Structure of cell surface membrane

Question 1

Cell surface membrane

Answer 1

surrounds cells and forms boundary between the cell cytoplasm and the enviroment

Question 2

phospholipids

Answer 2

• form a bilayer
  hydrophillic heads - point to outside of cell membrane attracted to water on both sides
  hydrophobic tails - point to inside cell membrane repelled by water on both sides

Question 3

Functions of phospholipids

Answer 3

• allow lipid soluble substances to enter and leave the cell
• prevent water-soluble substances entering and leaving the cell
• make membrane flexible and self-healing

Question 4

Proteins

Answer 4

Embedded in bilayer in two main ways:

• some lay on surface of bilayer and provide mechanical support or in conjunction to glycolipids, as cell receptors for molecules such as hormones
• some are protein channels and form a water-filled tube to allow water soluble ions to diffuse across. Others are carrier proteins that bind to ions or molecules like glucose, amino acids, then change shape in order to move these molecules to move across

Question 5

Functions of proteins

Answer 5

• structural support
• alllow active transport
• help cells adhere together
• act as receptors

Question 6

cholesterol

Answer 6

provide structural support

Question 7

Functions of cholesterol

Answer 7

• reduce lateral movement
• membrane less fluid at high temps
• prevent leakage of water

Question 8

glycolipids

Answer 8

carb portion extends into the watery environment outside the cell and acts as a receptor for specific chemicals

Question 9

functions of glycolipids

Answer 9

• recognition sites
• help cells attach to one another to form tissues
• maintain stability

Question 10

glycoproteins

Answer 10

• act as cell receptors for hormones and neurotransmitters

Question 11

permeability

Answer 11

• cell membrane controls what flows in and out
• some do not freely diffuse as they are not lipid soluble, too large to pass through the channels or same charge as the charge on the protein channels

Question 12

fluid mosaic model

Answer 12

fluid - phospholipid molecules can move relative to one another
mosaic - proteins embedded in the bilayer in all shapes and sizes in the same ways as the stones or tiles in a mosaic