B2.1 Cell Membrane and Membrane Proteins

Question 1

What is the fluid mosaic model?

Answer 1

-fluid = motion and interaction of its parts
-mosaic = mixture of many components
-the cell membrane is made of a phospholipid bilayer, glycolipids, sterols, and proteins

Question 2

What is phospholipid like in water?

Answer 2

-has a hydrophilic head that is polar with phosphate molecule
-has a hydrophobic tail with two non polar hydrocarbon chains

Question 3

What is special about the phospholipid bilayer?

Answer 3

-hydrophobic groups (non-polar) do not want to be exposed to water filled environment (polar) and therefore will spontaneously form the bilayer format

Question 4

What is transport protein?

Answer 4

-it allows water soluble materials through, passive transport
-example, channel protein

Question 4

Structure of phospholipid bilayer

Answer 4

-hydrocarbon chains that form the core of the bilayer are hydro phobic and have a low permeability to large and charged (large compounds and hydrophilic particles) and substances

Question 5

What is cholesterol?

Answer 5

• sterol, lipid binding protein in animal cells, is wedged between the phospholipid to maintain its structure during temperature change and control the permeability to some solutes

Question 6

Where can membrane protein attach?

Answer 6

-can mover along the cell membrane but not very far due to size
-may attach to the cytoskeleton
-integral, embedded proteins partially or completely spanning the membrane usually involving transport (SORTA IN THE MEMBRANE)
-extrinsic, on the membrane surface or just inside (OUTSIDE PHOSPHATE END)

Question 7

What does protein attachment do?

Answer 7

-proteins embedded within the phospholipid bilayer may act as points of transport for large and charged substances
-this results in the lipid bilayer becoming a selective barrier as the membrane proteins can coordinate the transport of hydrophilic materials

Question 8

What is pumps protein?

Answer 8

-it is active transport for solutes

Question 9

What are recognition proteins?

Answer 9

-it is found on cell surface and contains carbohydrate chains (glycoproteins) or lipids (glycolipids) to identify a cell (cell fingerprint)
-white blood cells attack non recognizable cells

Question 9

What are protein receptors?

Answer 9

-binds extracellular substances to trigger changes in cell activities
-example : hormone binding sites

Question 10

What are electron transport proteins?

Answer 10

-it passes electrons from carrier to carrier

Question 11

What are enzyme proteins?

Answer 11

-it catalyzes chemical reactions along the membrane (ATP synthase)