Biochem Chapter 7

Question 1

Lipid Bilayer

Answer 1

double layer with proteins embedded throughout

Question 2

Why is it called the Fluid Mosaic Model?

Answer 2

Fluid because the proteins are moving around in the bilayer and the bilayer (phospholipids) are flexible. Mosaic because there are a bunch of macromolecules making up a membrane

Question 3

Why do proteins move slowly in the fluid environment of the membrane

Answer 3

proteins are larger than lipid molecules

Question 4

Is the membrane symmetrical? Why or why not

Answer 4

The membrane is very asymmetrical. Proteins on one half of the lipid bilayer differ in function from those that make up the other half of the bilayer

Question 5

What are the three components of the plasma membrane?

Answer 5

Phospholipids, Membrane Proteins, Glycolipids and Glycoproteins

Question 6

What are the dominant lipids found in the membrane?

Answer 6

Phospholipids

Question 7

Parts of the phospholipid molecule

Answer 7

Fatty acids/tail/polar region, polar region/head which includes a glycerol, phosphate group, and polar alcohol coline

Question 8

when do phospholipids form a bilayer? Why?

Answer 8

when added to an aqueous solution. The non-polar, hydrophobic fatty acids aggregate together while the polar, hydrophilic heads associate with water. This arrangement is favoured because they represent the lowest energy state, and therefore are more likely than any other arrangement to occur.

Question 9

What major factors are fluidity influenced by

Answer 9

Composition and Temperature

Question 10

Do saturated fats pack tighter or looser?

Answer 10

Tighter because there are no kinks and bends

Question 11

Do unsaturated fats pack tighter or looser?

Answer 11

Looser because they have double bonds so their kinks and bends take up space.

Question 12

Membranes remain in a ____ ____ over a variety of temperatures

Answer 12

fluid state

Question 13

If the temperature drops low enough…

Answer 13

molecules will become densely packed forming a highly viscous gel

Question 14

The fluidity of a membrane is related to how many lipids are _____

Answer 14

unsaturated. the more unsaturated, the lower its gelling temperature

Question 15

Sterols like _____ help to _____

Answer 15

cholesterol, stabilize the membrane

Question 16

At high temperatures, cholesterol

Answer 16

reduces fluidity by restraining the movement

Question 17

At low temperatures, sterols

Answer 17

increase fluidity by occupying the space between lipid molecules (preventing tight packing)

Question 18

What is the function of transport of proteins

Answer 18

help move substances across the membrane that cannot move freely through

Question 19

What acts as enzymes for important chemical reactions such as cellular respiration

Answer 19

enzymatic activity

Question 20

Signal Transduction

Answer 20

may bind to chemicals such as hormones, which triggers changes on inner surface of the membrane

Question 21

Cell to Cell Recognition

Answer 21

recognizes markers on other cells

Question 22

joins two cells together

Answer 22

intercellular joining

Question 23

If proteins are embedded in the lipid bilayer they are called

Answer 23

integral membrane proteins (IMP)

Question 24

If proteins are positioned on the surface of a membrane they are called

Answer 24

Peripheral membrane proteins (PMP)

Question 25

A lipid and a carb are called

Answer 25

glycolipids

Question 26

A carb and a protein are called

Answer 26

glycoproteins. They face the exterior of the cell and often play a role in cell to cell recognition