Cells - Immunity

Question 1

What are the 2 types of immune systems?

Answer 1

Specific

Non-specific

Question 2

Define the non-specific immune response

Answer 2

The response that doesn’t take into account the pathogen

Barriers to infection

Phagocytosis

Question 3

What are 3 non-specific barriers to infection?

Answer 3

• > skin prevents pathogens entering the body
• > hydrochloric acid in the stomach denatures enzymes / protein coat of most pathogens
• > epithelial layers produce mucus that pathogens stick to and become immobolised

Question 4

Define phagocytosis

Answer 4

When phagocytes engulf and break down pathogens

Question 5

what is the process of phagocytosis?

Answer 5

phagocyte detects and moves towards chemicals released from pathogen along a conc gradient

receptors on phagocytes attach to chemicals on surface of pathogen

phagocyte engulfs pathogen into a vesicle

vesicle carries pathogen to phagosome + fuses, releasing pathogen

lysosomes fuse with pathogen and hydrolyse with lysozymes

products absorbed by phagocyte

Question 6

Define an antigen

Answer 6

Any part of an organism (often proteins found on the surface of a cell) that is recognised as foreign by our immune system

Question 7

What are T-Lymphocytes also known as?

Answer 7

T-Cells

Question 8

What are the 2 forms of T-Cells?

Answer 8

helper T-Cells (T_H Cells)

cytotoxic T-Cells (T_C Cells)

Question 9

which process are T-Cells involved in?

Answer 9

cell-mediated

Question 10

Describe what happens to the antigens during phagocytosis

Answer 10

when pathogen is destroyed, phagocyte presents the antigen on their outer membrane for T-Cells to bond to

phagocyte is now known as an antigen-presenting cell

Question 11

how are T-Cells activated?

Answer 11

by binding to antigens on antigen-presenting cells

Question 12

What 4 processes are activated once a T-Cell has been activated?

Answer 12

• activated T-Cells divide by mitosis to produce T_H clones
• it releases cytokines to activate the T_C Cells
• activation of B-Cells
• simulation of phagocytosis

Question 13

How does a T-Cell kill a pathogen?

Answer 13

The protein perforin is produced. This makes holes in the cell membrane of foreign cells, resulting in cell death

Question 14

Describe the process of humoral immunity

Answer 14

1. B-Cell with complimentary antibody engulfs protein
2. B-Cell presents antigen, becoming an antigen-presenting cell
3. T-Cell binds to presented antigen using receptor proteins
4. T-Cell activates B-Cell to divide (mitosis) into plasma cells and memory cells
5. Plasma Cell clones made to secrete antibodies (primary response)
6. Antibodies attach to antigens and destroy the pathogen
7. Memory cells circulate the blood for future infections (secondary response)

Question 15

How does an antibody kill a pathogen and reduce the damage it does?

Answer 15

• agglutinates the pathogens to the target
• stops pathogens from invading body cells by marking it as foreign
• binds to free toxic proteins

Question 16

Describe the process of cell mediated immunity

Answer 16

1. Phagocyte engulfs pathogen
2. Phagocyte presents antigen, becoming an antigen presenting cell
3. Receptors on T-Cells bind to antigens, becoming activated
4. T-Cells then activate B-Cells, stimulate phagocytosis, release cytokines to activate T_C Cells, create T_H clones
5. T_C Cells release the protein perforin to kill the pathogen

Question 17

Describe the structure of an antibody

Answer 17

Composed of 4 polypeptide chains:

2 heavy

2 light

Joined by disulphide bonds to form a Y shaped structure where the stem is the constant region and the ends of the arms are the variable regions

Question 18

Define a monoclonal antibody

Answer 18

Antibodies produced from a single group of genetically identical B-Cells (plasma cells) which are specific to 1 type of antigen

Question 19

Why are monoclonal antibodies identical in structure?

Answer 19

They have the same primary structure as they are coded for by the same genes

Question 20

Describe how monoclonal antibodies are produced

Answer 20

the specific antigen binds to the receptor on the B-Cell

a T_H-Cell sends a chemical signal to activate B-Cells to release specific antibodies

So by using the same plasma cells, identical antibodies will be produced