Unit 1 Section 2: Cell membranes and signalling

Question 1

importance of cell signalling

Answer 1

cells need communicate to control processes inside the body and respond to changes in the environment

Question 2

cell signalling starts…

Answer 2

when one cell releases a messenger molecule such as a hormone. this travels to another cell, where it is detected because it binds to a receptor on the cell membrane. this triggers a change in the cell, e.g. chemical signals sent off.

Question 3

membrane bound proteins…

Answer 3

act as receptors for messenger molecules

Question 4

receptor proteins

Answer 4

have specific shapes so that only messenger molecules with a complementary shape can bind to them. different cells have different types of receptor, meaning they respond to different messenger molecules. when a cell responds to a particular molecule it is called the TARGET CELL. cells can have many combinations of receptor cells they are not restricted to 1.

Question 5

examples of hormone messenger molecules

Answer 5

• Glucagon is a hormone released when there isn’t enoughglucose in the blood. It binds to receptors on liver cells causing liver cells to break down stores of glycogen to glucose.
• FSH hormone is released by the pituitary gland during the menstrual cycle. It binds wuth receptors on cells in the ovaries, causing an egg to mature, ready for ovulation.
• FSH can also bind to cells in the testes to initiate the production of sperm.

Question 6

role of drugs

Answer 6

some drugs also bind to receptors in cell membranes. they either trigger a response or block a receptor preventing it from working.

Question 7

drug examples

Answer 7

• Morphine binds to the same recepters an endorphins and triggers a reduction in pain signals that are sent.
• Antihistamines block histamine receptors on the surface of cells preventing histamine from binding, therefore reducing inflammation.

Question 8

define antagonistic molecules

Answer 8

a molecule that blocks the action of another.