Lipid Metabolism

Front 1

Major classes of lipoproteins?

Back 1

chylomicrons, very low density lipoprotein, intermediate density lipoprotein, low density, high density

Front 2

what are chylomicrons produced from and where?

Back 2

intestinal cells, from dietary lipids

Front 3

where is VLDL produced, of what?

Back 3

liver, dietary carbohydrate

Front 4

where are VLDL and chylomicrons hydrolyzed? by what? to what?

Back 4

blood.
lipoprotein lipase to fatty acids and glycerol

Front 5

what are fatty acids converted to in adipose tissue?

Back 5

converted to triaceylglycerol and stored

Front 6

IDL consists of what?

Back 6

remaining VLDL after digestion of some of the TGs

Front 7

Fate of IDL? where?

Back 7

endocytosed by liver cells and digested by lysosomal enzymes or converted to LDL by further digestion of TGs.
Occurs in liver and peripheral tissues

Front 8

How does cholesterol travel?

Back 8

as a component of blood lipoprotein. synthesized by many tissues.

Front 9

Key cholesterol regulatory enzyme?

Back 9

HMG CoA reductase

Front 10

Fate of cholesterol in liver? endocrine glands?

Back 10

bile salts, steroids

Front 11

Purpose of HDL?

Back 11

transfer proteins to chylomicrons and VLDL. Picks up cholesterol from tissue and returns it to liver. (good cholesterol)

Front 12

Fate of fatty acids in fasting? in the liver?

Back 12

oxidized to energy.
Ketone bodies in the liver
which are then oxidized by tissues and kidney.

Front 13

Eicsanoids are derived from what?

Back 13

polyunsaturated fatty acids.

Front 14

How are polyunsaturated fatty acids classified?

Back 14

according to position of first double bond from omega end (3 or 6)

Front 15

phosphoglycerides contain what?

Back 15

fatty acid esterified to position 1 and 2 and a phosphoryl at group 3

Front 16

Phoshoglycerides are the major component of what?

Back 16

lipid bilayer (hence phospholipid bilayer)
cholesterol is in there too!

Front 17

Digestion of lipid requires what 2 enzymes?

Back 17

bile salts and pancreatic secretions (lipase)

Front 18

lipase breaks TGs into what?

Back 18

2-monoacylglycerols and free fatty acids, packages them into micelles

Front 19

bile salts do what?

Back 19

emulsify, break down into tiny droplets

Front 20

Fatty acids in micelles are activated by what enzyme? FORM WHAT?

Back 20

thiokinase (fatty acyl CoA synthase)
Form fatty acyl CoA

Front 21

fatty acyl CoA reacts with______ to form a ________

Back 21

diacylglycerol

triacylglycerol

Front 22

Once absorbed in the gut,TGs travel to ________ system packaged as _________and eventually enter the _______________(circulation)

Back 22

lymphatics
chylomicrons
blood

Front 23

de novo synthesis of fatty acids from acetyl CoA occurs where?

Back 23

cytosol

Front 24

Acetyl CoA is derived mostly from what?

Back 24

glucose

Front 25

Acetyl CoA is converted by acetyl CoA carboxylase to __________
reversible?

Back 25

acetyl CoA carboxylase
malonyl CoA
irreversible

malonyl-CoA is produced and inhibit the transfer of the fatty acyl group from acyl CoA to carnitine with carnitine acyltransferase, which inhibits the beta-oxidation of the fatty acid in mitochondria.

Front 26

how many carbons are added at a time to the growing fatty acyl chain? where do the carbons come from?

Back 26

2
3 carbon malonyl CoA

Front 27

What energy source is needed form fatty acid synthesis?

Back 27

NADPH

Front 28

where is NADPH produced?

Back 28

pentose phosphate pathway

Front 29

palmitate is produced from what reaction? converted to what?

Back 29

fatty acid synthesis complex
fatty acyl CoAs by elongation and desaturation

Front 30

fatty acyl CoA combines with WHAT, WHERE to form triacylglycerols?

Back 30

glycerol-3 Phosphate
liver

Front 31

How are TGs packaged? where are they secreted?

Back 31

VLDL
blood

Front 32

glucose enters the liver cell and is converted to what via glycolysis?

Back 32

pyruvate, which enters the mitochondria

Front 33

pyruvate is converted to ________ by pyruvate dehydrogenase?

Back 33

acetyl CoA

Front 34

pyrvuate is converted to _________ by pyrvuate carboxylase?

Back 34

oxaloacetate

Front 35

Because Acetyl CoA cannot cross the mitochondrial membrane to enter the cytosol for fatty acid synthesis

Back 35

acetyl CoA and oxaloacetate condense to form Citrate, which can cross the membrane

Front 36

citrate is cleaved to what in the cytosol? by what enzyme? What does the enzyme require?

Back 36

oxaloacetate and acetyl CoA
CITRATE LYASE
ATP and insulin

Front 37

oxaloacetate is reduced in the cytosol to what?
what energy source used?

Back 37

malate
NADH

Front 38

in the cytosol, malate is converted to_______ and NADPH is produced, CO2 released
What is the enzyme that catalyzes this reaction?

Back 38

pyruvate
malic enzyme

Front 39

pyruvate Can reenter the mitochondria and is reutilized

Back 39

NADPH supplies reducing equivs for reactions in fatty acid synthase complex

Front 40

After citrate leaves the mitochondria, it is converted to _______, which goes on to be used for fatty acid synthesis

Back 40

acetyl CoA

Front 41

Fatty Acid Synthesis complex is located where?

Back 41

in the cytosol

Front 42

NADPH is produced by which two pathways?

Back 42

malic enzyme
pentose phosphate pathway

Front 43

acetyl CoA reacts with what residue and transfers what?

Back 43

phosphopantetheinyl residue
acetyl group

Front 44

malonyl CoA forms a thioester with what group?

Back 44

phosphopantetheinyl sulfhydryl group

Front 45

Malonyl CoA forms from what?
What kind of reaction?
Requires what coenzymes?

Back 45

acetyl CoA
carboxylation
ATP and biotin

Front 46

what enzyme catalyzes the formation of malonyl CoA from acetyl COA?

Back 46

acetyl CoA carboxylase
activated by dephosphorylation, citrate, and insulin

Front 47

Elongation of the growing strand until how many carbons are formed? name this molecule

Back 47

16
palmitate

Front 48

fate of palmitate?

Back 48

can be desaturated to a series of fatty acids

Front 49

In intestinal cells TGs are packaged as what?

Back 49

chylomicrons

Front 50

Liver uses glycerol to make what?

Back 50

glycerol 3-P by a reaction that requires ATP and is catalyzed by glycerol kinase

Front 51

adipose tissue cannot generate glycerol-3P from glycerol because it lacks_______

Back 51

glycerol kinase

Front 52

liver and adipose can convert glucose through glycolysis to DHAP which reduces to _______

Back 52

glycerol 3-P

Front 53

What state does TG production occur in?

Back 53

Fed state

Front 54

what enzymes are active in the fed state?

Back 54

glucokinase, phosphofructokinase 1, pyruvate kinase
pyruvate deydrogenase is dephosphorylated and active
pyruvate carboxylase is activated by acetyl CoA
citrate lysase is induced
acetyl CoA carboxylase is induced, activated by citrate
fatty acid synthesis complex is induced

Front 55

Malonyl CoA is the product of what?

Back 55

acetyl CoA carboxylase

Front 56

malonyl CoA inhibits carnitine acyltransferase I and prevents _______from entering the mitochondira to undergo B-oxidation

Back 56

synthesized fatty acids

Front 57

Synthesis of TGS in adipose tissue must make its own glycerol because it lacks?

Back 57

glycerol kinase

Front 58

glucose is converted to DHAP to later form __________which is used to produce glycerol

Back 58

glycerol-3P

Front 59

The two major carriers of TGs in the blood are...

Back 59

VLDL
chylomicrons

Front 60

broken down TGs have two fates:

Back 60

1. oxidized for energy
2. converted to TGs and stored

Front 61

glycerol is converted to ________ and oxidized for energy in the liver

Back 61

DHAP: dihydroacetone phosphate (a member of the glycoytic pathway)
Glycerol (Glycerol kinase) Glycerol-3-phosphate (Glycerol-3-phosphate dehydrogenase) Dihydroxyacetone phosphate (DHAP)
(Triosephosphate isomerase) Glyceraldehyde 3-phosphate

Front 62

lipoproteins are made up of:

Back 62

triacylglycerols
cholesterol
cholesterol esters
phospholipids
proteins

Front 63

chylomicrons are the most/least dense?

Back 63

least, they have the most TGs

Front 64

IDL is derived from what?

Back 64

VLDL

Front 65

LDL has what ratio of protein/TGs

Back 65

highest content of cholesterol
less TGs and more protein

Front 66

what activated lipoprotein lipase? what increases it?

Back 66

apo c11
insulin

Front 67

how are chylomicrons taken up?

Back 67

by endocytosis of liver cells, contents are degraded by lysosomal enzymes and products are released into the cytosol

Front 68

Where is VLDL synthesized?

Back 68

liver, after high-carb meals

Front 69

VLDL is digested where? by what? into what?

Back 69

peripheral tissues (adipose, muscle) by lipoprotein lipase, into IDL

Front 70

IDL returns to the liver and is degraded by what?

Back 70

lysosomal enzymes

Front 71

HDL is synthesized by the ______and released into the blood

Back 71

liver

Front 72

In the fasting state, what is the fate of TGs?

Back 72

lipolysis

Front 73

glucagon levels stimulate lipolysis through what pathway?

Back 73

cAMP rises, protein kinase A is activated
protein kinase A phosphorylates and activates Hormone sensitive lipase HSL

Front 74

fatty acid is carried by what in the blood?

Back 74

albumin

Front 75

fatty acids are converted to _____in the liver

Back 75

ketone bodies

Front 76

long chain fatty acids are activated by:
forming what?

Back 76

ATP
coenzyme A
forming fatty acyl CoA

Front 77

What does fatty acyl CoA react with in the outer mitochondrial membrane?

Back 77

carnitine, forming fatty acyl carnitine
enzyme: fatty acyl transferase I (CATI)aka CPTI

Front 78

fatty acyl Carnitine passes to the inner membrane where it reforms to ___________

Back 78

fatty acyl CoA, which then enters the matrix

Front 79

CATI is inhibited by? why?

Back 79

malonyl CoA
it is an intermediate in fatty acid SYNTHESIS! prevents a futile cycle

Front 80

fatty acyl CoA undergoes______once inside the mitochondrion

Back 80

beta-oxid

Front 81

Beta Oxidation:
what is the first step?

Back 81

1. FAD accept hydrogens from fatty acyl CoA, enol CoA is formed. enzyme: acetyl CoA dehydrogenase

Front 82

Step 2,3,4 beta ox?

Back 82

H20 added across double bond....just go look it up

Front 83

16 carbon palmitoyl CoA undergoes how many repetitions?

Back 83

seven, in the last one two acetyl CoA are formed

Front 84

energy formed from one palmitoyl CoA?

Back 84

7 FADH2=2ATP each
7 NADH=3ATP each
8 acetyl CoA=12 ATp each
total: 131-2ATP=129

Front 85

Odd chain fatty acids produce...

Back 85

acetyl CoA and propionyl CoA

Front 86

propionyl CoA can be converted to...

Back 86

glucose!