2C - Cells and the Immune System

Question 1

What are antigens?

Answer 1

Proteins on the surface of cells that can generate an immune response and are specific to that type of cell.

Question 2

What are foreign antigens?

Answer 2

Antigens not normally found in the body.

Question 3

Cells from our body are called …

Answer 3

Self cells

Question 4

Cells from other organisms are called …

Answer 4

Non-self cells

Question 5

A pathogen is…

Answer 5

an organism that causes disease.

Question 6

Three examples of pathogens

Answer 6

Bacteria
Fungi
Viruses

Question 7

Abnormal body cells

Answer 7

Cancerous of pathogen infected cells that have abnormal antigen to trigger an immune response.

Question 8

What is a phagocyte?

Answer 8

A type of white blood cell which carries out phagocytosis. Found in the blood and tissues.

Question 9

What are lymphocytes

Answer 9

White blood cells

Question 10

Stages of phagocytosis

Answer 10

1) Phagocyte recognises foreign antigens on a pathogen
2) Cytoplasm of the phagocyte moves around the pathogen
3) A phagocytic vacuole is formed around the pathogen and lysosomes containing digestive enzymes fuse with the vacuole.
4) Enzymes are released from the lysosomes into the vacuole which break down the pathogen
5) Phagocyte presents the antigens of the pathogen on its surface to generate an immune response. It becomes an antigen presenting cell.

Question 11

What do T Helper cells do?

Answer 11

Bind to complementary antigens and release chemical signals that stimulate T-Killer cells, B-cells and phagocytes

Question 12

What do T-Killer (cytotoxic) cells do?

Answer 12

Bind to foreign antigens and release digestive enzymes into the pathogen which destroys it.

Question 13

What are B-lymphocytes?

Answer 13

A type of white blood cell that when stimulated by T-Helper cells will mature into plasma cells which produce antibodies which are specific to the pathogen it is bound to. This is called clonal selection.

Question 14

Monoclonal antibodies are…

Answer 14

Antibodies produce from a single group of genetically identical cells

Question 15

Agglutination

Answer 15

When pathogens become clumped together. This is because each antibody has 2 binding sites.

Question 16

Cellular Responses

Answer 16

T-Cells

Phagocytes

Question 17

Humoral Responses

Answer 17

B-cells
Clonal selection
Monoclonal Antibodies

Question 18

Primary Response

Answer 18

When a pathogen enters the body for the first time.
It is slow as there aren’t as many B-cells to produce antibodies for the pathogen. The body will eventually produce the right antibodies and overcome the infection

Question 19

Secondary Response

Answer 19

The next time the same pathogen enters the body

This response is quicker than the first as clonal selection happens faster due to memory cells being present.

Question 20

What are memory cells?

Answer 20

Special types of B and T cells which remember the specific antigen and will recognise it the next time it enters the body allowing a quicker immune response.

Question 21

What is natural active immunity?

Answer 21

When you become immune after catching a disease.

Question 22

What is artificial active immunity?

Answer 22

When you become immune after being given a vaccination which causes you to produce antibodies.

Question 23

What is natural passive immunity?

Answer 23

When a baby becomes immune due to antibodies on breast milk from the mother.

Question 24

What is artificial passive immunity?

Answer 24

When you become immune after receiving an injection containing antibodies from someone else.

Question 25

Herd Immunity

Answer 25

Vaccines protect individual who have them which reduces the occurrence of the disease which protects those who don't have the vaccine

Question 26

Explain the ethical issues of vaccines.

Answer 26

Vaccines must be testes on animal before humans and animal based products may be used in the vaccines which people disagree with. Testing vaccines can be dangerous as people who have it may put themselves at unnecessary risk as they think they're protected and the vaccine doesn't work. Some vaccines may have side effects. In an epidemic decisions would have to be made about who would receive it first.

Question 27

Some pathogens can change their surface antigens. This is called...

Answer 27

Antigenic variation

Question 28

How does antigenic variation occur.

Answer 28

Mutations in the genes of the pathogen

Question 29

What is the problem with antigenic variation.

Answer 29

When you are infected for a second time the memory cells will not recognise the antigens and so an immune response is slower as a new primary response is required

Question 30

Antigenic variation make it difficult to develop.....

Answer 30

Vaccines

Question 31

Uses of monoclonal antibodies.

Answer 31

Medical treatment and diagnosis.

Question 32

Why are monoclonal antibodies used to treat cancer?

Answer 32

Cancer cells have tumour marker which are not found on normal cells. Monoclonal antibodies can be produced which are complementary to the tumour markers. Anticancer drugs are attached to the antibodies. The antibodies bind to the tumour marker when the come in contact so the drug will only accumulate in areas where cancerous cells are. So the side effects of the drug are lower are less healthy cells are damaged.

Question 33

What does an ELISA test show?

Answer 33

If a patient has any antibodies to a specific antigen or antigens to a certain antibody.

Question 34

Name the 2 types of ELISA

Answer 34

Direct | In-direct

Question 35

Describe direct ELISA

Answer 35

Antigens from the patient are bound to the inside of a well. A detection antibody with an enzyme attached , that is complementary to the antigen being tested for is added. If the antigen being tested for is present the antibodies will bind to them on the side if the well and become immobilised. The well is washed out to remove any of the unbound antibodies and a substrate solution is added. If the detection antibody is present a colour change will occur and this means the antigens being tested for are present.

Question 36

Describe indirect ELISA

Answer 36

Tests for the presence of a specific antibody. The known complimentary antigen to the antibody being tested for is bound to the well. Sample of the patients blood is added. If the antibodies are present in the blood they will bind to the antigens. The well is washout to remove any unbound material. A secondary antibody with an enzyme attached is added and this will bind to any antibodies that are being tested for. A substrate solution is added and a colour change show the antibodies are present.

Question 37

What is HIV?

Answer 37

A virus that kills T-helper so the immune system is unable to produce an immune response to other pathogens.

Question 38

What is the latency period?

Answer 38

A period when HIV replication drop to a low enough level so that no symptoms are experienced.

Question 39

Describe HIV structure

Answer 39

Virus particle has a spherical structure. HAs a core of RNA and proteins such as reverse transcriptase Outer protein coating called a capsid An extra outer layer called an envelope Attachment proteins on the envelope to bind to helper T-cells

Question 40

Stages of HIV replication.

Answer 40

1. Attachment proteins bind to receptor molecule on the T-helper cells. 2. Capsid is released into the cell where it uncoats and RNA is released into the cytoplasm 3. Reverse transcriptase is used to make a complementary DNA strand of the RNA 4. A double strand of DNA is made and is inserted into the human DNA 5. Host cell enzyme are used to make the viral DNA 6. Viral proteins are assembled into new viruses which are released into the rest of the body.

Question 41

How do antiviral drugs work?

Answer 41

Trget virus specific enzymes