Structure and function of membranes Flashcards Preview

Chapter 5 Plasma Membranes > Structure and function of membranes > Flashcards

Flashcards in Structure and function of membranes Deck (18):
1

What do membranes do?

-Separate contents of cells from their environment.
-Separate different areas within organelles.

2

What are the functions of membranes within cells?

-Compartmentalisation.
-Site of chemical reactions.
-Forms vesicles.
-Control what substances leave and enter organelles.

3

What is the plasma membrane?

-Cell surface membrane which separates cell from the external environment.

4

What are membranes formed from?

-Phospholipid bilayer.

5

What is the structure of the phospholipid bilayer?

-Hydrophilic phosphate heads point outwards and fatty acid hydrophobic tails point inward to form a hydrophobic core.

6

Are phospholipids soluble?

-Soluble because the heads can interact with water.

7

What is the fluid mosaic model?

-Phospholipids are free to move within bilayer which gives the membrane flexibility and shape.

8

What are the main components of a cell membrane?

-Phospholipid bilayer consisting of hydrophobic tails and hydrophilic heads.
-Extrinsic and intrinsic proteins.
-Cholesterol.
-Glycoproteins.
-Glycolipids.

9

What are intrinsic proteins?

-Proteins embedded through both layers in the membrane.
-Have amino acids with hydrophobic R-groups on external surfaces which interact with hydrophobic core in membrane.

10

What are examples of intrinsic proteins?

-Channel proteins.
-Carrier proteins.
-Glycoproteins.
-Glycolipids.

11

What are channel proteins?

-Provide hydrophilic channel that allows diffusion of ions through membrane.
-Held in position by interactions between hydrophobic core and hydrophobic R-groups in protein.

12

What are carrier proteins?

-important role in passive and active transport into cells.
-Involves change of protein shape.

13

What are glycoproteins?

-Embedded in membrane with attached carbohydrate chains.
-Play a role in cell adhesion and as receptors for chemical signals. Also, cell signalling.

14

What are glycolipids?

-Lipids with attached carbohydrate chains.
-Cell markers and can be recognised by immune system.

15

What are extrinsic proteins?

-Proteins present in one side of the bilayer.
-Have hydrophilic R-groups on external surface and interact with polar heads of phospholipid.

16

What is cholesterol?

-Lipid with a hydrophobic and hydrophilic end.

17

What is the role of cholesterol?

-Regulates fluidity of membrane.
-Adds stability to membrane.

18

How is cholesterol positioned in a membrane?

-The hydrophilic end interacts with head and hydrophobic end interacts with tail, pulling them together.