Topic 2C

Question 1

Pathogens

Answer 1

Disease causing micro-organisms

Question 2

Phagocytes engulf pathogens

Answer 2

Pathogens give off chemoattractants attracting phagocytes
Phagocyte engulfs pathogen forming a vesicles around the phagosome
Lysosome fuses with the phagosome digesting it
Digested material leaves via exocytosis

Question 3

Phagocytes activate T-Cells

Answer 3

T helper cells have receptor proteins on the surface that bind to complementary antigens
Cytotoxic T cell activated them

Question 4

Cytotoxic cells

Answer 4

Kill abnormal body cells

Produce perforin which makes holes in cell surface membrane making it freely permeable and killing it

Question 5

Activated B-Cells

Answer 5

Covered in antibodies
Will meet antigen in the blood with complementary shape to antibody (antigen-antibody complex)
Antigen enters B cell via endocytosis and presented on surface when processed
Th binds to antigen and stimulate B cell divide to divide via mitosis
Clones formed (clonal selection) some become plasma cells and some memory cells

Question 6

Plasma cells

Answer 6

Secret antibodies into blood plasma which are specific to the antigen (only survive for days)
Form antigen-antibody complexes
Only in immediate response

Question 7

Antibody structure

Answer 7

Each antibody has unique tertiary structure due to amino acid structure 
4 variable region 
Heavy chain
Light chain 
Disulfide bridges

Question 8

Cellular response

Answer 8

The t-class and other immune system cells they interact with eg phagocytes from cellular response

Question 9

Humoral response

Answer 9

B cells clonal selection and the production of monoclonal antibodies from humoral response

Question 10

Primary immune response

Answer 10

Happens when antigen first enters body
Slower as not many B-Cells to make antibody needed, enough eventually made to overcome infection but symptoms
T and B cells produce memory cells which stay in body. Remember antigen and antibody needed
Person is immune and have ability to respond quickly

Question 11

Secondary Immune response

Answer 11

Same pathogen renters response quicker and stronger
Clonal selection happens faster. Memory B cells activated and divide into plasma cells that produce right antibody
Memory T cells activated and divide to correct type to kill cell carrying antigen
Happens before any symptoms

Question 12

Antigenic variation

Answer 12

Some pathogens can change surface antigens

Question 13

Active immunity

Answer 13

When your body produces it own antibodies after being stimulated by antigen
Natural- when you become immune after catching disease
Artificial- immune after getting a vaccine
Memory cells produced and long term protection

Question 14

Passive immunity

Answer 14

Immunity from when you get antibodies made by a different organism, don’t produce your own antibodies
Natural - baby immune after recieving antibodies from mother
Artificial- get antibodies from someone else
Short term protection and immediate

Question 15

Monoclonal antibodies

Answer 15

Antibodies produced from a single group of genetically identical B cells (plasma cells)

Question 16

Cancer cells

Answer 16

Have tumour markers.
Monoclonal antibodies can be made to bind to tumour markers. Can attach anti cancer drugs to antibodies
Antibodies in contact with cancer cells bind to tumour markers meaning drug will accumulate around cancer cells

Question 17

Pregnancy tests

Answer 17

Human chorionic gonadotropin (hCG)
Application area contain antibodies for hCG bound to AB1
Urine tracks up to the test zone where there’s more antibodies that are immobilised hCG sandwiched
If no hCG passed through to control zone

Question 18

Indirect ELISA test

Answer 18

Uses antigens
Add sample, complementary antibodies will bind
Unbound antibodies washed out
Add secondary antibody thats bound to enzyme binding to the complex
Add substrate which stimulates a colour change

Question 19

Direct ELISA test

Answer 19

Uses monoclonal antibodies
Add sample if complementary antigens present will bind
Wash out unbound antigens
Add complementary antibody bound to enzyme
Binding to enzyme
Add substrate stimulating colour change

Question 20

HIV Structure

Answer 20

Core containing RNA and reverse transcriptase enzyme 
Capsid 
Matrix 
Phospholipid bilayer 
Attachment

Question 21

HIV replication

Answer 21

Attachment protein attaches to CD4 protein T Cell
Caspid fuses with surface membrane, RNA and enzyme of HIV enter cell
Reverse transcriptase makes complementary strand of DNA from RNA template
New DNA injected into t helper cell nucleus using viral integrase
mRNA created using enzymes to make new viral proteins
mRNA passes out the nucleus through nuclear pore and uses protein synthesis mechanisms to make long chains of HIV proteins
HIV particle break away from T helper cell with piece of cell membrane around it.
Viral protease breaks up long chains and smaller chains combine to make mature virus and goes to infect other cells

Question 22

Early symptoms of AIDS

Answer 22

Minor infections of mucous membranes (inside nose ear and genitals)
Recurring respiratory problems

Question 23

Anti viral drugs

Answer 23

Target cutie specific enzymes eg reverse transcriptase