3.2.4 Cell Recognition and The Immune System

Question 1

Antigens are molecules that trigger an immune response by…

Answer 1

Lymphocytes

Question 2

Pathogens are…that cause disease

Answer 2

Agents
(We can’t say microorganisms as viruses aren’t organisms as they are acellular)

Question 3

Process of phagocytosis (how phagocytes destroy pathogens)

Answer 3

1) Phagocyte membrane surrounds pathogen and engulfs it
2) A vesicle (phagosome) is formed inside the phagocyte which contains the pathogen
3) Lysosomes in the cytoplasm fuse with the vesicle phagosome (to form a phagolysosome) and release hydrolytic enzymes
4) The hydrolytic enzymes hydrolyse the pathogen

Question 4

Antigens are molecules that trigger an immune response by lymphocytes and can be found on the cell surface membranes of … , …. and…
Antigens can also be toxins in solution

Answer 4

Pathogens
Foreign cells (cells from other organisms of the same species- cells that aren’t your own body cells)
Abnormal body cells (e.g cells in uncontrolled cell division)

Question 5

True or false, antigens are only ever found on the cell surface membrane of cells and nowhere else

Answer 5

False
Antigens can be toxins in solution

Question 6

Is a non- specific immune response immediate (quick) or slow

Answer 6

Immediate/ quick
As the response is the same no matter what the pathogen is. The phagocytes just engulf the pathogen and destroy it, no matter what it is and any phagocyte can engulf and destroy any pathogen

Question 7

Is phagocytosis a specific or non specific immune response

Answer 7

Non specific
(As any phagocyte can engulf and destroys any pathogen no matter what the pathogen is)

Question 8

Are phagocytes involved in specific or non specific immune responses

Answer 8

Non specific
(Any phagocyte can digest and engulf any pathogen)

Question 9

Are T lymphocytes and B lymphocytes involved in a specific or non specific immune response

Answer 9

Specific
As the response is specific to each pathogen

Question 10

Antibodies are soluble proteins and are made up of chains of amino acids. Each antibody (protein) is made up of …(how many) polypeptides

Answer 10

4

Question 11

Each antibody has a …region with a unique tertiary structure (due to a different sequence of amino acids). This…region is complementary to one specific antigen

Answer 11

Variable

Question 12

Each antibody has a variable region with a unique …..

Answer 12

Tertiary structure

Question 13

Antibodies (the variable region of them which have a unique tertiary structure due to a specific sequence of amino acids) are…to the antigen

Answer 13

Complementary

Question 14

True or false, antibodies are complementary to the antigen

Answer 14

True
Each antibody has a different variable region (a unique tertiary structure due to a specific sequence of amino acids)

Question 15

….are a type of white blood cell that are covered with antibodies

Answer 15

B lymphocytes

Question 16

Antibodies are made up of 4 polypeptide chains which are joined together by ….and stabilise the protein (as antibodies are proteins)

Answer 16

Disulfide bridges

Question 17

Where on the antibody is the binding site (to bind to the antigen)

Answer 17

The variable region (where each antibody has a unique tertiary structure that’s complementary to a specific antigen)

Question 18

All antibodies have the same…regions but they have different variable regions (the variable regions are the binding site where the antibody binds to the antigen)

Answer 18

Constant

Question 19

An antibody binds to an antigen to form an…

Answer 19

Antigen- antibody complex

Question 20

Why can an antibody bind to 2 antigens at the same time

Answer 20

It has 2 binding sites

Question 21

True or false, an antigen is the same thing as a pathogen

Answer 21

False
Antigens are molecules found on the cell surface membrane of the pathogen

Question 22

The immune system initiates 2 types of response: a humoral response and a …response

Answer 22

Cellular

Question 23

The immune system initiates 2 types of response: a …response and a cellular response

Answer 23

Humoral