3.2.4 Cell Recognition

Question 1

What is a Pathogen

Answer 1

a disease causing microorganism

Question 2

What are Antigens?

Answer 2

-proteins on the surface if a cell that is recognized as non-self by immune system and stimulate an immune response

Question 3

Where are antigens found?

Answer 3

-Pathogens
-cells from other organisms
-abnormal body cells (tumors)
toxins from bacteria

Question 4

What are Phagocytes?

Answer 4

type of white blood cells that are attracted by chemicals released by pathogens (or dead/damaged cells)
NON SPECIFIC

Question 5

How does phagocytosis work?

Answer 5

1) ENDOCYTOSES, pathogen engulfed
2) PHAGOSOME FORMATION, vesicle
3) PHAGOSOME-LYSOSOME MERGE
4) break bacterial wall and reuse useful products
5) DEBRIS DIGESTION+ANTIGEN PRESENTATION

Question 6

the 2 types of Lymphocytes and where they mature

Answer 6

both produced by stem cells in bone marrow
-B CELLS mature in marrow
T CELLS mature in Thymus Gland

Question 7

T-Lymphocytes

Answer 7

mediated response

• have receptors which respond to antigens
• Helper T-Cells clones itself once attached to antigen

Question 8

What do Helper T Cells do?

Answer 8

• develop into memory T Cells
• stimulate phagocytosis
• activate B Cells
• causes Tc to kill infected cells

Question 9

How do Cytotoxic T Cells kill bacteria?

Answer 9

• release chemical cytokines (e.g. perforin which makes holes in cell membrane of bacteria)

Question 10

B-Lymphocytes (+how they clone)

Answer 10

humeral response
produce antibodies which cause AGGLUTINATION and act as MARKER for lymphocytes
-b cells take in antigens by endocytosis and present them on surface, once T-helper cells bind to them, b cells form clone CLONAL SELECTION

Question 11

Antibody structure

Answer 11

2 heavy chains and 2 short chains
constant region binds to B-cell, variable region is SPECIFIC+COMPLIMENTARY to antigen of foreign cell
forms antigen-antibody complex when binds