.5 cell wall plasma membrane

Question 1

plasma membrane

Answer 1

component of all living cells that separates the inside of the cell (cytosol) from the outside of the cell
(extracellular environment). Is a selective barrier that allows the cell to:
regulate the passage of materials, divide the cell into compartments, serve as surfaces for chemical reactions, adhere to and communicate with other cells, and transmit signals between the environment and the interior of the cell. Membranes are also an essential part of energy transfer and storage systems.

Question 2

lipid bilayer

Answer 2

This arrangement allows the hydrophilic heads of the phospholipids to be in contact with the aqueous medium, while their oily tails, the hydrophobic fatty acid chains, are buried in the interior of the structure away from the water molecules. allows a cell to maintain different chemical environments within each membrane compartment.

Question 3

Amphipathic molecules

Answer 3

• Hydrophobic tails facing inwards

* Hydrophilic heads facing outwards

Question 4

3 classes of membrane lipids

Answer 4

• Phospholipids(phosphatidylcholine)
• Glycolipids
• Cholesterol

Question 5

fluid mosaic model

Answer 5

• Consists of phospholipid molecules
• With embedded or associated proteins & lipids
• Position of many of the proteins is constantly changing
• Formed by polysaccharide side chains of proteins and lipids
• Protects the cell and may help keep other cells as a distance
• Enable cells to recognise one another and to make contact

Question 6

inner face

Answer 6

more unsaturated fatty acids, thus is more fluid ( cis double bonds)

Question 7

outer face

Answer 7

more saturated fatty acids making it more solid or viscous

Question 8

Membrane proteins have two main classes:

Answer 8

• Integral membrane proteins

* Peripheral proteins

Question 9

Integral membrane proteins

Answer 9

Permanently attached to the plasma membrane, thus cannot be removed easily
 Actas
o Anchors 
o Transporters or ion Channels,  
o Enzymes, 
o Receptors
A) single a helix
b)protein consisting of several a helix
c) B barrel consisting of rolled up b- pleated sheet

Question 10

Peripheral Proteins

Answer 10

Anchored to the surface by an amphiphilic α helix
• Attached to the bilayer solely by a covalently bound lipid chain
• Attached via an oligosaccharide linker, to phosphatidylinositol (a.k.a. GPI anchor)
• Attached to integral membrane proteins
• Temporary interactions with biological membranes

Question 11

Aquaporins

Answer 11

• Embedded in the cell membrane that regulate the flow of water.

Question 12

nuclear pores

Answer 12

these complexes regulate the passage of large materials (including large proteins as well as macromolecular complexes such as ribosomes) across the nuclear mem- branes;

Question 13

nuclear lamina

Answer 13

A fibrous network of protein filaments, called the nuclear lamins forms the nuclear lamina, an inner lining for the nuclear envelope. The nuclear lamina supports the inner nuclear membrane and helps organize the nuclear contents.

Question 14

Transport proteins

Answer 14

move ions and small polar molecules through cell membranes.

Question 15

diffusion

Answer 15

the net movement of particles from a region of higher to a region of lower concentration.

Question 16

phospholipids

Answer 16

phospholipids are amphipathic molecules, consisting of two hydrophobic (“water-fearing”) fatty acid chains linked to two of the three carbons of a glycerol molecule. Bonded to the third carbon of the glycerol is a negatively charged, hydrophilic (“water- loving”) phosphate group, which in turn is linked to a polar, hydrophilic organic group.