Chapter 5 - Cell Recognition and the Immune System

Question 1

Define antigens

Answer 1

Any protein on the surface on the cell which causes an immune response

Question 2

Why are antigens important?

Answer 2

• Allows recognition from bacteria/fungi/viruses
• Cells from other individuals from the same species
• Toxins
• Abnormal body cells

Question 3

Define pathogen

Answer 3

Any organisms that causes disease

Question 4

How does a pathogen cause disease?

Answer 4

Either destroys body cells or produces toxins

Question 5

What are the stages of the immune response?

Answer 5

Phagocytosis
T cells
Cellular response

B cells
Plasma cells
Humoral response

Question 6

Summarise phagocytosis

Answer 6

• Front line, general defence
• Phagocyte identifies foreign antigen
• Engulfs into a phagosome
• Lysosomes fuse with the phagosome and is hydrolysed by lysozymes
• Phagocyte presents antigens on its cell surface membrane

Question 7

Summarise how T cells are involved in the immune system

Answer 7

• Activated by antigens presented by phagocyte due to complementary receptor to the antigen
• Two types: one activates B-cells and cytotoxic T cells that kill pathogens

Question 8

Summarise how B cells are involved in the immune system

Answer 8

• Produces antibodies that bind to antigens and kill pathogens
• Each B cell produces their own specific antibody
• The B-cell with the complementary antibody forms an antigen antibody complex
• Activates specific B cell and causes B cells to divide into plasma cells by mitosis

Question 9

What is clonal selection?

Answer 9

When only the B-cell that forms an antigen antibody complex is selected to divide into plasma cells

Question 10

What are plasma cells?

Answer 10

Clones of a B cell which produce complementary antibodies to pathogen antigens

Question 11

What are monoclonal antibodies?

Answer 11

Identical antibodies made from the same specific B cell

Question 12

How do antibodies help in the immune system?

Answer 12

They cause agglutination so phagocytes can destroy many pathogens at once

Question 13

What occurs after an immune response?

Answer 13

Memory B cells remain in the blood for future infection

Question 14

Define antibody

Answer 14

A protein with a specific structure that binds to an antigen

Question 15

What is the primary response?

Answer 15

• First immune response to infection
• Slow due to the four stages of the immune response
• Pathogen multiplies and causes symptoms
• After the infection, memory cells are saved

Question 16

What is the secondary response?

Answer 16

• Same pathogen infects
• Immune response is faster and stronger
• Memory B cells and memory T cells produce antibodies and kill pathogens
• No symptoms

Question 17

What are the uses of monoclonal antibodies?

Answer 17

• Deliver drugs to the body
• Can create an antibody to bind to any target cell such as cancerous cells
• Medical diagnoses

Question 18

Why are monoclonal antibodies beneficial?

Answer 18

• They carry a drug and only affect target cells

Question 19

How are monoclonal antibodies used in the diagnosis of disease?

Answer 19

• Monoclonal antibodies fixed to a plate
• Sample added and if antigen present, complex forms
• Rinse plate to remove unbound antigens
• Another monoclonal antibody added with complementary region but with a colour attached
• Rinsed to remove unbound antibodies
• Observe and see if a marker is present, or if an enzyme is present add the substrate to see an effect