Immune System Book 6

Question 1

What are pathogens?

Answer 1

Microorganism what cause disease

Question 2

How do pathogens cause disease?

Answer 2

1. ) host cells by entering, reproducing and leaving(cells burst)
2. ) produce and release toxins which damage host cells

Question 3

5 ways pathogens can transmit?

Answer 3

1. ) contaminated food and water eg chlorea
2. ) air borne eg flu
3. ) sexual intercourse eg hiv
4. ) blood to blood eg hiv
5. ) mother to foetus eg rubella

Question 4

What are antigens?

Answer 4

Molecules that cause an immune response

Question 5

5 facts about antigens

Answer 5

• located in the cell membrane of pathogens
• found on the surface of viruses
• exist as free molecules, such as a toxin
• found on the surface of a tissue or organ transplant
• found in the cell membrane of cancer cells

Question 6

Name 3 non specific defence mechanisms and how they work

Answer 6

Skin- contains dead cells which contain keratin acting as a barrier
Mucus-lining of respiratory passages, traps MOs
Lysozyme-present in saliva and tears containing enzymes which kill microbes

Question 7

2 specific defensive mechanism s

Answer 7

Cellular and humoral response

Question 8

2 types of white blood cells

Answer 8

Phagocytes- antigen presenting cells

Lymphocytes- include t and B cells

Question 9

Where do b and T cells come from

Answer 9

Bone marrow

Question 10

5 types of t and B cells

Answer 10

Cytotoxic T, helper T, memory T, B cells, memory b

Question 11

What makes T cells specific?

Answer 11

• specific receptor proteins on their surface membrane

- receptor proteins have specific tertiary structure so shape or binding site is specific

Question 12

What makes B cells specific?

Answer 12

Have antibody proteins in their surface membrane. The antibody has specific tertiary structure so shape of binding sites is specific.

Question 13

Explain th structure of an antibody

Answer 13

It is a protein with a quaternary structur, each molecule is made up of 4 polypeptide chains to form a Y shaped molecule. Each antibody has 2 binding sites so that more than one antigen-antibody complex can form at once stopping the mov met of more than one pathogen.

Question 14

Where can antibodies be found?

Answer 14

• surface of membranes of B cells
• blood stream
• in tissue fluid
• in breast milk

Question 15

What’s a vaccine?

Answer 15

A preparation of antign from a pathogen that will generate a primary immune response when injected into an individual

Question 16

Process of phagocytosis?

Answer 16

1- phagocytes are attracted to chemicals released by pathogens
2- phagocytes engulf pathogens and enclose them inside a membrane vesicle
3- lysosomes fuse with the phagosome releasing their hydrologic enzymes into it
4- enzymes digest the pathogens molecules killing the pathogen
5- pathogens antigens are displayed on the surface of the phagocytes cell membrane
6- T cell and B cells can bind to the antigen and this stimulates an immune response

Question 17

What’s clinal selection?

Answer 17

When t and B cells divide rapidly by mitosis producing genetically identical cells

Question 18

When does a secondary immune response occur ?

Answer 18

When T and B cells encounter the same pathogen again. Memory cells are activated when their surface receptor or antibody binds to antigen on the pathogen causing T cells to rapidly activate B cells. More antibody antigen complexes form faster so the pathogen is quickly killed

Question 19

What is antigen variability?

Answer 19

When pathogens undergo mutations which changes their antigen protein shape. Stops secondary immune response from being stimulated

Question 20

When does the secondary immune response form again?

Answer 20

When T and B cells encounter the same pathogen

Question 21

Explain the secondary immune response

Answer 21

Memory T and B cells are activated when their surface receptor or antibody binds to antigen on the pathogen. This causes T cells to rapidly activate B cells. B cells rapidly produce and then release more antibodies. More antibody-antigen complexes form faster, this kills the pathogen quickly before any symptoms can be produced.

Question 22

What does antigen variability mean?

Answer 22

Surface proteins on memory cells will not be able to bind to antigens on a pathogen and thus a secondary immune response cannot be stimulated and instead of primary response is triggered

Question 23

5 types of vaccine?

Answer 23

1- killed pathogen, antigens on surface still stimulate immune response 
2-live virus 
3- modified toxin 
4- isolate pathogen antigens 
5- genetically engineered antigens

Question 24

When is vaccination not successful?

Answer 24

Certain peopl have weak immune systems, memory cells eventually die, pathogens show antigen variability, when individuals opt ou of vaccination

Question 25

Passive immunity vs active

Answer 25

Passive doesn’t require exposure to antigen, protection is immediate, memory cells are mot produced, protection is short term. Active is the opposite.

Question 26

What are monoclonal antibodies?

Answer 26

Antibodies that are identical because they are produced by one type of B cells that are clones

Question 27

Uses of monoclonal antibodies

Answer 27

Cancer treatment- anti canc t drugs are attached to monoclonal antibodies.
Medical, diagnosis- ELISA checks if a patient has an antibody to a certain antigen in their body