Lesson 2: Roles of Membranes

Question 1

Why do cells need membranes

Answer 1

-act as partially permeable barrier between cell and environment
-act as partially permeable barrier between organelle and cytoplasm
-site of chemical reactions
-site of cell to cell communication (cell signalling)

Question 2

Cell Signalling

Answer 2

-one cell will release a molecule which will attach to another cell bringing about a change
-some messengers can pass directly through the cell membrane because they are small enough
-most cannot and must bind to membrane-bound receptors

Question 3

G protein-coupled receptors

Answer 3

-E.g adrenaline
-signal molecule binds to the receptor and the receptor becomes activated and triggers a response inside the cell

Question 4

Ion Channels

Answer 4

-E.g acetylcholine
-signal molecule binds to the receptors and this causes an ion channel to open, allowing ions to enter the cell

Question 5

Drug Targets

Answer 5

-membrane receptors are involved in many diseases and are targets for medical drugs
-drugs that bind to receptors and mimic the body’s normal messengers are called agonists
-type 1 diabetics inject insulin which binds to insulin receptors on target cells and increases the uptake of glucose in those cells
-Drugs that bind to receptors and block the bodies normal messengers are call antagonists
-beta blockers are used to reduce blood pressure by stopping noradrenaline from binding to its receptor