Cell recognition and the Immune system

Question 1

Name some of the bodies defence mechanisms against pathogens

Answer 1

Physical and chemical defences, Inflammation (swelling and heating) and recognising foreign cells known as ‘specific immune response’

Question 2

Give examples of physical defences

Answer 2

Skin and Mucus Membranes

Question 3

Give examples of chemical defences

Answer 3

Tears, saliva and sweat containing lysozyme, destroys bacteria

Question 4

What is the name given to the bodies own cells

Answer 4

self

Question 5

What is the name given to foreign cells

Answer 5

non-self

Question 6

How can the body recognise foreign cells

Answer 6

Due to specific molecules located on the surface of cells (usually proteins)

Question 7

What contains the surface molecules to be recognised as foreign

Answer 7

Pathogenic cells, abnormal body cells, toxins, cells from individuals from the same species

Question 8

What are these surface molecules known as

Answer 8

Antigens

Question 9

Give an example of abnormal body cells

Answer 9

Cancerous or pathogen infected cells

Question 10

What form are toxins in

Answer 10

Chemical rather than cellular. (Released by bacteria)

Question 11

Give an example of when cells from other individuals may enter the body

Answer 11

Organ transplants

Question 12

What do antigens allow for

Answer 12

cell-to-cell recognition

Question 13

Where do eukaryotes contain their antigens

Answer 13

Cell membranes

Question 14

Where do prokaryotes contain their antigens

Answer 14

Cell walls

Question 15

What can also act as antigens on cell surface membranes

Answer 15

Glycolipids and Glycoproteins

Question 16

What are the two forms of antigen

Answer 16

Self antigens or Non-self antigens

Question 17

What is antigen variability

Answer 17

Antigens present on the surface changing frequently due to genetic mutations.

Question 18

Do some pathogens exhibit genetic variability

Answer 18

Yes

Question 19

How does genetic variability pose as a problem for the immune system

Answer 19

Lymphocytes and memory cells produce one specific immune response. Therefore, the surface receptors are complementary in shape to just one antigen. When the antigen changes the lymphocyte and memory cells can no longer bind. So, no secondary immune response.

Question 20

Give examples of common pathogens that exhibit antigen variability

Answer 20

The cold virus and influenza virus

Question 21

What are the two main types of phagocyte

Answer 21

Neutrophils and Macrophages

Question 22

What is the role of phagocytes

Answer 22

To recognise and engulf pathogens (phagocytosis)

Question 23

What are phagocytes and where are they produced

Answer 23

White blood cells. Produced in bone marrow

Question 24

What is the 1st step of phagocytosis

Answer 24

Chemicals released by pathogens, as well as chemicals released by body cells e.g. histamines, attract phagocytes. (Chemotaxis)

Question 25

What is the 2nd step of phagocytosis

Answer 25

Phagocytes move toward the site of infection, where pathogens can be identified due to antigens. Phagocytes have receptor proteins on surface to recognise pathogens as non-self.

Question 26

What is the 3rd step of phagocytosis

Answer 26

The phagocyte attaches to the pathogen by binding to its antigens. Once attached the cell surface membrane of the phagocyte extends our and around the pathogen engulfing it. (Endocytosis)

Question 27

What is the phagocytic vacuole formed when the phagocyte engulfs the pathogen called

Answer 27

Phagosome

Question 28

What is the 4th step of phagocytosis

Answer 28

The phagocytic vacuole fuses with a lysosome to form a phagolysosome. The lysosome releases digestive enzymes called lysozymes e.g. by hydrolysis of bacterial cell walls.

Question 29

What is a lymphocyte

Answer 29

Another type of white blood cell

Question 30

Which is smaller lymphocytes or phagocytes

Answer 30

Lymphocytes

Question 31

What is the lymphocytes nucleus like

Answer 31

A large nucleus that fills most of the cell

Question 32

When are lymphocytes produced

Answer 32

In the bone marrow before birth (weeks 25-32)

Question 33

What are the two types of lymphocytes

Answer 33

T-Lymphocytes (T-Cells) and B-Lymphocytes (B-Cells)

Question 34

Where do immature T - Lymphocytes mature

Answer 34

They leave the bone marrow and mature in the thymus

Question 35

What do mature T - Lymphocytes have

Answer 35

T cell receptors

Question 36

What is the structure of T cell receptors similar to

Answer 36

They are similar to antibodies and are specific to one antigen

Question 37

When are T -Lymphocytes activated

Answer 37

When they bind to their specific antigen that is being presented by one of the hosts cells

Question 38

How do activated T-lymphocytes divide

Answer 38

Mitosis

Question 39

What two main types of T cell do T-Lymphocytes differentiate into

Answer 39

Helper T cells and Cytotoxic T cells (also known as killer T cells)

Question 40

What do helper T cells do

Answer 40

Assist other white blood cells in the immune response by releasing cytokines which stimulate: The maturation of B lymphocytes The production of memory B cells The activation of cytotoxic T cells An increased rate of phagocytosis

Question 41

What do T killer cells do

Answer 41

Patrol the body, attach to the foreign antigens on the cell surface membranes of infected cells and secrete toxic substances that kill the infected body cells, along with the pathogen inside.

Question 42

What do Perforins do and what are they secreted by

Answer 42

Secreted by T killer cells and punch a hole in the cell surface membrane of infected cells, allowing toxins to enter

Question 43

Where do B - Lymphocytes remain while they mature

Answer 43

In bone marrow

Question 44

Where do B - Lymphocytes go once they have matured

Answer 44

They spread through the body, concentrating in lymph nodes and the spleen

Question 45

What do B -Lymphocytes do

Answer 45

Mature the genes coding for antibodies and are changed to code for different antibodies

Question 46

What can B Lymphocyte cells do once mature

Answer 46

Each type of B lymphocyte cell can make one type of antibody molecule. At this stage, the antibody molecules do not leave the B-Lymphocyte cell but remain in the cell surface membrane.

Question 47

What does part of each antibody molecule form

Answer 47

A glycoprotein receptor

Question 48

What will happen between antigens and B - Lymphocytes if an antigen enters the body

Answer 48

B - Lymphocyte cells with the correct cell surface receptors will recognise and bind to it (clonal selection)

Question 49

How do B -Lymphocytes divide

Answer 49

Clonal expansion

Question 50

What two main types of cell do B -Lymphocytes differentiate into

Answer 50

Plasma cells and Memory cells

Question 51

what happens when an antigen enters the body for the first time

Answer 51

The small number of B-Lymphocytes with receptors complementary to that antigen are stimulated to divide by clonal expansion

Question 52

What do some of the B-Lymphocytes become after being screed in the primary response and what do they do

Answer 52

Plasma cells that secrete lots of antibodies into the blood, lymph or linings of the lungs and the gut

Question 53

How long do the plasma cells last in the primary response

Answer 53

Their numbers drop off after several weeks, but the antibodies they have secreted stay in the blood for longer

Question 54

What do other B -Lymphocytes become if they dont become plasma cells in the primary response

Answer 54

Memory cells

Question 55

is the primary response quick

Answer 55

No, it is a relatively slow response