Lecture 5 Flashcards

1
Q

When lipids enter enterocytes they travel to E.R. where they are what?

A

Biosynthesized

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2
Q

LCFA that enter ER have how many carbons?

A

14>

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3
Q

What happens to LCFA that enter E.R.

A

Made into AcylCoA by AcylCoA Synthase (thiokinase)

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4
Q

Because LCFA that enter E.R. are acylated what is low?

A

FFA

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5
Q

Acyl-FA is also recognized as what?

A

CoA-Thioester which is a substrate for Beta oxidation

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6
Q

Wwhat is a substrate for Beta oxidation?

A

CoA Thioester

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7
Q

Can FFA diffuse into mitochondria?

A

Yes but they can not be oxidized

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8
Q

If a FFA diffuses into mitochondria, can they be oxidized?

A

No

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9
Q

What is used by TAG Synthase to convert 2-monoglycerols to TAG?

A

Acyl-CoA aka CoA thioester

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10
Q

2 parts of TAG synthase?

A

MAG acyltransferase

DAG acyltransferase

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11
Q

Lysolecithin (lysophospholipids) convert to phospholipids by what enzyme?

A

acyltransferase

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12
Q

Cholesterol is acted on by acyl cholesterol transferase (ACAT) to make what?

A

Cholesteryl ester

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13
Q

Do erythrocytes have mitochondria?

A

No

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14
Q

Can brain oxidize FFA?

A

No, because it has a blood brain barrier

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15
Q

3 hormones that facilitate lipolysis

A

Glucocorticoids
Growth Hormone
Thyroid hormone

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16
Q

Glucocorticoids
Growth hormone
Thyroid hormone

synthesize what?

A

Hormone sensitive lipase

Which is the rate controlling step in lipolysis

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17
Q

What breaks down TAG in adipose?

A

ATGL

adipose triglyceride lipase

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18
Q

What breaks down monoacylglycerol?

A

MAG

Monoacylglycerol lipase

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19
Q

In cushings disease there is what?

A

Excess glucocorticoid

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20
Q

In cushings disease there is excess glucocorticoid which leads to what?

A

long-term steroid therapies where fat is reduced in lower extreme but greatly increased in truncal obesity leading to buffalo hump showing that ab and neck adipocytes are not very reactive to these hormones

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21
Q

Insulin ensures that TAG are synthesized in what state and degraded in what state?

A

Synthesized

Degraded

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22
Q

Which nervous system ensure release of TAG during stress?

A

Sympathetic

23
Q

Albumin bound FA have a high turnover time in plasma of how long?

A

3 minutes

24
Q

What happens to glycerol in liver?

A

Go into glucose synthesis

25
Q

Intestine and liver release _____ which adipocytes can’t.

A

lipoproteins

adipocytes can only release FFA (unesterified)

26
Q

What 3 components of the body can not oxidize FA

A

Brain
Erythrocytes
Neurons

27
Q

Beta oxidation metabolizes what type of Fats?

A

Saturated

28
Q

To be oxidized Short FA must have what?

A

Even number carbon chain

Chain length of 18-20

if not they need additional enzymatic reaction

29
Q

WHere does beta oxidation occur?

A

Mitochondrial matrix

30
Q

DUring beta oxidation what happens to Acyl-CoA FA

A

2 carbon atoms must be removed to make acetyl-CoA, NADH, and FADH2

31
Q

What must occur for a FA with less than 14 carbons to diffuse into mitochondria

A

must be protonated

32
Q

What carries LCFA from cytosol into mitochondrial matrix?

A

Carnitine through a carnitine shuttle

33
Q

First step of transferring a LCFA into mitochondrial matrix

A

Acyl FA group is transferred to the OH group of carnitine forming acyl carnitine

34
Q

What transfer the AcylFA group to the OH group of carnitine?

A

Carnitine-Palmitoyl transferase
or
CAT

35
Q

Carnitine Palmitoyl transferase has 2 forms. Explain them

A

CPT1 is the outer membrane

CPT2 is the inner membrane

36
Q

What crosses mitochondria membrane via carnitine shuttle?

A

Acyl-Carnitine and Carnitine via diffusion using Carnitine acylcarnitine translocase

37
Q

What enzyme helps transfer Acyl Carnitine and Carnitine across mitochondrial membrane

A

Carnitine-Acylcarnitine

Translocase

38
Q

Once the Carnitine-AcylCarnitine gets across mitochondrial membrane what happens?

A

Carnitine Palmitoyl Transferase 2 catalyzes the carnitine group and adds Coenzyme A back

39
Q

Does SCFA or MCFA need carnitine?

A

No they can diffuse passively where they are acylated

40
Q

What inhibits CPT1 from transferring LCFA into mitochondria?

A

Malonyl CoA

41
Q

WHen Malony CoA inhibits CPT1, LCFA can’t get into mitochondria because what?

A

FA synthesis is occuring in cytosol and the new palmitate can not enter either

42
Q

Where does carnitine come from?

A

Diet or liver and kidney make them out of lysine and methionine

43
Q

Can heart and skseletal muscle make carnitine?

A

No

44
Q

Where is carnitine stored?

A

Skeletal muscle

45
Q

Carnitine removes what?

A

Branch chain acyl group that are made when BCAA are catabolized for energy

46
Q

What happens to acyl groups the body can not catabolize?

A

trapped and excreted at renal level by carnitine

47
Q

Deficiency of carnitine can lead to what?

A

InAbility of tissue to use LCFA as a source of energy

Build up of Branch Chain Acyl Groups and FFA in tissuess

48
Q

What causes carnitine deficiency?

A

Liver failure
Malnutrition
Strict Diet
Increase need due to infection, burns, pregnancy, hemodialysis.

Congenital deficiency; where tubular reabsorption of carnitine is bad, or cellular uptake of carnitine is bad

49
Q

What does hemodialysis lead to?

A

Extracting carnitine from the blood

50
Q

CPT1 deficiency can lead to what?

A

Impair liver tissue ability to make glucose in fasting state

51
Q

CPT1 deficiency impair liver tissue ability to make glucose in fasting state leading to what?

A

Hypoglycermia or Death

52
Q

CPT 2 deficiency occurs mainly where?

A

Cardiac and skeletal muscles

53
Q

When CPT2 is deficient what occurs?

A

Cardiomyopathy
muscle weakness
myoglobinemia

54
Q

How do you treat carnitine deficiency?

A
High Carb diet,
Low LCFA diet
Supplement MCFA
avoid fasting
Supplement carnitine