Topic 2- Cell recognition

Question 1

What are the body’s defence mechanisms against pathogens?

Answer 1

-Preventing the entry of pathogens by a variety of physical and chemical defences, such as the skin, mucous membranes, tears (containing the enzyme lysozyme, which destroys bacteria) and saliva
-Inflammation (swelling and heating) of the region invaded by the pathogen, a process known as a non-specific inflammatory response
-Recognising ‘foreign’ cells and targeting any pathogenic cells, a process known as a specific immune response

Question 2

Why is it possible to recognise foreign cells?

Answer 2

specific molecules found on the surface of cells (and viral particles) that enable them to be identified by the body

Question 3

What biological molecules usually are these specific molecules?

Answer 3

Proteins- usually part of the phospholipid bilayer such as glycoproteins

Question 4

What is the function of these surface proteins?

Answer 4

allow the body to recognise its own cells (‘self’) and foreign cells (‘non-self’)

Question 5

These surface proteins are found on (and enable the body to recognise) the following:
1._____ cells
2.______ body cells, such as cancerous or pathogen-infected cells
3.______ (these are chemical rather than cellular, in nature)
4. Cells from _______ from the same species (for organ transplants to occur successfully the body must not recognise the cells and tissues of the donated organ as foreign so that no immune response occurs)

Answer 5

1.Pathogenic
2.Abnormal
3.Toxins
4.other individuals

Question 6

The surface molecules used by the body to identify cells, viral particles and toxins are known as what?

Answer 6

Antigens