Cell recognition and immune system - Yr 1

Question 1

Pathogen

Answer 1

A microorganism that causes disease

Question 2

Self

Answer 2

The body’s own cells and molecules.

Question 3

Foreign (non-self)

Answer 3

Not your own body’s cells and molecules.

Question 4

Antigen

Answer 4

A molecule that triggers an immune response by lymphocytes.

Question 5

Lymphocyte

Answer 5

Type of white blood cell responsible for the immune response. They become activated in the presence of antigens. There are two types: B lymphocytes and T lymphocytes.

Question 6

Phagocyte

Answer 6

Type of white blood cell which carries out a non-specific immune response and ingests and breaks down pathogens by phagocytosis.

Question 7

Phagocytosis

Answer 7

Mechanism by which phagocytes engulf particles to form a vesicle or a vacuole.

Question 8

Lysosome

Answer 8

Contain enzymes called lysozymes which they release into the phagosome which hydrolyse the bacterium.

Question 9

Phagosome

Answer 9

A vesicle formed as the bacterium is engulfed by the phagocyte. The lysosome release their lysozymes into the phagosome.

Question 10

Antigen-presentation

Answer 10

When an antigen-presenting cell e.g. phagocyte displays foreign antigens on their own cell-surface membrane.

Question 11

Cell-mediated immunity

Answer 11

The type of response when T lymphocytes respond to antigens that are presented on a body cell.

Question 12

T Cells

Answer 12

Cells which mature in the thymus and are associated with cell-mediated immunity.

Question 13

Clonal Selection

Answer 13

As the receptor on a helper T cell attaches to the antigen this activates the T cell to divide rapidly by mitosis and form a clone of genetically identical cells. These cloned T cells stimulate B cells to divide and form a clone of identical B cells all of which produce the antibody that is specific to the foreign antigen.

Question 14

TH cells (helper T cell)

Answer 14

Contain receptors which respond to a single antigen. Many different types of T cell, each one responds to a different antigen.

Question 15

TC cells (cytotoxic T cells)

Answer 15

Kill abnormal cells and body cells that are infected by pathogens by producing a protein called perforin which makes holes in the cell-surface membrane.

Question 16

Humoral Immunity

Answer 16

The type of response which involves B lymphocytes and antibodies.

Question 17

B Cells

Answer 17

Each type of B cell produces a specific antibody that responds to one specific antigen.

Question 18

Plasma B Cells

Answer 18

When the B cell is activated to divide by mitosis it gives a clone of plasma cells which produce and secrete the specific antibody that exactly fits the antigen on the pathogen’s surface.

Question 19

Antibody

Answer 19

A protein with specific binding sites produced by B cells in response to the presence of appropriate antigen.

Question 20

Memory B Cells

Answer 20

Some B cells develop into memory cells which can respond to future infections by the same pathogen by dividing rapidly and developing into plasma cells that produce antibodies as part of the secondary response.

Question 21

Monoclonal antibodies

Answer 21

Antibodies produced by a single clone of cells.

Question 22

Primary Response

Answer 22

Caused by initial response to the antigen which involves the production of antibodies and memory cells.

Question 23

Secondary response

Answer 23

Caused by second exposure to the antigen. Memory cells are responsible for this response – they divide rapidly and develop into plasma cells (which secrete many antibodies quickly) and more memory cells.

Question 24

Passive immunity

Answer 24

Resistance to disease that is acquired from the introduction of antibodies from another individual, rather than an individual’s own immune system e.g. across the placenta or in the mother’s milk. It is usually short lived.

Question 25

Active immunity

Answer 25

Resistance to disease resulting from the activities of an individual’s own immune system whereby an antigen induces plasma cells to produce antibodies.

Question 26

Natural immunity

Answer 26

A type of active immunity resulting from an individual becoming infected with a disease under normal circumstances.

Question 27

Artificial immunity

Answer 27

A type of active immunity resulting from vaccination. It involves inducing an immune response in an individual without them suffering symptoms of the disease.

Question 28

Vaccination

Answer 28

The introduction of a vaccine containing appropriate disease antigens into the body, by injection or mouth, in order to induce artificial immunity.

Question 29

Herd immunity

Answer 29

Arises when a sufficiently large proportion of the population has been vaccinated which makes it difficult for a pathogen to spread within that population.

Question 30

Antigenic variability

Answer 30

Pathogen may mutate frequently so that its antigens change suddenly rather than gradually which means vaccines become ineffective because the new antigens on the pathogen are no longer recognized by the immune system.

Question 31

HIV

Answer 31

Human immunodeficiency virus which causes the disease acquired immune deficiency syndrome (AIDS). It has a lipid envelope, attachment proteins, a capsid and two single strands or RNA and enzymes.

Question 32

Reverse transcriptase

Answer 32

An enzyme in HIV which enables the production of DNA from RNA.

Question 33

Retrovirus

Answer 33

A group of viruses which have the ability to make DNA from RNA because they have reverse transcriptase.

Question 34

mRNA

Answer 34

A single stranded polynucleotide found in HIV.

Question 35

AIDS

Answer 35

The disease caused by HIV.

Question 36

ELISA test

Answer 36

Enzyme linked immunosorbent assay which uses antibodies to detect the presence and quantity of a protein in a sample.

Question 37

Antibiotic

Answer 37

A substance produced by living organisms that can destroy or inhibit the growth of microorganisms