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

Wk2 Lecture 1 Ch 6 Flashcards

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
What does a phospholipid look like?
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.
26
Phospholipids w/ fatty acid tails are found in which domain(s)?
Bacteria and Eukarya
27
Phospholipids w/ isoprenoid tails are found in which domain(s)?
Archaea
28
Most prominent function of lipids?
Role in cell membranes
29
What are the primary components of the cell membrane?
Phospholipids and Steroids
30
Describe phospholipid head and tail
The head is polar/hydrophilic b/c of the negatively charged phosphate group attached to a polar group. The tail is nonpolar/hydrophilic.
31
Substances that contain both hydrophilic and hydrophobic regions are...
Amphipathic
32
What do amphipathic lipids do when placed in water?
They do not dissolve--they assume either a micelle or lipid bilayer structure
33
What is a micelle?
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
What is a lipid bilayer?
Created when lipid molecules align in paired sheets. Hydrophilic heads face surrounding solution while hydrophobic tails face one another inside bilayer.
35
What do micelles form from?
Free fatty acids or other simple saturated amphipathic lipids
36
What do bilayers form from? What are they called?
Phospholipids, which have bulkier nonpolar regions consisting of two hydrocarbon tails; Phospholipid bilayer
37
How do lipid bilayers (and micelles) form in water?
Spontaneously; no energy required b/c it is favorable
38
What is permeability?
A structure's tendency to allow a given substance to pass through it
39
What is selective permeability?
Some substances cross a membrane more easily than other substances do; molecular discrimination
40
Rank in terms of permeability: -Large, uncharged polar molecules -Small, uncharged polar molecules -Small, nonpolar molecules -Charged ions Give examples
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
List 4 factors that affect membrane permeability/fluidity
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
Explain how tail length and saturated v unsaturated affects membrane permeability/fluidity
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
Explain how temperature affects membrane permeability/fluidity
Higher temperature => higher particle motion => higher permeability Lower temp slows movement of hydrocarbon tails, allowing more interactions => more dense membrane
44
Explain how presence of cholesterol affects membrane permeability/fluidity
More cholesterol => less permeable Less cholesterol => more permeable
45
What is diffusion?
Molecules move through concentration gradient (high to low concentration); used in reference to movement of molecules across plasma membrane
46
What is passive transport?
Substances diffusing across a membrane w/o energy
47
What happens at equilibrium after diffusion?
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
What is osmosis?
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
When does osmosis occur?
-Solutions are separated by selectively permeable membrane -Solutes cannot pass through the membrane
50
What is isotonic?
Equal water and solute concentrations on either side of the membrane
51
What is hypertonic?
Solute concentration higher (water lower) on one side of the membrane
52
What is hypotonic?
Solute concentration is lower (water higher) on one side of the membrane
53
What is a integral/transmembrane protein?
A membrane protein that spans the entire lipid bilayer
54
What is a peripheral membrane protein?
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
What are transport proteins?
Integral/transmembrane proteins that transport molecules
56
What are three broad classes of transport proteins?
1. Channels 2. Carrier/transporters 3. Pumps
57
What are channel proteins?
Integral/transmembrane protein that forms an open passageway for the direct diffusion of certain ions/molecules across the membrane
58
What is facilitated diffusion?
Passive transport of substances that would not otherwise cross the membrane
59
Through which ways can facilitated diffusion occur?
-Channels -Carrier proteins/transporters
60
How do ions cross membranes?
Ion channels
61
What is an ion channel?
Channel protein that allows certain ions to diffuse across plasma membrane down an electrochemical gradient
62
What is an electrochemical gradient?
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
What is an aquaporin?
Channel protein that facilitates movement of water (osmosis) across a plasma membrane)
64
What are gated channels?
Channel protein that open/closes in response to a signal, carefully controlling flow of ions/small molecules
65
Examples of gated channels
Aquaporin and many ion channels
66
What are carrier proteins/transporters?
Integral/transmembrane protein that facilitates diffusion of small molecules across a membrane through conformational change.
67
Example of carrier protein?
Glucose transporter
68
What is active transport?
The movement of ions/molecules in a single direction against a gradient; requires energy in the form of ATP
69
What are pumps?
Any membrane protein that uses energy to provide active transport of molecules across the membrane
70
How does ATP provide energy for active transport?
By transferring a phosphate group to a pump
71
What is the sodium-potassium pump?
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
What do ATP driven ion pumps generate?
Ion electrochemical gradients
73
How does secondary active transport/cotransport work?
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
What are the three mechanisms of membrane transport?
1. Diffusion 2. Facilitated Diffusion 3. Active Transport

Bio 131 Exam 1 (6 decks)

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