Section 2:Cell recognition and Immune system

Question 1

Define antibody

Answer 1

A protein produced by lymphocytes in response to an appropriate antigen

Question 2

Define lymphocyte

Answer 2

White blood cells involved in immunity

Question 4

Define phagocytes

Answer 4

White blood cells that engulf and digest any microbes and waste materials they find

Question 5

Define pathogen

Answer 5

A microorganism that causes a disease

Question 6

What are the two parts of the immune systems and what are the types in each part?

Answer 6

• Non-specific response ~ Physical barriers and phagocytosis
• Specific response~Cell mediated response and Humoral response

Question 7

What’s the difference between cell mediated response and humoral response?

Answer 7

Cell mediated response is T lymphocytes and Humoral response is B lymphocytes

Question 8

Three points

Give examples of physical barriers of the immune system

Answer 8

• Mucus and cilia prevent the entry of pathogens into the lungs
• Blood clotting seals wounds
• Acid in the stomach kills any bacteria that enter with food

Question 9

Why are physical barriers a non-specific response?

Answer 9

They do no distinguish between one pathogen and another. All pathogens are treated in the same way

Question 10

What are the two types of antigens and define them?

Answer 10

Self and non-self
Self antigens are recognised tag on the surface of cells that does not cause an immune response
Non-self antigens are foreigns tags on the surface of cells that activates an immune response
Made of proteins

Question 11

Give examples white blood cells

Answer 11

Phagocytes and lymphocytes

Question 12

Six points

Describe the process of phagocytosis

Answer 12

1. Chemical products of pathogen attracts phagocyte move towards pathogen
2. Phagocytes have receptors attach to chemicals on the surface of the pathogen
3. Phagocytes engulf pathogen and form a phagosome
4. Lysosomes move towards the phagosome and fuse with it
5. Lysoszymes within lysosomes break down the pathogen
6. Soluble products are absorbed into the cytoplasm

Question 13

Why are people given immunosuppressant drugs after an organ transplant?

Answer 13

To stop the body from developing antibodies to the new kidney as it will recognise if the antigens are non-self

Question 14

Where do the different types of lymphocytes mature?

Answer 14

B lymphocytes mature in the bone marrow
T lympocytes mature in the thymus gland

Question 15

Why is antigen presentation important?

Answer 15

Allows T helper cells and the immune system to recognise the invader/pathogen and become activated

Question 16

Describe the process of antigen presentation

Answer 16

1. Phagocytes ingest a pathogen
2. Removes the antigen from the surface of the pathogen
3. Then places antigens on its own cell membrane

Question 17

What happens after antigen presentation occurs?

Answer 17

Receptors on a specific helper T cell fit exactly with the antigens on the phagocytes
This activates the T cells to divide rapidly by mitosis and form a T cell clone

Question 18

What can cloned T cells do?

Answer 18

• Develop into memory cells
• Stimulate phagocytes
• Stimulate B cells
• Activate cytotoxic T cells

Question 19

What do cytotoxic T cells do?

Answer 19

• Produces perforin,protein,that makes holes in the cell-surface membrane
• Cell membrane becomes freely permable to all substances and the cell dies as a result

Question 19

T lmphocytes

Describe the process of a cell mediated response

Answer 19

1. Pathogen invades body cell or is engulfed by phagocyte
2. Phagocyte becomes antigen presenting cell
3. Specific receptors on cell surface of T helper cell binds to antigens on surface of phagocyte~this activates other T cells to divide by mitosis to form clones
4. The activated cloned T cell can develop into a memory cell (secondary immune response)
5. The activated clone T cell can develop can phagocytes to engulf pathogens by phagocytosis
6. The cloned T cells can stimulate cytotoxic T cells

Question 20

What does humoral immunity involve?

Answer 20

Production of antibodies in bodily fluids

Question 21

Describe the process of humoral immunity

Answer 21

1. Pathogen is engulfed by a B cell (B lymphocyte) and B cell becomes antigen presenting cell
2. B cell posses the antigen posseses the antigen and the coressponding T helper cell activates the B lymphocyte
3. B cells are activated and divide by mitosis to produce clones of plasma cells
   4.

Question 22

What are the two types of cell a b lymphocyte can develop into and describe its function

Answer 22

• Plasma cells=produce antibodies which leads to the destruction of an antigen
• Memory cells=Doesn’t produce antibodies but circulates in the blood and tissues. When they encounter and antigen at a later date they divide rapid rapidly to produce plasma cells and memory cells

Question 23

What is the definition of an antibody?

Answer 23

• Are protein that has a specific antigen binding site where the antigen on the bacteria binds to, forming an antigen-antibody complex

Question 24

What are two features of an antibody?

Answer 24

• Antibodies are proteins
• They are specific to an antigen

Question 25

Describe the structure of an antibody

Answer 25

• Two heavy chains and two light chains
• A receptor binding site
• An antigen binding side
• A variable region
• A constant region

Question 26

What is a variable region on an antibody?

Answer 26

Each antibody has a different variable region shape due to amino acid sequence that is complementray to a specific antigen

Question 27

What bands hold together the different polypeptide chains in an antibody?

Answer 27

Disulfide Bridges

Question 28

What are the two different types of antibody responses and give a basic description