Chapter 5: Cell Membrane

Question 1

Fluid mosaic model

Answer 1

Is a model that describes a phospholipid bilayer in which proteins can move about (float in the lipid “lake”)

Question 2

What are the 3 major functions of fluid mosaic model?

Answer 2

1. Move materials through the membrane
2. involved in intercellular recognition and adhesion
3. receive chemical signals from the cell’s external environment

Question 3

What does carbohydrate attach to in the fluid mosaic membrane?

Answer 3

They attach to either lipid or protein molecules

Question 4

Lipid rafts

Answer 4

form from glycolipoprotein lipid microdomains and include more cholesterol (acts like a glue that holds it together and stiffens it)

Question 5

cholesterol

Answer 5

Is a steroid and is found in the membranes of animals and some bacteria.

Question 6

What is cholesterol made of?

Answer 6

It is made of multiple linked rings and a hydroxyl group that interacts with hydrophilic heads of phospholipids

Question 7

Phospholipids may differ in what?

Answer 7

1. Hydrocarbon chain length
2. degree of saturation
3. kinds of polar groups present

Question 8

What are the 2 important factors in membrane fluidity?

Answer 8

1. lipid composition and proteins

Question 9

Lipid composition

Answer 9

Are types of hydrocarbon tails (Unsaturated or saturated) can increase or decrease fluidity

Question 10

What are the 2 types of membrane proteins?

Answer 10

1. peripheral membrane protein

2. Intergral membrane proteins

Question 11

Peripheral Membrane Protein

Answer 11

They lack hydrophobic groups and are not embedded in the bilayer

Question 12

Intergral Membrane Proteins

Answer 12

They are at least partly embedded in the phospholipid bilayer that contain both hydrophilic and hydrophobic groups. Hydrophobic groups anchor the protein in the membrane

Question 13

Transmembrane Protein

Answer 13

An intergral membrane protein that extends all the way through the phospholipid bilayer and protrudes on both sides are always oriented the same way

Question 14

glycolipid

Answer 14

They consists of a carbohydrate covalently bonded to a lipid

Question 15

Glycoprotein

Answer 15

They consists of 1 or more short carbohydrate chains covalently bonded to a protein

Question 16

Proteoglycan

Answer 16

A protein with even more carbohydrate molecules attached to it

Question 17

Passive transport

Answer 17

Does not require metabolic energy

Question 18

Active transport

Answer 18

Requires input of metabolic energy because they involve the movement of a substance against their concentration gradients

Question 19

Diffusion

Answer 19

is the process of random movement toward a state of equilibrium

Question 20

Simple diffusion

Answer 20

When molecules that are hydrophobic and soluble in lipids can pass through the membrane

Question 21

What does diffusion do?

Answer 21

1. They have molecules from an area of higher concentration to one of lower concentration
2. can occur in any medium (liquid, solid, gas)
3. Doesn’t require a semipermeable membrane

Question 22

Osmosis

Answer 22

The net movement of a solvent across a selective permeable membrane into a region of higher solute concentration

Question 23

What does osmosis do?

Answer 23

1. Can only occur in liquid
2. requires a semipermeable membrane
3. movement seeks to equalize solvent concentration (although it doesn’t achieve it)

Question 24

What are the 3 terms used to compare solute concentrations of 2 solutions separated by a membrane?

Answer 24

1. Hypertonic
2. Isotonic
3. Hypotonic

Question 25

Hypertonic

Answer 25

The solution has a higher solute concentration than the other solution

Question 26

Isotonic

Answer 26

The solution has an equal solute concentration

Question 27

Hypotonic

Answer 27

The solution has lower solute concentration than other solution

Question 28

Channel proteins

Answer 28

Are integral membrane proteins that form channels across the membrane (speeds of diffusion)