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Bio 131 Exam 1 > Wk2 Lecture 1 Ch 6 > Flashcards

Wk2 Lecture 1 Ch 6 Flashcards

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1
Q

What is a lipid?

A

Any organic (carbon-containing) substance that does not dissolve in water, but dissolves well in nonpolar organic solvents.

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2
Q

What is a hydrocarbon?

A

Molecules that contain only carbon and hydrogen

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3
Q

Why are hydrocarbons nonpolar?

A

Electrons are shared equally in C and H bonds b/c of similar electronegativities

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4
Q

Why are lipids mostly hydrophobic?

A

They have a significant hydrocarbon component

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5
Q

What does saturated mean?

A

Refers to lipids; hydrocarbon chains that consist of only single bonds b/t carbons

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6
Q

What does unsaturated mean?

A

Refers to lipids; hydrocarbon chains that consist of one or more double bonds b/t carbons

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7
Q

Saturated lipid structure

A

Straight

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8
Q

Unsaturated lipid structure

A

Bent

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9
Q

Saturated lipid physical state

A

Straight => tightly packed => solid

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10
Q

Unsaturated lipid physical state

A

Bent => fewer interactions/more space => liquid

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11
Q

Saturated lipid melting point

A

Relatively high => solid at room temp

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12
Q

Unsaturated lipid melting point

A

Relatively low => liquid at room temp

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13
Q

What are lipids with extremely long saturated hydrocarbon chains called?

A

Waxes

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14
Q

What are highly unsaturated lipids at room temp called?

A

Oils

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15
Q

What are the main types of lipids found in cells?

A
  1. Steroids
  2. Fats
  3. Phospholipids
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16
Q

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

A

A simple lipid; hydrocarbon chain bonded to polar carboxyl functional group (-COOH)

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17
Q

What does a steroid look like?

A

4 hydrocarbon rings with hydroxyl group

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18
Q

What are steroids derived from?

A

Cholesterol

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19
Q

Tiny differences in structure can lead to

A

Very different and specific biological properties

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20
Q

Steroid solubility in water?

A

Usually insoluble, BUT have hydroxyl group

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21
Q

What is a glycerol?

A

3 carbons chain; each carbon bonded to a hydroxyl

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22
Q

What does a fat look like?

A

3 fatty acids linked by ester linkages to glycerol (3 carbon molecule)

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23
Q

What are fats also known as (2)?

A

Triacylglycerols or Triglycerides

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24
Q

How are fats formed?

A

Dehydration (synthesis) reaction b/t hydroxyl group of GLYCEROL and carboxyl group of free FATTY ACID => ester linkage

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25
Q

What does a phospholipid look like?

A

Glycerol linked to a phosphate group and 2 hydrocarbon chains (isoprenoids or fatty acids [ester linkage]); phosphate group is bonded to a small organic molecule that is charged/polar.

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26
Q

Phospholipids w/ fatty acid tails are found in which domain(s)?

A

Bacteria and Eukarya

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27
Q

Phospholipids w/ isoprenoid tails are found in which domain(s)?

A

Archaea

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28
Q

Most prominent function of lipids?

A

Role in cell membranes

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29
Q

What are the primary components of the cell membrane?

A

Phospholipids and Steroids

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30
Q

Describe phospholipid head and tail

A

The head is polar/hydrophilic b/c of the negatively charged phosphate group attached to a polar group. The tail is nonpolar/hydrophilic.

31
Q

Substances that contain both hydrophilic and hydrophobic regions are…

A

Amphipathic

32
Q

What do amphipathic lipids do when placed in water?

A

They do not dissolve–they assume either a micelle or lipid bilayer structure

33
Q

What is a micelle?

A

Spherical aggregates created when hydrophilic heads of a set of lipids face outward and interact w/ water, while the hydrophobic tails interact w/ each other in the interior

34
Q

What is a lipid bilayer?

A

Created when lipid molecules align in paired sheets. Hydrophilic heads face surrounding solution while hydrophobic tails face one another inside bilayer.

35
Q

What do micelles form from?

A

Free fatty acids or other simple saturated amphipathic lipids

36
Q

What do bilayers form from? What are they called?

A

Phospholipids, which have bulkier nonpolar regions consisting of two hydrocarbon tails; Phospholipid bilayer

37
Q

How do lipid bilayers (and micelles) form in water?

A

Spontaneously; no energy required b/c it is favorable

38
Q

What is permeability?

A

A structure’s tendency to allow a given substance to pass through it

39
Q

What is selective permeability?

A

Some substances cross a membrane more easily than other substances do; molecular discrimination

40
Q

Rank in terms of permeability:
-Large, uncharged polar molecules
-Small, uncharged polar molecules
-Small, nonpolar molecules
-Charged ions

Give examples

A
  1. Small, nonpolar molecules (O2, CO2, N2)
  2. Small, uncharged polar molecules (H2O, glycerol)
  3. Large, uncharged polar molecules (Glucose, sucrose)
  4. Charged ions (Cl-, K+, Na+)

1 and 2 can still diffuse

41
Q

List 4 factors that affect membrane permeability/fluidity

A
  1. Number of double bonds b/t carbons in the phospholipid tail
  2. Length of tail
  3. Number of cholesterol molecules in membrane
  4. Temperature
42
Q

Explain how tail length and saturated v unsaturated affects membrane permeability/fluidity

A

More unsaturated and shorter tail length => higher permeability and fluidity

Less unsaturated and longer tail length => lower permeability and fluidity

Longer hydrocarbon tails have more interactions (denser membrane) and saturated fatty acids have straight hydrocarbon tails that pack together tightly, leaving few gaps

43
Q

Explain how temperature affects membrane permeability/fluidity

A

Higher temperature => higher particle motion => higher permeability

Lower temp slows movement of hydrocarbon tails, allowing more interactions => more dense membrane

44
Q

Explain how presence of cholesterol affects membrane permeability/fluidity

A

More cholesterol => less permeable

Less cholesterol => more permeable

45
Q

What is diffusion?

A

Molecules move through concentration gradient (high to low concentration); used in reference to movement of molecules across plasma membrane

46
Q

What is passive transport?

A

Substances diffusing across a membrane w/o energy

47
Q

What happens at equilibrium after diffusion?

A

Solutes continue to move back and forth across the membrane at equal rates due to constant random motion; no net movement of solutes b/c they are equally likely to move in any direction

48
Q

What is osmosis?

A

Diffusion of water across selectively permeable membrane from lower solute concentration (high water) to higher solute concentration (low water); can occur through lipid bilayer or aquaporins

49
Q

When does osmosis occur?

A

-Solutions are separated by selectively permeable membrane
-Solutes cannot pass through the membrane

50
Q

What is isotonic?

A

Equal water and solute concentrations on either side of the membrane

51
Q

What is hypertonic?

A

Solute concentration higher (water lower) on one side of the membrane

52
Q

What is hypotonic?

A

Solute concentration is lower (water higher) on one side of the membrane

53
Q

What is a integral/transmembrane protein?

A

A membrane protein that spans the entire lipid bilayer

54
Q

What is a peripheral membrane protein?

A

Any membrane protein that does not span the entire lipid bilayer but instead binds to only one side of the bilayer (exterior or interior)

55
Q

What are transport proteins?

A

Integral/transmembrane proteins that transport molecules

56
Q

What are three broad classes of transport proteins?

A
  1. Channels
  2. Carrier/transporters
  3. Pumps
57
Q

What are channel proteins?

A

Integral/transmembrane protein that forms an open passageway for the direct diffusion of certain ions/molecules across the membrane

58
Q

What is facilitated diffusion?

A

Passive transport of substances that would not otherwise cross the membrane

59
Q

Through which ways can facilitated diffusion occur?

A

-Channels
-Carrier proteins/transporters

60
Q

How do ions cross membranes?

A

Ion channels

61
Q

What is an ion channel?

A

Channel protein that allows certain ions to diffuse across plasma membrane down an electrochemical gradient

62
Q

What is an electrochemical gradient?

A

Combined effect of ion’s concentration and electrical/charge gradient across membrane that affects diffusion of ions; charge gradient moves in the direction that neutralizes net charges on both sides (i.e. areas of like charge to unlike charge)

63
Q

What is an aquaporin?

A

Channel protein that facilitates movement of water (osmosis) across a plasma membrane)

64
Q

What are gated channels?

A

Channel protein that open/closes in response to a signal, carefully controlling flow of ions/small molecules

65
Q

Examples of gated channels

A

Aquaporin and many ion channels

66
Q

What are carrier proteins/transporters?

A

Integral/transmembrane protein that facilitates diffusion of small molecules across a membrane through conformational change.

67
Q

Example of carrier protein?

A

Glucose transporter

68
Q

What is active transport?

A

The movement of ions/molecules in a single direction against a gradient; requires energy in the form of ATP

69
Q

What are pumps?

A

Any membrane protein that uses energy to provide active transport of molecules across the membrane

70
Q

How does ATP provide energy for active transport?

A

By transferring a phosphate group to a pump

71
Q

What is the sodium-potassium pump?

A

A pump that uses ATP to transport NA+ and K+ against their concentration gradients; 3 sodium
out for every 2 potassium in. Ex: electrical and concentration gradients of a membrane tend to drive sodium into and potassium out of cell (b/c interior of cell is negative and has less sodium/more potassium), but active transport works against these gradients

72
Q

What do ATP driven ion pumps generate?

A

Ion electrochemical gradients

73
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

74
Q

What are the three mechanisms of membrane transport?

A
  1. Diffusion
  2. Facilitated Diffusion
  3. Active Transport

Bio 131 Exam 1 (6 decks)

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