E3 Fatty Acids and Lipolysis

Question 1

which fatty acids cannot be synthesized by the body?

Answer 1

linoleic and alpha linolenic

Question 2

match the nomenclature to the fatty acid.

1. stearic acid
2. oleic acid
3. linoleic acid
4. linolenic acid

A. 18:1w9
B. 18:3w3
C. 18:0
D. 18:2w6

Answer 2

1. C
2. A
3. D
4. B

Question 3

match the nomenclature to the fatty acid.

1. arachidonic acid
2. EPA
3. DHA
4. Palmitic acid

A. 16:0
B. 20:5w3
C. 20:4w6
D. 22:6w3

Answer 3

1. C
2. B
3. D
4. A

Question 4

what are fatty acids stored as?

Answer 4

TGs

Question 5

what are TG’s stored in?

Answer 5

lipid droplets

Question 6

when fatty acids are stored as TGs, what type of bonds are made? what is the backbone?

Answer 6

ester bonds

glycerol backbone

Question 7

T/F. Lipid droplets are extracellular organelles within the cytoplasm.

Answer 7

false; intracellular

Question 8

what are three reasons why TGs are stored in lipid droplets?

Answer 8

1. energy
2. membrane synthesis
3. protect against lipotoxicity

Question 9

define lipolysis.

Answer 9

breakdown of TG to mobilize FAs (3 FFAs and glycerol)

Question 10

T/F. Lipolysis can occur in the GI, vascularly, and intracellularly.

Answer 10

true

Question 11

what are the three lipases in GI lipolysis?

Answer 11

lingual, gastric, and pancreatic

Question 12

where does digestion begin?

Answer 12

mouth and stomach

Question 13

most dietary TAGs breakdown in
A. mouth
B. stomach
C. small intestine

Answer 13

C. small intestine

Question 14

T/F. Lipases cleave ester bonds.

Answer 14

true

Question 15

what protein as considered the “gate keepers” of regulating lipid metabolism?

Answer 15

perilipins

Question 16

what are the contents of lipids that enter the enterocyte?

Answer 16

FFA, MAG, DAG, cholesterol, cholesterol esters

Question 17

______ is formed at the enterocyte and transports dietary lipid and cholesterol.

Answer 17

chylomicrons

Question 18

other than chylomicrons, what are the other lipoprotein complexes?

Answer 18

VLDL, HDL, LDL, IDL

Question 19

as the chylomicron slowly enters the blood, the lipid from the diet goes to what type of tissue?

Answer 19

extrahepatic tissue (adipose and muscle)

Question 20

when is the chylomicron sent to the liver?

Answer 20

as the TG is removed at the target cell and becomes a chylomicron remnant

Question 21

MCFA –> lymph –> blood –> liver via what protein?

Answer 21

albumin

Question 22

LCFA –> lymph –> blood –> adipocyte –> liver via what lipoprotein complex?

Answer 22

chylomicron

Question 23

define vascular lipolysis.

Answer 23

breakdown of TGs from certain lipoprotein complexes

Question 24

what lipase is used during vascular lipolysis?

Answer 24

Lipoprotein Lipase (LPL)

Question 25

is lipoprotein lipase (LPL) extracellular or intracellular?

Answer 25

extracellular

Question 26

what is the location of LPL?

Answer 26

endothelial surface of capillaries

Question 27

T/F. during exercise, there is a decrease concentration of LPL in skeletal muscle.

Answer 27

false; increased LPL

Question 28

when you do not exercise, LPL concentration decreases by how much in skeletal muscle?

Answer 28

10-20 fold

Question 29

what is the reason for LPL production at target cells in muscle? adipose?

Answer 29

``` M= FA oxidation for energy A= re-esterified to be stored as TGs ```

Question 30

define intracellular lypolysis.

Answer 30

breakdown of TGs located in intracellular lipid droplets

Question 31

what are the three intracellular enzymes associated with intracellular lipolysis?

Answer 31

adipose triglyceride lipase (ATGL) hormone sensitive lipase (HSL) monoacylglycerol lipase (MGL)

Question 32

match the rxn to the enzyme. A. ATGL B. HSL C. MGL 1. MAG --> FFA +glycerol 2. TAG --> DAG 3. DAG --> MAG

Answer 32

A. 2 B. 3 C. 1

Question 33

which intracellular enzyme is the key regulatory enzyme in intracellular lipolysis? why?

Answer 33

HSL; lipolysis is regulated by hormones= glucagon and epinephrine

Question 34

intracellular lipolysis is regulated by hormones and triggers the cAMP cascade. what type of regulation is this?

Answer 34

covalent modification

Question 35

what will stimulate ATGL?

Answer 35

glucocorticoids epinephrine fasting

Question 36

what will inhibit ATGL?

Answer 36

insulin | food intake

Question 37

what will strongly stimulate HSL?

Answer 37

B-adrenergics (epinephrine, norepinephrine, phosphorylation) | glucagon

Question 38

what will strongly inhibit HSL?

Answer 38

insulin

Question 39

T/F. There is more information on what stimulates and inhibits MGL than ATGL and HSL.

Answer 39

false; not much is known

Question 40

when epinephrine/glucagon bind to the PM and initiate the cAMP cascade, what will PKA phosphorylate and activate?

Answer 40

perilipin and HSL

Question 41

when perilipin is phosphorylated and activated by PKA, what enzyme will become activated?

Answer 41

ATGL

Question 42

when HSL is phosphorylated and activated by PKA, what enzyme will become activated?

Answer 42

MGL

Question 43

what hormone will inhibit phosphorylation of perilipin and HSL, therefore inhibiting lipolysis?

Answer 43

insulin

Question 44

when FFA from ATGL, HSL, MGL is released into the blood and transported to target tissues, what protein is it bound to? how many FFA can it carry?

Answer 44

albumin; apx 10 FFAs

Question 45

what enzyme will convert glycerol to G-3-P?

Answer 45

glycerokinase

Question 46

T/F. There is a lot of glycerokinase in adipose.

Answer 46

false; absent in adipose

Question 47

once glycerol is converted to G-3-P via glycerokinase, what will G-3-P become? what two pathways can it enter?

Answer 47

DHAP; glycolysis and GNG

Question 48

lipolysis of stored TGs in an adipocyte results in 3 FFAs and glycerol. where will the glycerol go? FFAs?

Answer 48

glycerol --> hepatocyte | 3FFAs --> target cells (e.g. muscle)

Question 49

matching. ``` A. convert to DHAP B. B-oxidation C. make ATP D. enter glycolysis and GNG E. hepatocyte F. produce acetyl CoA G. enter CAC H. target cells ``` 1. glycerol 2. 3 FFAs

Answer 49

``` A. 1 B. 2 C. 2 D. 1 E. 1 F. 2 G. 2 H. 2 ```