Exam 1: Lipids, membranes, and cells

Question 1

What is the polarity of lipids?

Answer 1

Non-polar

Question 2

What are the three types of lipids?

Answer 2

Fats, Steroids, Phospholipids

Question 3

How do lipids form?

Answer 3

Dehydration reactions (remove a water)

Question 4

What is a fatty acid? What does it look like?

Answer 4

A simple lipid

Hydrocarbon chain bonded to polar carboxyl functional group (-COOH)

Question 5

What is the difference between a saturated fatty acid and an unsaturated fatty acid?

Answer 5

Unsaturated fatty acids have double bonds

Question 6

What is the effect of a double bond on the structure of a fatty acid?

Answer 6

There is a kink

Question 7

Do saturated fatty acids or unsaturated fatty acids have a higher boiling point?

Answer 7

Saturated fatty acids

Question 8

What is a glycerol?

Answer 8

3 carbon chain; each carbon bonded to a hydroxyl

Question 9

What is the structure of a fat?

Answer 9

A glycerol linked to three fatty acids

Question 10

How are fats formed?

Answer 10

Ester linkages; dehydration synthesis b/t hydroxyl group of GLYCEROL and carboxyl group of free FATTY ACID

Question 11

What is the structure of steroids?

Answer 11

Four carbon rings with a hydroxyl group

Question 12

What are steroids derived from?

Answer 12

Cholesterol

Question 13

Why are steroids slightly soluble in water?

Answer 13

They have a hydroxyl group

Question 14

What are the three components of a phospholipid?

Answer 14

Phosphate group, glycerol, two fatty acids

Question 15

What makes up the polar (hydrophilic) head of a phospholipid?

Answer 15

Phosphate group

Question 16

What makes up the nonpolar (hydrophobic) tail of a phospholipid?

Answer 16

Fatty acid

Question 17

What are the two main components of the cell membrane?

Answer 17

Steroids and phospholipids

Question 18

What are the three mechanisms of membrane transport?

Answer 18

1. Diffusion
2. Facilitated diffusion
3. Active transport

Question 19

Rank the four types of molecules in order of decreasing membrane permeability:

Answer 19

1. Small, nonpolar molecules (O2, CO2)
2. Small, uncharged, polar molecules (H2O, glycerol)
3. Large, uncharged, polar molecules (glucose)
4. Ions (Cl-)

Question 20

What are four factors that affect membrane permeability?

Answer 20

1. Number of double bonds on the fatty acids
2. Length of the tail
3. Number of cholesterol molecules (more cholesterol = less permeable
4. Temperature

Question 21

What is diffusion?

Answer 21

Molecules moving from high concentration to low concentration

Question 22

Does diffusion move along or against the concentration gradient?

Answer 22

Along

Question 23

What happens when equilibrium is reached?

Answer 23

Still movement of molecules, but no net change

Question 24

If temperature is increased, what happens to diffusion rate through a membrane?

Answer 24

Increases

Question 25

If molecular weight is increased, what happens to diffusion rate through a membrane?

Answer 25

Decreases

Question 26

If the steepness of the concentration gradient increases, what happens to diffusion rate through a membrane?

Answer 26

Increases

Question 27

If the membrane surface area increases (more gaps/spread out), what happens to diffusion rate through a membrane?

Answer 27

Increases

Question 28

If membrane permeability increases, what happens to diffusion rate through a membrane?

Answer 28

Increases

Question 29

What is osmosis?

Answer 29

Special case of diffusion in which water moves across selectively permeable membrane; can occur through lipid bilayer or aquaporins

Question 30

Water moves from regions of _____ to regions ______

Answer 30

low solute concentration to high solute concentration

Question 31

What is meant by isotonic?

Answer 31

Equal water and solute concentrations on either side of the membrane

Question 32

What is meant by hypertonic?

Answer 32

Solute concentration is higher on one side of the membrane

Question 33

What is meant by hypotonic?

Answer 33

Solute concentration is lower on one side of the membrane

Question 34

If the inside solution is hypertonic to the outside, what happens?

Answer 34

Water flows to the inside causing the vesicle to burst

Question 35

If the inside solution is hypotonic to the outside what happens?

Answer 35

Water flows to the outside causing the vesicle to shrink

Question 36

Does passive transport require ATP? Active transport?

Answer 36

No. Yes.

Question 37

Where are peripheral membrane proteins located?

Answer 37

One side of the membrane

Question 38

Where are integral membrane proteins located?

Answer 38

In the membrane

Question 39

What is another name for integral proteins?

Answer 39

Transmembrane proteins

Question 40

What type of protein are transport proteins?

Answer 40

Integral proteins

Question 41

What are the three classes of transport proteins?

Answer 41

1. Channels 2. Carrier proteins 3. Pumps

Question 42

How do ions cross the membrane?

Answer 42

Ion channels or pumps

Question 43

What occurs when ions build up on one side of a plasma membrane?

Answer 43

Electrochemical gradients

Question 44

What is an electrochemical gradient?

Answer 44

A combination of a concentration and charge gradient

Question 45

What channel protein facilitates the movement of water through a membrane?

Answer 45

Aquaporin

Question 46

What are gated channels?

Answer 46

Open or close in response to a signal

Question 47

What is facilitated diffusion? How can it occur? (2 ways)

Answer 47

The passive transport of substances that would not otherwise cross the membrane Can occur through channels or transporter/carrier proteins

Question 48

What are the steps for facilitated diffusion via transporter/carrier proteins? (like GLUT-1)

Answer 48

1. Unbound protein 2. Desired molecule binds 3. Protein undergoes conformational change 4. Release of desired molecule

Question 49

What is the sodium-potassium pump an example of?

Answer 49

Active transport

Question 50

What are the 8 steps of the sodium potassium pump?

Answer 50

1. Unbound pump 2. 3 Sodium bind 3. Pump undergoes shape change as P from ATP binds 4. 3 Sodium released outside 5. Unbound pump 6. 2 Potassium bind 7. P releases causing shape change 8. 2 Potassium released

Question 51

What do ATP driven ion pumps generate?

Answer 51

Ion electrochemical gradients

Question 52

How does secondary active transport/cotransport work?

Answer 52

Pumps move materials against concentration gradient => sets up electrochemical gradient => electrochemical gradient provides potential energy to power movement of another molecule against its particular gradient