce outside a host cell
-To reproduce they enter a host cells via complementary receptors
-Kill cells by inhibiting them or causing them to burst

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4
Q

Fungi

A

-eukaryotic cells that may be singular/multicellular
-obtain food via secreting enzymes to dissolve substrate then absorb the nutrients
-reproduce by producing spores
-pathogenicity depends on level of penetration

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5
Q

Types of infection

A

Superficial - usually treatable
Sub-cutaneous - treat with antimicrobials
Systematic - usually fatal

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6
Q

How does the body recognise its own cells?

A

Recognises the specific self-antigens surrounded on the cell surface membrane

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7
Q

How do we not produce an immune response to our own cells?

A

In the fetus:
1)lymphocytes constantly collide
2) infection is rare due to sheilding
3) lymphocytes will collide with self-antigens
4) If lymphocytes has receptors that exactly fit the self-antigen then they will die
5) the only remaining lymphocytes are those of which fit to foreign antigens

In bone marrow:
1) Lymphocytes will only initially encounter self-antigens
2) Any lymphocytes that initiate immune response to a self-antigen under apoptosis then differentiate into mature cells
3) No anti-self lymphocytes

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8
Q

What is phagocytes?

A

A type of white blood cell which are produced in the bone marrow before being released into the blood. They are responsible for removing dead cells.

2 main types:
1)Neutrophils
2)Macrophages

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9
Q

Steps for phagocytosis in Neutrophils

A

1) Chemical products of pathogens act as attractions
2) Phagocytes move towards pathogen
3) Phagocyte has receptors on membrane that recognise and attach to antigen on the surface of the pathogen.
4) Engulf the pathogen to form a phagosome
5) lysosomes move towards vesicle and fuse with it
6) enzymes called lysosomes destroy ingested bacteria by hydrolysis of their cell wall
7) Soluble products from pathogen breakdown are absorbed into cytoplasm of phagocyte

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10
Q

Steps of phagocytosis in macrophages

A

Capable of moving into organs as well as blood
-carry out phagocytosis but do not fully destroy pathogens
-cut pathogen and display their antigens on their surface which makes the cell antigen presenting which can then be recognised via lysosomes.

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11
Q

Antigen presenting cell

A

1)Phagocytes which have undergone phagocytosis present pathogens antigens
2)Body cells invaded by virus present some on cell surface
3)Transplanted cells from individuals of same species
4)cancer cells

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12
Q

4 types on t-cells

A

T-helper cells - CD4 receptor which is a specific shape for 1 antigen only

T-effector cells - cells that are produced after t-helper cells have divided they have the same function of t-helper cells

Cytotoxic t-cells- cells will kill infected and nonself cells

memory t-cell- produced when helper t-cells clone and stay in the body to help mount a quicker response of reinfection

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13
Q

t lymphocytes

A

Only respond to APC and each cell has a receptor of which is specific to a single antigen

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14
Q

Cell mediated response

A

1)Pathogen invades the body and antigens are presented on cell surface membrane of a phagocyte

2)Specific receptors on the t-helper cells respond to APC by binding specifically to its antigen

3)Cell is now activated and divides rapidly via mitosis
These cloned cells can develop into:
memory cells
stimulate phagocytes
stimulate b-cells to divide and make antibodies
activate cytotoxic t-cells

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15
Q

What do cytotoxic t-cells do?

A

-They divide via mitosis and kill infected/non-self cells

-Produce proteins called perforin which makes holes in the cell membrane of pathogens so they become permeable and cell dies

-They are most effective against viruses as it prevents them from multiplying

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16
Q

Other than binding to APC what do t-helper cells do?

A

-Secrete cytokines a group of hormones that are activated by t-cells or macrophages
-Include growth factors that initiate cell division.
-Cell toxins to speed destruction
-Interferons to protect cells from further infections
-help activate b cells in humoral response

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17
Q

b-lymphocytes

A

-remain in the bone marrow until matured
-concentrated in lymphnodes and spleen
-each type of b-cell can only make 1 type of antibody and each antibody is specific to one antigen

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18
Q

Humoral Response (primary response)

A

Clonal Selection
1)Pathogen enters the body with unique antigen
2)the b-cell with complementary antibody attaches
3)antigen enters cell via endocytosis
4)antigen is then processed and presented on the cell surface membrane
5) the t-helper cell with complementary receptor binds to processed antigens and stimulates the b-cell to divide (clonal expansion)

cloned plasma cells then produce and secrete antibodies for the pathogen which then destroy the pathogen. Some may become memory cells.

19
Q

Humoral Response (secondary)

A

Plasma cells only survive a few days so memory cells do secondary response:
-if same antigen is encountered again, memory cells will divide rapidly and differentiate into plasma cells which will produce antibodies to kill the cells
-new memory cells will also be made in clonal expansion and will provide long term immunity
-so therefore antibodies are made at much faster rates and concentrations that pathogens are killed before any harm is caused

20
Q

Describe the structure of an antibody

A

-Consists of 4 polypeptide chains 2 light and 2 heavy
-They are joined via dulsulfide bridges
-antibodies variable region includes the specific binding site which is unique for a specific antigen (the sequence of amino acids forming the 3D shape determines this)
-hinge region gives flexibility so binding sites can be placed at different angles.

21
Q

What is agglutination?

A

-due to binging to 2 antigens at a time they can cause the groups of pathogens to clump together .
The clumps make the pathogens less spread throughout the body so phagocytes can more easily locate them and kill them.
The clumps act as markers that stimulate phagocytes to engulf pathogens they are attached too as they are more likely to collide

22
Q

What is a monoclonal antibody?

A

an artificially produced antibody that bind to a specific antigen that activates an immune response

23
Q

How are monoclonal antibodies produced?

A

1) a mouse is vaccinated with the pathogen to begin the production of the antibodies
2) Spleen cells that form antibodies are collected
3) fused with myeloma cells
4) forms a hydridoma
5) grown in a lab an antibodies collected

24
Q

Risks of monoclonal antibodies

A

-deaths whilst trying to treat patients with multiple sclerosis
-clinical trails where severe organ failure occurred

25
Q

Pregnancy Testing

A

If a women is pregnant their urine will contain the protein HCG.

1) Urine is added and will travel up the test strip via capillary action.
2) will bind with antibodies with coloured enzymes and will cause a colour change
3) will continue to move along test strip and reach immobilised antibodies and will bind to these - if this line does not turn blue then the test has not worked

26
Q

The use of therapeutic drugs via monoclonal antibodies

A

-used to treat cancers
-antibodies are produced specific to the cell then given to the patient.
1) attach to receptors on the cell and block chemicals for uncontrolled cancer growth

-indirect antibodies is attaching a radioactive/cytotoxic drug to the antibody to kill the cancer cells

-used to treat breast cancer (hereceptin)

-fewer side effects and cheaper

27
Q

Medical Diagnosis (ELISA TESTING)

A

-to diagnose diseases such as influenza, chlamydia, and cancer
-produce rapid results
1) antigen attached to beaker
2)blood added and antibodies bind
3)secondary antibody with enzyme is added
4)bind to antibodies for the antigen and cause a colour change the deeper the colour the more present the antibodies are in the blood

28
Q

How are monoclonal antibodies useful?

A
  • identical clones of each other
    -highly specific
    -produced in large amounts at a low cost
29
Q

Passive immunity

A

-immune system is not challenged as it does not involve any contact with a pathogen or antigen
-no memory cells are produced so immunity is not long lasting
-occurs when antibodies are passed on from an outside source

Natural- baby to mother across breastmilk or placenta

Artificial- antibodies injected into the body to give immediate protection against life threatening diseases

30
Q

Active immunity

A

-production of antibodies by immune system via direct contact with a pathogen or antigen
-long lasting due to the production of memory cells

Natural- infected via a disease and immune response occurs making antibodies

Artificial - vaccination by inducing immune response without causing symptoms of the disease

31
Q

Vaccines

A

Weakened or dead pathogens or antigens that will produce an immune response causing memory cells to form allowing for faster response during reinfection creating immunity

32
Q

What is a live attenuated vaccine?

A

-weakened whole pathogens
-produces a primary response
-produces strong and long lasting immunity
-unsuitable for those with weakened immune systems

33
Q

What is a inactivated vaccine?

A

-dead whole pathogens or subunits
-cannot cause disease so can use on whose with weakened immune systems
-short weaker immunity
-repeated doses often needed
-allergic reactions
-example is polio and diphtheria

34
Q

Herd Immunity

A
  • when there is a large enough % of the population who are vaccinated against a disease what it becomes difficult for a pathogen to spread
    -important as cannot vaccinate whole population
    -% different for each disease
    -Vaccinations best carried out one by one
35
Q

Why vaccines may not work:

A

-fails to induce immunity e.g defective immune system
-infection occurs straight after vaccine
-antigenic variability
-varieties of one type of pathogen
-pathogen hiding inside cells
-individual objections

36
Q

Success of a vaccine depends on

A

-economic status
-side effects
-production, transportation and storage
-administration
-vaccinate to produce herd immunity

37
Q

Ethical issues of vaccines-

A

-animal testing
-side effects
-testing and trails
-compulsory vaccines
-continuation of expensive programmes
-individual health risks

38
Q

What is HIV-

A

retrovirus that causes AIDS

39
Q

Structure of HIV

A

-attachment proteins
-caspid
-lipid envelope
-RNA
-Reverse transcriptase
-matrix

40
Q

Replication of HIV

A

1)enters the bloodstream
2)attachment protein on surface of HIV binds to CD4 receptor on t-helper cells
3)caspid fuses with cell membrane and RNA enters the t-helper cell
4) reverse transcriptase converts DNA into RNA in the nucleus
5)DNA inserted into the cells DNA
6) mRNA now contains instructions to produce viral proteins
7)protein synthesis occurs and HIV particles are made
8)HIV particles leave the cell with a piece of cell membrane to form the lipid envelope

41
Q

How does HIV cause AIDS

A

-attacks t-helper cells by killing them
200 per cm cubed of blood but should be 800-1200

-without correct amount of t-cells the immune system will not stimulate:

-b-cells to produce antibodies
-cytotoxic t-cells
-memory cells may become infected and destroyed

so therefore the body becomes susceptible to other infections and cancers
symptoms include:
-cancer of brain lungs and eyes
-weight loss
-diarrhoea
It is these secondary diseases that cause death

42
Q

Why antibiotics are ineffective on HIV

A

-work to prevent bacterial cell walls from forming
-cell wall is made of murein and the specific enzymes in the drug will will inhibit other enzymes in the production of cross linkages in cell walls so water enters cell and it lyses

But viruses carry out reactions in host cells and do not have a cell structure so no cell wall of murein. Inside organisms own cells

43
Q

HIV can be transmitted:

A

-sexual intercourse
-blood donation
-sharing of needles used by intravenous drug users
-from mother to child across placenta
-mixing of blood during birth

44
Q
A

Biology (6 decks)

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