Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

NA > L13: Lipids, Lipoproteins & Membranes > Flashcards

L13: Lipids, Lipoproteins & Membranes Flashcards

1
Q

What are the Structural Classes for Lipids?

A
  • Glycerolipids
  • Sphingolipids
  • Sterols
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the Functional Classes for Lipids?

A
  • Storage
  • Membrane components
  • Signaling Molecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is Fatty Acid breakdown known as?

A
  • Fatty acid oxidation
  • Beta oxidation
  • Lipid catabolism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where does beta oxidation occur?

A

In the cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the other names for triacylglycerols?

A

Neutral fats or Triglycerides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the structure of Triacylglycerols?

A

Three FA ester-linked to a glycerol backbone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do Triacylglycerols store?

A

Lipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When is C2 of glycerol a pro-chiral center?

A

Chiral if substituents at C1 and C3 are not identical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How are the glycerol and fatty acid chains in a triacylglycerol separated?

A

Hydrolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Under what physiological conditions are fats broken down for energy?

A

Starvation

When glucose levels are low in cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Entry of Glycerol Into Glycolysis

What is the reactants?
What is the product?

A

Reactant: Glycerol
Product: D-Glyceraldehyde

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Catabolism of Fatty Acids - Activation

What must first occur in order for fatty acids to be oxidized?

A

Fatty Acids must be oxidized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Catabolism of Fatty Acids - Activation

What enzyme is involved in the activation of fatty acids?

A

Fatty acyl-CoA synthetase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Catabolism of Fatty Acids - Activation

What is the net reaction of fatty acid activation?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Catabolism of Fatty Acids - Activation

Where does the CoA that is used in the fatty acid activation process come from?

A

CoA is free and in our cytosols

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Catabolism of Fatty Acids - Activation

What is the reactant?

What is the product?

A

Reactant
- Fatty Acid

Product
- Fatty acyl-CoA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Catabolism of Fatty Acids - Transportation

What must occur in order for beta oxidation to take place in the mitochondria?

A

We need to move fatty acids (specifically activated fatty acyl-CoA) into the mitoschondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Catabolism of Fatty Acids - Transportation

What is the goal of Transporting Fatty Acids?

A

Need to move FAs from cytosol to the mitochondrial matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Catabolism of Fatty Acids - Transportation

How are FAs moved from the cytosol to the mitochondrial matrix?

A

By using carnitine as an intermediate carrier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Catabolism of Fatty Acids - Transportation

What is the rate-limiting step in oxidation?

What is this step inhibited by?

A

The formation acyl carnitine is the rate-limiting step in oxidation

Inhibited by malonyl CoA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Catabolism of Fatty Acids - Transportation

What enzymes/transporters are involved in the transportation of Fatty Acids?

Where are these enzymes active?

What are these enzymes inhibited by?

A
  • Carnitine acyltransferase I (cytosol)
  • Carnitine acyltransferase II (mitochondria)
  • Inhibited by malonyl CoA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Catabolism of Fatty Acids - Transportation

What are fatty acids transported into the mitochondria as?

A

As acylcarnitine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Catabolism of Fatty Acids

What are the 3 steps in Fatty acid catabolism - post activation and transportation?

What are the products of each step?

A

1) Beta oxidation of acyl chain -> acetyl-CoA

2) Oxidation of acetyl-CoA -> CO2

3) Electron transfer -> ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Catabolism of Fatty Acids - B oxidation

What is the goal of beta oxidation?

A

Introduce oxygen @ the beta carbon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Catabolism of Fatty Acids - B oxidation

Describe what occurs during beta oxidation

A

1) Clipping the big fatty acid molecule into small components

2) Releases acetyl CoA

3) Releases NRG in the form of reducing equivalents that produce NADH & FADH2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Comparative Energy Yield

How many carbons does glucose have?

How many carbons does palmitoyl-CoA have?

How much ATP does the complete oxidation of glucose yield?

How much ATP does the complete oxidation of palmitoyl-CoA yield?

A

6 Carbons
Glucose: 30-32 ATP
- apx 5 ATP/Carbon

16 Carbons
Palmitoyl-CoA: 106 ATP
- apx 6 ATP/Carbon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Comparative Energy Yield

Why is glucose still our primary energy source?

A

Stored as hydrophilic glycogen
- In most cells can be rapidly utilized

Fats are hydrophobic and stored in separate, specialized cells
- Takes much more time to transport and use as energy source

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Energy Yield

What is the net reaction of the oxidation of Palmitoyl-CoA?

A
29
Q

Energy Yield

What is the net reaction of the Acetyl-CoA produced in the oxidation of Palmitoyl-CoA when it enters the citric acid cycle?

A
30
Q

Energy Yield

What is the total Net reaction of the catabolism of Palmitoyl-CoA?

How much ATP does Palmitoyl-CoA produce after it has went through oxidative phosphorylation?

A

108 ATP - 2 ATP = 106 ATP

31
Q

Unsaturated vs. Saturated Fatty Acids

What are Fats typically made of?

A

Fats are typically made of a long hydrocarbon chain & contains a carboxyl group

32
Q

Unsaturated vs. Saturated Fatty Acids

Describe a saturated fat

A

Only single bonds
- Very compact

33
Q

Unsaturated vs. Saturated Fatty Acids

Describe an unsaturated fat
What does it create?
What for are the bonds in?

A

Contains at least one double bond
- Creates kinks, preventing tight compaction

Usually cis double bonds
- Trans double bonds lead to formation of trans fats

34
Q

Unsaturated vs. Saturated Fatty Acids

Are Saturated or unsaturated fats easier to melt?

A

Unsaturated fats are easier to melt

35
Q

Unsaturated vs. Saturated Fatty Acids

What are the 3 issues that occur in beta oxidation with unsaturated bonds?

A

1) Mono-unsaturated Fatty Acid with one cis double bond
2) Polysaturated FA’s
3) Odd-numbered Fatty Acids

36
Q

Unsaturated vs. Saturated Fatty Acids

What is issue with probelm 1?

A

Need to convert into format that resembles a step in beta-oxidation

37
Q

Unsaturated vs. Saturated Fatty Acids

What is the solution to problem 1?

A

Use an isomerase to convert cis-bind into a trans-bond

  1. Regular beta-oxidation util you hit double bond
  2. Isomerase acts
  3. Continued beta-oxidation
38
Q

Unsaturated vs. Saturated Fatty Acids

What is the issue with problem 2?

A

Polyunsaturated fatty acids have multiple double bonds

39
Q

Unsaturated vs. Saturated Fatty Acids

What is the solution to problem 2?

A

Reduce a double bond to a single bond

  1. Reductase enzyme reduces to one double bond
  2. Isomerase moved double bond to produce beta-oxidation intermediate (double bond between alpha and beta)
40
Q

Unsaturated vs. Saturated Fatty Acids

What is the issue with problem 3?

A

Last round of beta oxidation produced propionyl-CoA (3C molecule)

41
Q

Unsaturated vs. Saturated Fatty Acids

What is the solution to problem 3?

A

Turn it unto succinyl-CoA (a 4C TCA intermediate)

  1. Carboxylate propionyl-CoA using propionyl-CoA carboxylase
    - Carboxylation uses ATP and biotin
  2. Convert D-methulmalonyl-CoA to L using methylmalonyl-CoA mutase
    - The carbonyl/S-CoA and H-atom “swap places”
42
Q

Ketone Bodies and Ketogenesis

Once FAs are catabolized into Acetyl-CoAs

What pathways could they enter?

A

TCA Cycle or Ketogenesis

43
Q

Ketone Bodies and Ketogenesis

Describe Ketone Bodies
- Derivation?
- Purpose?
- When is it made?
- Number of main molecules

A

1) Derived from acetyl-CoA

2) Important fuels transported throughout the body (hydrophilic)

3) Made during starvation

4) 3 Main molecules

44
Q

Ketone Bodies and Ketogenesis

What are the Main 3 Ketone bodies?

A

Acetone

Acetoacetate

beta-Hydroxybutyrate

45
Q

Ketone Bodies and Ketogenesis

What is Ketogenesis?
Where does it take place, what does it use?
When does it take place?

A
  • Generates Ketone bodies
  • Occurs in the liver using acetyl CoA
  • Takes place during starvation
46
Q

Ketone Bodies and Ketogenesis

What occurs during starvation?

A
  • Gluconeogenesis depletes TCA intermediates
  • TCA slows and acetyl CoA builds
  • acetyl-CoA -> acetoacetate
  • KBs are sent to the brain, muscle, heart, and kidneys
47
Q

Ketone Bodies and Ketogenesis

What is the net reaction of Ketogenesis?

What is the enzyme associated with the 4 condensation steps of ketogenesis?

A
48
Q

Ketone Bodies and Ketogenesis

What property makes ketone bodies be able to be transported in the bloodstream from producing organs to the consumer organs that use ketone bodies as fuel?

A

Ketone bodies contain oxygen in higher proportions so they are soluble and can be transported in the bloodstream from producing organs to the consumer organs that use ketone bodies as fuel

49
Q

Ketone Bodies and Ketogenesis

How Does Acetyl-CoA interact with membranes?
What determines this interaction?

A

Acetyl-CoA does not cross membranes because of CoA

50
Q

Beta Oxidation vs. Biosynthesis

Carbon Units

A

Beta: C2

Bio: C2

51
Q

Beta Oxidation vs. Biosynthesis

C2 Product/Donor

A

Beta: Acetyl-CoA

Bio: Malonyl-CoA

52
Q

Beta Oxidation vs. Biosynthesis

Electron Acceptor/Donor

A

Beta: NAD+/FAD

Bio: NADPH

53
Q

Beta Oxidation vs. Biosynthesis

Location

A

Beta: Mitochondria

Bio: Cytosol

54
Q

FA Biosynthesis

Describe Acetyl-CoA in the context of FA Biosynthesis

How does Acetyl-CoA enter cytosol?

Is it exported directly?

A
  • Acetyl-CoA must be transported from the mitochondria into the cytosol (where biosynthesis occurs)
  • Acetyl-CoA cannot be exported directly
55
Q

FA Biosynthesis

How is Acetyl-CoA exported into the cytosol?

How much ATP does the exportation process cost?

What bi-product does this process produce?

A
  • Lysed to Acetyl-CoA (C2)
  • The remains (C3 or C4) are re-imported
  • 2 ATP per acetyl-CoA
  • Generates cytosolic NADPH
56
Q

FA Biosynthesis

What is the goal of the Acetyl Group Shuttle?

A

Transport an acetyl CoA equivalent from the matrix to the cytosol

57
Q

Precursor for FA Biosynthesis

What are the 6 steps in transporting Acetyl-CoA into the cytosol?

A
57
Q

FA Biosynthesis

What are FAs synthesized from?

What is the energy source for this synthesization?

A
  • FAs are synthesized form Malonyl-CoA, not directly from acetyl-CoA
  • Acetyl-CoA carboxylase forms malonyl-CoA using ATP
57
Q

FA Biosynthesis

What is the commitment step in FA synthesis?

A

Formation of malonyl-CoA

58
Q

FA Biosynthesis

What is the formation of malonyl-CoA inhibited by?

A

Glucagon, epinephrine, palmitoyl-CoA

59
Q

FA Biosynthesis

What is the formation of malonyl-CoA activated by?

A

Citrate

60
Q

FA Biosynthesis

What is the precursor step to FA Synthesis?

What is the 4-Step Sequence of FA Synthesis?

What enzyme is involved in FA synthesis?

What happens after the 4 step sequence of FA synthesis?

A

Precursor: Fatty Acid Synthase is loaded with acetyl-CoA and the ACP subunit with malonyl-CoA

4 Steps of Synthesis
1) Condensation
2) Reduction using NADPH
3) Dehydration
4) Reduction using NADPH

FA Synthase is involved in FA synthesis
- Very complex, has 7 subunits

Post Synthesis
1) Growing chain moves to KS
2) ACP is reloaded with malonyl-CoA for the 2nd round

After 7 cycles , a palmitate-specific thioesterase cleaves the completed fatty acid from FA synthase

61
Q

FA Biosynthesis

What is the NET reaction of the biosynthesis of palmitate?

A
62
Q

FA Biosynthesis

How are fatty acid synthesis and breakdown regulated and coordinated?

How does this coordination occur?

A

The opposing process must be coordinated so only one occurs at a time

  • Coordination occurs through malonyl CoA
    as it initiates FA synthesis and inhibits beta oxidation
63
Q

TAG and Glycerophospholipids Synth

What is the precursor for both?

A

Phosphatic acid
- Made from L-G3P
- 2 FAs attached with phosphate group

64
Q

TAG and Glycerophospholipids Synth

What are the 2 steps in Triacyl-Glycerol Synth?

A

1) Replace phosphate group with OH
2) Replace OH group with FA

65
Q

TAG and Glycerophospholipids Synth

What are the 2 methods for steps in Glycerophospholipids Synth?

A

Method 1: Activation of phosphatic acid

Method 2: Activation of the head group

66
Q
A

NA (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions