Lipids in Energy Metabolism - FA & TG

Question 1

Lipid in blood transport

Answer 1

PL & TG: lipoproteins

FA: Bound to plasma proteins

Question 2

Lipoprotein definition

Answer 2

Spherical lipid droplet containing at least one apoprotein

Question 3

How are FA stored?

Answer 3

Oil droplets of neutral TG to prevent potential destruction to cell membranes, have high energy density

Question 4

TG lipoprotein transport issues

Answer 4

Lipases release FA from stored TG
FA transported across membranes
TG resynthesized into TG

Question 5

TG cycle - Dietary TG (direct step)

Answer 5

Dietary TG –> GI lipase –> FA

Question 6

TG cycle - liver redistribution to tissues (3 items)

Answer 6

• Endocytoses CMR & releases TG
• Synth TG from FA (from meal glucose)
• Assembly & export of VLDL

Question 7

Liver & TG

Answer 7

Assembles it into VLDL to be secreted

Only small amount of TG for local use

Question 8

Adipose & TG

Answer 8

Stores TG in oil droplets for body and releases FA into plasma during fasting for fuel

Question 9

FA synth from glucose (pathway)

Answer 9

Glucose –> pyruvate –> citrate –> Acetyl CoA – Malonyl CoA –> palmitate –> sat & unsat FA

Question 10

FA synth from Acetyl CoA (pathway)

Answer 10

Acetyl CoA –> Malonyl CoA –> palmitate –> sat &a unsat FA

Question 11

ATP Citrate Lyase (ACLY) fx

Answer 11

Citrate –> Acetyl CoA

Question 12

Acetyl CoA Carboxylase (ACC) fx

Answer 12

Acetyl CoA –> Malonyl CoA

Question 13

FA synthase fx

Answer 13

Malonyl CoA –> palmitate

Note that NADPH –> NADP at this step

Question 14

FA synth is upregulated by

Answer 14

insulin

substrate levels

Question 15

ACC regulation - stimulated by:

Answer 15

Insulin (+)

Citrate (+)

Question 16

Fructose metabolism

Answer 16

Enters glycolysis after PFK-1 -

Metabolites activate ACC to induce FA synth

Question 17

TG synth

Answer 17

Glucose –> FA –> acyl CoA

Glycolytic intermed DHAP –> glycerol –> glycerol-3-P

Question 18

Acyltransferases

Answer 18

Attach an acyl CoA to glycerol-3-P –> TG

Question 19

VLDL lipoprotein assembly is driven by ______, then immediately _____

Answer 19

Driven by TG, then immediately secreted

Question 20

HSL definition and action

Answer 20

Hormone sensitive lipase

adipocyte specific lipase releases FAs + glycerol from TG

Question 21

Fate of FA released from TG

Answer 21

Cellular fuel for muscle and other cells.

Question 22

Fate of Glycerol from TG

Answer 22

Taken up by liver as substrate for gluconeogenesis

Question 23

HSL regulation - stimulated by:

Answer 23

Glucagon (+)
Cortisol (+)
EPI (+)
Growth Hormone (GH) (+)

Question 24

FA B-Oxidation products (2+1 items)

Answer 24

Acyl CoA –> NADH & FADH2

Acyl CoA –> Acetyl CoA

Question 25

Where is plasma FA converted in acyl CoA for B-Ox?

Answer 25

Cytosol

Question 26

Carnitine palmitoyl transferase 1 (CPT-1)

Answer 26

Transport Acyl CoA along with the carnitine shuttle into mitochondria for B-Ox

Question 27

B-Ox enzymes function

Answer 27

Generate acetyl CoA & lots of NADH and FADH2 for ETC

Question 28

Hepatocytic cytosolic FA are all converted into ____

Answer 28

Acyl CoA

Question 29

Cytosolic Acyl CoA is transformed into

Answer 29

--> TG

Question 30

Mitochondrial Acyl CoA is transported in by ____ and undergoes _____ to yield ____

Answer 30

Transported in by CPT-1 | -->B-Ox --> ATP

Question 31

Malonyl CoA inhibits _____ and is formed from ____ by _____

Answer 31

Inhib CPT-1 | formed from citrate by ACCC

Question 32

CPT-1 activity is always _____ unless ______ (inhib, stim) by _____

Answer 32

Always high unless inhibited by malonyl CoA

Question 33

Acute lipid dysreg leads to

Answer 33

Ketoacidosis

Question 34

Chronic lipid dysreg leads to

Answer 34

Atherosclerosis

Question 35

Steatosis

Answer 35

Early form of fatty liver dz (FLD) | Hepatocytes accumulate excess TG

Question 36

Acute effects unique to hyperglycemia

Answer 36

Hyperosmolar hyperglycemic state (HSS)

Question 37

Chronic effects unique to hyperglycemia

Answer 37

Microvascular: Retinopathy Nephropathy Neuropathy

Question 38

Low insulin effect:

Answer 38

High glucagon:insulin ratio --> inc hep VLDL synth w dec conversion to remnants --> Excess VLDL --> Atherosclerosis --> CVD

Question 39

Excess cytosolic acyl CoA increases

Answer 39

- Inc adipose lipolysis --> Inc hep FA uptake | - Inc hep de novo FA synth

Question 40

Excess hepatic TG causes

Answer 40

- Excess cytosolic acyl CoA | - Dec assembly/export of VLDL

Question 41

ACC regulation - inhibited by:

Answer 41

``` Glucagon (-) Acyl CoA (-) ```

Question 42

HSL regulation - Inhibited by:

Answer 42

Insulin (-)

Question 43

B-Ox enzymes - location

Answer 43

In mitochondria

Question 44

When is [Malonyl CoA] low?

Answer 44

[Low] during fasting bc glucagon inhib ACC

Question 45

When is [Malonyl CoA] high?

Answer 45

[High] when fed bc insulin inc ACC

Question 46

What factors also tie into atherosclerosis?

Answer 46

Hyperglycemia, HTN obesity

Question 47

Excess cytosolic acyl CoA decreases

Answer 47

-Dec hep FA ox

Question 48

What role do capillaries play in the TG dietary cycle and tissue redistribution?

Answer 48

Lipoprotein lipase (LPL) in capillaries releases FA from TG, leaving CMR

Question 49

What role does adipose play in TG dietary cycle and tissue redistribution?

Answer 49

Adipose FA uptake and TG synth

Question 50

Fructose metabolism location

Answer 50

Only in liver

Question 51

How are Acyltransferases regulated?

Answer 51

subtrate levels

Question 52

Prognosis of steatosis

Answer 52

Benign, but can progress to steatohepatitis, w hep inflam and hep apoptosis

Question 53

What role do enterocytes play in the TG dietary cycle?

Answer 53

TG synth and CM assembly

Question 54

Fructose is uptaken by ____ during metabolism

Answer 54

GLUT5

Question 55

Fructose metab reg/inhib

Answer 55

no allosteric inhib Evades (-) feedback reg

Question 56

FA released from TG is bound to _____

Answer 56

albumin

Question 57

Pathway of fate of glycerol from TG

Answer 57

Glycerol --> kinase --> glycerol-3-P --> Dehydrogenase --> DHAP

Question 58

CPT-1 fx

Answer 58

transports Acyl CoA into mitochondria for B-Ox

Question 59

Steatosis is common with ______

Answer 59

Obesity TDM EtOH abuse

Question 60

What does high [Malonyl CoA] cause?

Answer 60

[High] causes Acyl CoA to stay in cytosol