Cell Recognition And Immune System

Question 1

What allows the immune system to identify things?

Answer 1

Each type of cell has specific molecules on its surface identify these molecules include proteins and enable the immune systems to identify things

Question 2

What do the protein molecules enable the immune system to identify

Answer 2

Pathogens
Cells from other organisms of the same species
Abnormal body cells
Toxins

Question 3

Describe non-specific defence mechanism

Answer 3

Response is immediate and the the same for all path

Question 4

Describe specific defence mechanism

Answer 4

Respond to slower and specific to each pathogen

Question 5

Examples of specific and non-specific defence mechanisms

Answer 5

Non-specific
-Physical barrier, e.g. the skin
-phagocytosis

Specific
-Cell mediated response, T lymphocytes
-humoural response, B lymphocytes

Question 6

Define antigen

Answer 6

Proteins on surface of foreign cell

Toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies

Question 7

What protein structure are antigens?

Answer 7

Quaternary structure as it has four polypeptide chains joined together

Question 8

How do b cells respond to foreign antigens?

Answer 8

There’s a variety of B cells a different shapes of receptor

T helper cells activate the cells and simulate them to divide by mitosis

cells with the right shape of receptors for antigen is stimulated to divide

plasma cells secrete antibody

antibodies cause pathogens to clump together this is them harmless and prepare them for destruction

Question 9

Describe the steps of phagocytosis

Answer 9

The phagocyte is attracted to the pathogens by chemoattractants moves towards a pathogen a longer concentration gradient. The phagocyte bind the pathogen.
Lysosomes within the phagocyte migrate towards the phagosome formed by engulfing the bacterium.
The lysosomes release the lyric enzymes where they break down the bacteria.
The breakdown products of the bacteria are absorbed by the phagocyte

Question 10

Define endocytosis

Answer 10

The movement of large molecules into cells using vesicles eg phagocytosis

Question 11

Define exocytosis

Answer 11

Movement of lodge molecules out of cells using vesicles the phago lysosomes fused with the cell membrane and release the debris from the broken down pathogen

Question 12

How do you T cells respond to a foreign antigen?

Answer 12

A phagocyte has engulfed a pathogen and displays the antigen on its surface

The antigen is displayed to many different T cells in the lymph node

Clonal selection -stimulated t cell divide many times

Helper T cells – these secrete chemicals which simulate phagocyte cells stimulate the cells to produce antibodies and activate killer t cells

Killer T cells - these bind to cells presenting the complementary antigen

T memory cells formed after injection

Question 13

Describe perforin

Answer 13

Causes perforation in the cell member and making the self full permanent

Question 14

Describe b lymphocytes

Answer 14

Matures in bone marrow
Involved in humoral immunity
Produce antibodies
Responds to foreign material outside body cells
Responds to bacteria and viruses

Question 15

Describe T lymphocytes

Answer 15

Matures in thyroid gland
involved in cell mediated immunity responsd to foreign material inside body cells
response to cells altered by viruses or cancer to transplanted tissue

Question 16

What protein structure are antibodies?

Answer 16

Quaternary structure proteins (4 polypeptide chain)

Question 17

What are antibodies secreted by?

Answer 17

B lymphocytes eg plasma cells in response to specific antigen

Question 18

What do antibodies bind to ?

Answer 18

Bind specifically to antigens forming antigen antibody complexes

Question 19

How do antibodies lead to the destruction of pathogens ?

Answer 19

Antibodies bind to antigens on pathogens forming an antigen antibody complex (specific tertiary structure so binding site /variable region binds to complementary antigen )

Attract phagocytes

Phagocytes bind to the antibodies and phagocytose many pathogens at once

Question 20

What is a monoclonal antibody?

Answer 20

Antibody produced from genetically identical /cloned B lymphocytes/plasma cells

So have same tertiary structure

Question 21

How can monoclonal antibodies be used in medical treatments?

Answer 21

Monoclonal antibody has a specific tertiary structure/binding site /variable region binds

Complementary to receptor /protein/antigen found only on a specific cell type(e.g cancel cell)

Therapeutic drug attached to antibody

Antibody binds to specific cell forming antigen antibody complex delivering drug

Some mAbs are also designed to block antigens/ receptors on cells

(

Question 22

How can mAbs be used in medical diagnosis?
(E.g pregnancy tests)

Answer 22

mAb has a specific tertiary structure /binding site/variable region

Complementary to specific reception /protein /antigen associated with diagnosis

Dye /stain/fluorescent marker attached to antibody Antibody binds

Antibody binds to receptor/protein/antigen forming antigen antibody complex