MCM - Lipid Anabolism Flashcards Preview

Biochemistry > MCM - Lipid Anabolism > Flashcards

Flashcards in MCM - Lipid Anabolism Deck (59):
1

What are the Functions of Lipids (4)

1. Fuel Stores; Triacyl Glyverols
2. Structural Components; plasma membranes
3. Signaling Molecules; Prostaglandins
4. "Other;" Provide insulation, generate heat, fat digestion

2

What is the most efficient way to store energy

Triacylglycerols

3

Why are Triacylgrlycerols able to pack tighter

Saturation and tight packing with hydrophobic interations

4

What is the major Carbon source for Fatty Acid Synthesis

Carbohydrates

5

In which organ does Fatty Acid Synthesis mainly Occur

The Liver

6

Where does Fatty Acid Synthesis Occur other than the liver

adipose tissue, the brain, kidneys, lactating mammary glands

7

What are the two precursors for Fatty Acid Synthesis

Acetyl-CoA and Malonyl-CoA

8

What are the three phases of Fatty Acid Synthesis

1. Cytosolic Entry of Acetyl-CoA
2. Generation of Malonyl-CoA
3. Fatty Acid Formation

9

First Step of Fatty Acid Synthesis

Acetyl-CoA and Oxaloacetate Condensation Reaction to form Citrate

10

Where does the Citrate that is formed go

Citrate is shuttled out of the Mitochondria into the cytoplasm

11

What happens to the citrate once in the cytoplasm

ATP Citrate Lyase takes citrate to Oxaloacetate and Acetyl CoA

12

What inhibits ATP Citrate Lyase

PUFA and Leptin

13

What Activates ATP Citrate Lyase

Glucose and Insulin and Phosphorylation

14

Where does the Oxaloacetate go once separated from Citrate

Malate goes back into the mitochondrial matrix or gets turned into Pyruvate by Malic Enzyme

15

What is the Second Step of Fatty Acid Synthesis

Making Malonyl-CoA

16

How do you make Malonyl-CoA

Acetyl-CoA to Malonyl-CoA via Acetyl CoA Carboxylase with ATP; the rate limiting step

17

What inhibits Acetyl-CoA Carboxylase

Glucagon, Epinephrine, High [AMP], Palmitate, PUFA

18

What activates Acetyl-CoA Carboxylase

Citrate and Insulin

19

How does Acetyl-CoA Carboxylase add a carbon onto Acetyl-CoA

CO2 is used

20

What is the Inactive Form of Acetyl-CoA Carboxylase

Dimeric

21

What is the Active form Acetyl-CoA Carboxylase

Polymeric

22

Malonyl-CoA Uses (3)

1. Substrate for Fatty Acid Synthesis
2. Inhibits Carnitine Acyltransferase; the rate limiting step in Beta-Oxidation
3. Prevents FA Synthesis and Degradation from occurring simultaneously

23

What is the Third Phase of Fatty Acid Synthesis

Chain Formation

24

What is the enzyme that is used to grow the Fatty Acid Chain

Fatty Acid Synthase; the rate limiting step of Phase 3

25

What is the makeup of Fatty Acid Synthase

7 enzyme activities and an acyl carrier protein; kind of like an arm

26

How is the Fatty Acid Chain grown; first step

Starts with Acetyl-CoA on the cysteine side and Malonyl-CoA on the pantothenic side; they go through a condensation reaction and make a 4 carbon chain

27

How is the Fatty Acid Chain grown; second step

The 4 Carbon group is Reduced

28

How is the Fatty Acid Chain Grown; Third Step

The 4 Carbon group is Dehydrated

29

How is the Fatty Acid Chain Grown, Fourth Step

The 4 Carbon Group is Reduced

30

How is the Fatty Acid Chain Grown, Cyclic Step

Malonyl-CoA is added to the pantothenic side and steps through 1-4 are repeated (6-7 times depending on size fo FA)

31

What are the 3 regulation points of Fatty Acid Synthesis

1. ATP Citrate Lyase; Phase 1
2. ACC (Acetyl CoA Carboxylase); Phase 2
3. Fatty Acid Synthase; Phase 3

32

What is the rate limiting Step of Fatty Acid Synthesis

Acetyl-CoA Carboxylase

33

Allosteric Regulation of A.C.C.

Citrate; positive
Long chain fatty acids (palmitate); negative

34

Phosphorylation or Dephosphorylation Regulation of A.C.C.

Insulin; Deposph
Epinephrine, Glucagon, AMP; Phosph

35

When is gene expression induced in A.C.C.

high carb/low fat diet

36

What Allosteric Regulators effect Fatty Acid Synthase

Presence of Phosphorylated sugars; increasing activity

37

When is Fatty Acid Synthase Induced or Repressed

Insulin and Glucocoritcoid hormones; increase
High Carb/Low Fat; increase
High Fat Diets; lowers
High PUFA; lowers

38

What does PUFA Stand for

Poly-Unsaturated Fatty Acids

39

What is Leptin Use

Regulate body weight:
Inhibit food intake
Stimulate energy expenditure

40

Where is Palmitate (16 Chain Fatty Acid) Elongated

The Smooth Endoplasmic Reticulum or the Mitochondria

41

Why do we elongate Palmitate (16 Chain Fatty Acid)

The brain used C18-24

42

How many carbons is Palmitate lengthened by

2

43

What does the SER Pathway use as a carbon donor

Malonyl-CoA; giving off CO2

44

What does the Mitochondrial Pathway use as a carbon donor

Acetyl CoA

45

Which two paths do we use to elongate Palmitate (16C)

The SER Pathway or the Mitochondrial Pathway

46

Where do we introduce double to Fatty Acids

Occur in the SER and it uses NADPH and Oxygen

47

What catalyzes the reaction of a saturated fatty acid to an unsaturated fatty acid

Acyl-CoA Desaturases

48

At which point can humans no longer make double bonds on a Fatty Acid

On the alpha side; spot 9

49

Where do we get omega 3 and omega 6 fatty acids?

Diet

50

Can we synthesize omega 3 and omega 6 fatty acids

No; they are past the alpha 9 carbon

51

What negatively regulates desaturases

PUFA's

52

What positively regulates desaturates

Insulin

53

What does Dietary Cholesterol induce

Expression of desaturation point at the 9 Carbon on the alpha side; surpasses all others

54

What are the essential fatty Acids

Linoeic Acid (omega-6)
Linolenic Acid (omega-3)

55

Good source of Omega-3

Fish

56

Good source of Omega-6

Red Meat

57

What is Linoleic Acid used for

To make Arichidonic Acid

58

What does Arichidonic Acid do

Precurosr for eicosanoids

59

What is Linolenic Acid used for

To make Eicosapentanoic Acid and Docosahexanoic Acid