Cell Recognition And The Immune System

Question 1

What are antigens?

Answer 1

A toxin or other foreign substance which induces an immune response in the body especially the production of antibodies.

Question 2

What is the first stage of phagocytosis?

Answer 2

The phagocyte is attracted to the pathogen by chemoattractants. it moves along a concentration gradient towards the pathogen.

Question 3

What is the second stage of phagocytosis?

Answer 3

The phagocyte binds to the pathogen.

Question 4

What is the third stage of phagocytosis?

Answer 4

Lysosomes within the phagocyte migrate towards the phagosome, formed by engulfing the bacterium.

Question 5

What is the fourth stage of phagocytosis?

Answer 5

Lysosomes release there lytic enzymes into the phagosome, where they break down the bacterium.

Question 6

What is the fifth stage of phagocytosis?

Answer 6

The breakdown products of the bacterium are absorbed by the phagocyte.

Question 7

What is the function of phagocytes?

Answer 7

Engulf any foreign material that has entered the body.

Question 8

What is the first stage of T cells responding to a foreign antigen?

Answer 8

A phagocyte has engulfed a pathogen and displays the antigen on its surface.

Question 9

What is the second stage of T cells responding to a foreign antigen?

Answer 9

The antigen is displayed to many different T cells in the lymph nodes.

Question 10

What is the third stage of T cells responding to a foreign antigen?

Answer 10

clonal selection. Stimulated T cell divides many times (mitosis)

Question 11

What is the fourth stage of T cells responding to a foreign antigen?

Answer 11

Helper T cells secrete chemicals which stimulate phagocytic cells, stimulate B cells to produce antibodies and activate killer T cells.

Question 12

What is the fifth stage of T cells responding to a foreign antigen?

Answer 12

Killer T cells bind to cells presenting the complementary antigen.

Question 13

What is the sixth stage of T cells responding to a foreign antigen?

Answer 13

killer T cells bind to cells presenting the complimentary antigen and kill them.

Question 14

What is the seventh stage of T cells responding to a foreign antigen?

Answer 14

T memory cells formed after infection.

Question 15

Where do T lymphocytes respond to foreign material?

Answer 15

inside body cells

Question 16

Where do T lymphocytes mature?

Answer 16

in Thymus gland

Question 17

Where do B lymphocytes mature?

Answer 17

bone marrow

Question 17

What are T lymphocytes involved in?

Answer 17

cell-mediated immunity

Question 18

What are B lymphocytes involved in?

Answer 18

humoral immunity

Question 19

What do T lymphocytes respond to?

Answer 19

own cells altered by viruses or cancer and to transplanted tissues

Question 20

What do B lymphocytes respond too?

Answer 20

bacteria and viruses , foreign material outside the body.

Question 21

What is the first stage of B lymphocytes responding to a foreign antigen?

Answer 21

cells with the right shape of receptors for antigen is stimulated by T helper cells to divide by mitosis.

Question 22

Once B cells have divided what happens?

Answer 22

B memory cells remain until second infection occurs. Plasma cells secrete antibodies.

Question 23

What do antibodies cause?

Answer 23

Pathogens to clump together. This renders them harmless and prepares them for destruction.

Question 24

How does the structure of antibodies allow them to carry out their function?

Answer 24

Antigen binding site - 3D shape is specific to one type of antigen and allows the antibody to attach due to the complementary shape.
Variable region has a specific sequence of amino acids in the polypeptide chain which causes the shape of the antigen binding site to be specific to complimentary substrate.

Question 25

What are monoclonal antibodies?

Answer 25

Antibodies that are specific to one type of antigen because they are produced from a single plasma cell that has undergone repeated mitosis.