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Bio 131 > Exam 1: Lipids, membranes, and cells > Flashcards

Exam 1: Lipids, membranes, and cells Flashcards

1
Q

What is the polarity of lipids?

A

Non-polar

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2
Q

What are the three types of lipids?

A

Fats, Steroids, Phospholipids

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3
Q

How do lipids form?

A

Dehydration reactions (remove a water)

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4
Q

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

A

A simple lipid

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

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5
Q

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

A

Unsaturated fatty acids have double bonds

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6
Q

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

A

There is a kink

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7
Q

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

A

Saturated fatty acids

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8
Q

What is a glycerol?

A

3 carbon chain; each carbon bonded to a hydroxyl

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9
Q

What is the structure of a fat?

A

A glycerol linked to three fatty acids

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10
Q

How are fats formed?

A

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

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11
Q

What is the structure of steroids?

A

Four carbon rings with a hydroxyl group

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12
Q

What are steroids derived from?

A

Cholesterol

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13
Q

Why are steroids slightly soluble in water?

A

They have a hydroxyl group

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14
Q

What are the three components of a phospholipid?

A

Phosphate group, glycerol, two fatty acids

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15
Q

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

A

Phosphate group

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16
Q

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

A

Fatty acid

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17
Q

What are the two main components of the cell membrane?

A

Steroids and phospholipids

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18
Q

What are the three mechanisms of membrane transport?

A
  1. Diffusion
  2. Facilitated diffusion
  3. Active transport
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19
Q

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

A
  1. Small, nonpolar molecules (O2, CO2)
  2. Small, uncharged, polar molecules (H2O, glycerol)
  3. Large, uncharged, polar molecules (glucose)
  4. Ions (Cl-)
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20
Q

What are four factors that affect membrane permeability?

A
  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
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21
Q

What is diffusion?

A

Molecules moving from high concentration to low concentration

22
Q

Does diffusion move along or against the concentration gradient?

A

Along

23
Q

What happens when equilibrium is reached?

A

Still movement of molecules, but no net change

24
Q

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

A

Increases

25
Q

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

A

Decreases

26
Q

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

A

Increases

27
Q

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

A

Increases

28
Q

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

A

Increases

29
Q

What is osmosis?

A

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

30
Q

Water moves from regions of _____ to regions ______

A

low solute concentration to high solute concentration

31
Q

What is meant by isotonic?

A

Equal water and solute concentrations on either side of the membrane

32
Q

What is meant by hypertonic?

A

Solute concentration is higher on one side of the membrane

33
Q

What is meant by hypotonic?

A

Solute concentration is lower on one side of the membrane

34
Q

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

A

Water flows to the inside causing the vesicle to burst

35
Q

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

A

Water flows to the outside causing the vesicle to shrink

36
Q

Does passive transport require ATP? Active transport?

A

No. Yes.

37
Q

Where are peripheral membrane proteins located?

A

One side of the membrane

38
Q

Where are integral membrane proteins located?

A

In the membrane

39
Q

What is another name for integral proteins?

A

Transmembrane proteins

40
Q

What type of protein are transport proteins?

A

Integral proteins

41
Q

What are the three classes of transport proteins?

A
  1. Channels
  2. Carrier proteins
  3. Pumps
42
Q

How do ions cross the membrane?

A

Ion channels or pumps

43
Q

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

A

Electrochemical gradients

44
Q

What is an electrochemical gradient?

A

A combination of a concentration and charge gradient

45
Q

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

A

Aquaporin

46
Q

What are gated channels?

A

Open or close in response to a signal

47
Q

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

A

The passive transport of substances that would not otherwise cross the membrane

Can occur through channels or transporter/carrier proteins

48
Q

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

A
  1. Unbound protein
  2. Desired molecule binds
  3. Protein undergoes conformational change
  4. Release of desired molecule
49
Q

What is the sodium-potassium pump an example of?

A

Active transport

50
Q

What are the 8 steps of the sodium potassium pump?

A
  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
51
Q

What do ATP driven ion pumps generate?

A

Ion electrochemical gradients

52
Q

How does secondary active transport/cotransport work?

A

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

Bio 131 (25 decks)

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