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Tim's Cards > Metabolism 2 - Part 1 > Flashcards

Metabolism 2 - Part 1 Flashcards

1
Q

What is the term for esterified fatty acids?

A

Triacylglycerol

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2
Q

Name 7 classes of lipids

A 
Sphingolipids
Glycolipids
Glyceropholspholipids
Steroids
Triacylglycerol
Fatty Acids 
Vitamins (ADEK)
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3
Q

Name a 2nd messenger lipid

A

DAG

diacylglycerol

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4
Q

Chains on the hydrocarbon part of fatty acids vary from ____ to ____ in length.

A

4-36

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5
Q

T/F

A fatty acid is nonpolar

A

False

carboxyl end is an acid

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6
Q

A molecule (like a fatty acid) that has both hydrophilic and hydrophobic characteristics is…

A

Amphipathic

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7
Q

What is the most common Fatty Acid in the body?
How many carbons?
saturation?

A

Palmitate
16
saturated

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8
Q

Describe the 2 notations counting carbon saturation in fatty acids

A

From COOH = delta (superscript)

From omega = n-6, etc

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9
Q

Where are the alpha, beta, and omega carbons in a FA chain?

A

alpha - one away from C1 (the carboxylic Carbon)
beta - two away from C1
omega - the last C

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10
Q

Palmitate is ______

Pamitoleic is ______

A

Saturated

Unsaturated

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11
Q

Mammalian enzymes cannot make a double bond more than ____ carbons away from the carboxylic end.

A

9

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12
Q

What is the name of an essential fatty acid required in diet

comes in omega 3 and 6 forms

A

Linoleic acid

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13
Q

Why do omega 3 and omega 6 pathways compete with each other?

A

They share the same enzymes

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14
Q

What do essential fatty acids like linoleic acid serve as a precursor for?

A

Eicosonoids

prostaglandins

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15
Q

What effects do eicosonoids have on the cell?

What is an example (precursor linoleic acid)

A

hormone-like

Arachidonic acid

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16
Q

What is the difference between a simple and a mixed triacylglycerol?

A

simple - has same carbon chains

mixed - has different (saturation levels/length) chains

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17
Q

What molecule is at the crossroads between making triacylglycerols and phospholipids?

A

Phosphatidate

phosphatidic acid

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18
Q

Why are triacylglycerols such a good form of energy storage?

A

Reduced and Anhydrous

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19
Q

16:0

A

Palmitic Acid

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20
Q

Name 5 things fatty acids are precursors to?

A 
Glycolipids
Phospholipids
Sphingolipids
Prostaglandins
Cholesteryl esters
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21
Q

Short, medium, and long Fatty Acid lengths:

A

Short - 2-5 C’s

Medium - 6-12 C’s

Long- 12+

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22
Q

Short and unsaturated Fatty Acids tend to be:

Long and saturated Fatty Acids tend to be:

A

oils

solids

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23
Q

PUFA and MUFA tend to be oils. What do they stand for?

A

Polyunsaturated fatty acids

monounsaturated fatty acids

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24
Q

Where are trans fats made?

Why bad?

A

industrial hydrogenation processes
body lacks enzymes to break down
(only breaks cis)

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25
Q

What is the major intermediate found both in triacylglycerides and phospholipids?

A

Phosphatidic acid

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26
Q

What are 2 essential fatty acids?

A

Linoleic and alpha linoleic acid

remember - precursor to eicosonoids

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27
Q

Arachidonic acid is synthesized entirely by what fatty acid?

A

Linoleic Omega 6 form

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28
Q

What two things distinguish apple (as opposed to pear) shape?

A

Metabolically active and dangerous

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29
Q

Where does lipid digestion begin?

A

in mouth (Lingual Lipase)

but this process isn’t efficient in adults

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30
Q

What type of lipid digestion occurs in the stomach (what enzymes are involved)?

A

Acid-stable Lingual lipase (slow)

Gastric lipase (pH 7 optimal - only useful for SCFA and medium chain fatty acids)

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31
Q

What converts macroscopic fat cells into micelles?

A

Bile salts

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32
Q

What are bile acids made from and what are they secreted as?

A

cholesterol derivatives

secreted as taurine and glycine salts

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33
Q

Name the 3 bile acids

A

Cholic
Glycocholic
Taurocholic

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34
Q

What is the process of bile acid reabsorption to the liver via the portal vein called?

A

Enterohepatic Cycle

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35
Q

What two steps happen to create fatty acids in the intestine?

A

Bile salts break down into micelles

Pancreatic lipase break into FA’s
goes into the unstirred layer

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36
Q

What is the small peptide hormone released by the jejunum in response to chyme?

A

Cholecystokinin

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37
Q

What are 3 functions of Cholecystokinin?

A

Stimulates gall bladder release
Releases pancreatic enzymes
Slows digestion from stomach (gastric emptying)

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38
Q

What is released into the duodenum in response to low pH of chyme?
What does it induce?

A

Secretin

induces pancreas to release bicarbonate (buffer)

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39
Q

What is the most important (for this class) pancreatic enzyme?
What does it do?
What are two others?

A

Pancreatic Lipase (leaves middle leg from TAGs)

Cholesterol esterase
Phospholipase A2

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40
Q

What stabilizes the lipid-water interface interactions (surface area of which digestion depends) of Pancreatic Lipase?

A

Colipase

also secreted by pancreas

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41
Q

Procolipase is cut by trypsin to form Colipase, the other end is a 5 AA sequence called Enterostatin that acts as a satiety signal. What is that sequence?

A

Ala-Pro-Gly-Pro-Arg

damn near palindromic

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42
Q

What substrate and enzyme create cholesterol in the intestine?

A

Cholesteryl ester + Cholesteryl esterase (hydrolyzes)

= Cholesterol + Fatty acid

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43
Q

The proenzyme of Phospholipase A2 is activated by…

A

Trypsin

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44
Q 
Phospholipase A2 (after trypsin activation) pathway first removes FA at C2, then C1
What are the substrates of this rxn?
A

phospholipid (remove C1) > lysophospholipid (remove C2) > glycerophosphoryl base

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45
Q

What Beta-Clam structure protects the cell from the soapy nature of fatty acids and quarantines it inside the cell before repackaging and exit to the lymphatic?

A

FABP2/I-FABP

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46
Q

What 2 steps occur in an intestinal cell after FA absorption that need to occur before fat leaves?

A

FA > Fatty acyl CoA > Chylomicron (with polar outer layer)

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47
Q

What types of fatty acids do not need to be repackaged in the intestinal mucosal cell?
What carries them around the body?

A

Short and Medium chain fatty acids

Serum Albumin

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48
Q

What happens to Fatty Acids and cholesterol before they are repackaged into chylomicrons?

A

FA’s re-esterified into TAG’s

Cholesterol re-esterified into cholesteryl ester

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49
Q

CE
PL
substrate>enzyme>products

A

Cholesteryl ester > cholesteryl esterase > cholesterol

Phophatidylcholine > Lipase > glycerylphosphorylcholine

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50
Q

TAG

substrate>enzyme>product

A

Triacylglycerol > pancreatic lipase > 2-monoacylglycerol

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51
Q

What is lingual lipase’s target?

A

Phophatidylcholine (PL)

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52
Q

Why is Gastric lipase useful if its optimal pH is around 7?

A

It’s only really used in babies.

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53
Q

What does pancreatic lipase break a TAG into?

A

2 Fatty Acids

1 Monoglyceride

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54
Q

What peptide hormone is responsible for stimulating the digestion of fat and protein?

(also acts as a hunger suppressant)

A

CCK

cholecystokinin

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55
Q

What does FACS stand for?

trapping mechanism

A

Fatty Acyl CoA Synthetase

remember: works on both FA>TAG and sterol>steryl

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56
Q

What is found in a chylomicron?

What is found on a chylomicron?

A

Triglycerides (mostly)

Apo B48, phospholipid, free cholesterol, ApoA

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57
Q

What hydrolyzes chylomicrons?

A

Lipoprotein Lipase (LPL)

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58
Q

Where are FFA’s, monoacylglycerides, and cholesterol found?

Where are TAG’s, cholesteryl ester, glycerylphophorylcholine found?

A

Intestinal lumen

mucosal intestinal cells

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59
Q

Trace chylomicron to blood

A

Intestinal mucosal cells > lymph > Subclavian vein via thoracic duct > superior vena cava

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60
Q

List the lipoproteins from biggest to smallest

A 
Chylomicron
VLDL
LDL
IDL
HDL
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61
Q

What is the major difference between a chylomicron and VLDL?

A

Chylomicron carries dietary fat

VLDL carries synthesized fat

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62
Q

What does the shell of a chylomicron contain?

A

Apolipoproteins

Apo B48 and Apo A

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63
Q

What is a known marker for Alzheimers?

A

allele marker for ApoE

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64
Q

What docks to lipoprotein lipase in the capillary?

A

Apo CII

65
Q

Where do Chylomicrons pick up ApoCII and ApoE?

A

HDL

66
Q

After ApoCII activates lipoprotein lipase, where do TAG’s generally go?
Where does glycerol go?

A

Heart, muscle, adipose tissue

Liver

67
Q

How is the chylomicron remnant taken up by the liver?

A

ApoE receptors

68
Q

Fatty Acid + CoA + ATP >

this is the rxn allowing cell to hold on to FA

A

Acyl CoA + AMP + PPi

69
Q

In the liver, what are excess fats (and indirectly carbs) packaged into?

A

VLDL

70
Q

Name 5 apolipoproteins in VLDL.

A 
ApoB-100
ApoC-I
ApoC-II
ApoC-III
ApoE
71
Q

What lipoprotein do nascent VLDL have on their surface?

A

ApoB-100

72
Q

Where does VLDL pick ApoC-II and ApoE?

remember: ApoC-II interacts with lipoprotein lipase to release FA’s from TAGs into cells)

A

HDL

73
Q

How is LDL formed?
What happens to its surface proteins?
What is left over in LDL?

A

VLDL releases TAGs until its IDL then LDL

Apo C-II and ApoE are returned to HDL

Cholesterol

74
Q

What is the primary function of LDL?

A

Delivery of Cholesterol

75
Q

How does LDL bind cells to deliver cholesterol?

What appears to block this process (thus raising blood cholesterol levels)?

A

ApoB-100 receptor mediated endocytosis

Saturated fatty acids

76
Q

What 2 apolipoproteins does HDL provide (act as a reservoir) for chylomicrons and VLDL?

A

ApoC-II and ApoE

77
Q

How does HDL scavenge cholesterol from membrane lipid lecithin?

A

A-1 activates LCAT (Lecithin Cholesterol Acyl Transferace - aka PCAT)

converts membrane lipids FA’s to cholesterol

78
Q

What exchanges choleteryl ester from HDL for TAG from VLDL?

A

Cholesteryl ester transferase protein (CETP)

79
Q

Apolipoproteins on a:
Nascent chylomicron
“mature”
“spent”

A

ApoB48

ApoB48, ApoCII, ApoE (latter 2 from HDL)

ApoB48, ApoE (latter gets into liver, ApoCII taken back by HDL)

80
Q

What is the adipose, heart , muscle, live distribution of chylomicrons?

A

80% - adipose, heart, muscle

20% - liver

81
Q

Apolipoproteins associated with:
chylomicron
VLDL

A

ApoB48 (and ApoCII, ApoE from HDL)

ApoB100 (and ApoCII, ApoE from HDL)

82
Q

Which lipid is highest in cholesteryl esters?

highes in protein/lipid ratio?

A

LDL

HDL

83
Q

What does HMG CoA reductase do and what downregulates its actions?

A

makes cholesterol in the liver

LDL binding liver downregulates

84
Q

How is saturated fat interference at the HDL binding site at the liver a double whammy?

A

Cholesterol remains in blood

more cholesterol made in liver because HMG CoA reductase keeps churning out cholesterol

85
Q

Where are the exceptions to fat being the dominant form of energy?

A

Brain and RBC’s

86
Q

When does ketogenesis take place?

A

When Acetyl CoA is high and Oxaloacetate is low

87
Q

What makes and uses ketone bodies?

not really ketones, but organic acids that drop pH

A

Liver makes but does NOT use.

Everything else uses.

88
Q

What favors ketogenesis?

A

low insulin/glucagon ratio

a lot of glucagon

89
Q

When you’re hungry, what stimulates the liver for GNG?

what stimulates the cells for TAG breakdown?

A

Glucagon talks to the liver

Epinepherine talks to the cells

90
Q

What does PKA, from the Adenelyate Cyclase pathway, activate by phosphorylation?

A

Breakdown of TAG to DAG

then other lipases break down further

91
Q

What is the initial effector of the Adenelyate Cyclase pathway leading to TAG breakdown?

A

Hormone (glucagon and epinepherine)

This is a Hormone Sensitive Lipase

92
Q

What is the fate of released glycerol in TAG breakdown?

A

Liver GNG or glycolysis

both in liver

93
Q

In the cell, where does building and breaking down fat occur?

A

Build - in cell

Break down - in mitochondria

94
Q

Trace fat changes from outside the cell to the mitochondrial matrix.

A

TAG outside > lipoprotein lipase breaks to FFA > FA inside cell > Fatty acyl CoA (via FACS) > Acyl Carnitine (crosses into mitochondria) > Fatty acyl CoA

Beta oxidation from here

95
Q

What size Fatty Acids go through the Carnitine Cycle to enter the mitochondria?

Where do they go if they’re bigger?

A

12-20

Peroxisome

96
Q

What inhibits carnitine acyltransferase (CPT-1) from transfering Fatty acyl residues to acyl carnitine?

A

Malonyl CoA

a substrate of fat synthesis

97
Q

What is exchanged in a 1:1 ratio through a translocase at the IMM?

A

Fatty acyl carnitine for carnitine

98
Q

Once in the Matrix, what is responsible for changing Fatty acyl carnitine back to Fatty acyl CoA

A

Carnitine Acyltransferase II (CPT-II)

99
Q

What does Palmitate (16:0) yield upon Beta-Oxidation?

A

8 Acetyl CoA
7 NADH
7 FADH2
7 H+

100
Q

What does each turn of Beta Oxidation yield?

A

1 Acetyl CoA
1 NADH
1 FADH2

(each pass takes off 2 Carbons)

101
Q

What is the first step (most important) Enzyme in Beta-Oxidation?

A

acyl-CoA dehydrogenase

102
Q

Where are very long chain FA catabolized?

A

Peroxisomes

103
Q

What are the final products in Long Chain Fatty Acid Oxidation?
Are NADH and FADH2 produced in this process?

A

Octanoyl CoA
Acetyl CoA
(both metabolized in mitochondria)

no

104
Q

What enzyme changes H2O2 to Water and oxygen in the peroxisome?

A

Catalase

105
Q

What is the odd numbered Fatty acid of metabolism?

What is its coenzyme?

A

Propionyl CoA

B12 (biotin)

106
Q

How are unsaturated fatty acids metabolized?

A

Isomerized, Oxidized, and miss the first redox rxn

107
Q

What are unsaturated fatty acids isomerized to?

A

Trans (delta 2) Enoyl CoA

then oxidized

108
Q

What is the most important (for this class) ketone body?

A

D-3-Hydroxybutarate

109
Q

What are the 3 ketone bodies?

Where are they made?

A

Acetoacetate (this makes two products, which are)

Acetone
D-3-Hydroxybutarate

Made exclusively in the liver (these are basically mobile acetyl CoA)

110
Q

What does uncontrolled ketone body formation lead to?

A

Ketoacidosis

111
Q

What is the starting product of Ketogenesis and where does it occur?

A

2 Acetyl CoA’s

Liver only

112
Q

Where does Fatty Acid synthesis occur?

organs and location in cell

A

Liver and lactating mammary glands

Cytosol

113
Q

How many Acetyl Coa does it take to make Palmitate?

A

8

114
Q

Where is the Acetyl CoA used in palmitate synthesis produced?
Where is it used?

A

Produced in the mitochondria

Used in the cytosol

115
Q

How does Acetyl CoA get out of the mitochondrial matrix to undergo fatty acid synth?

A

Combines with oxaloacetate to form Citrate.

Citrate leaves the Mitochondria

Once in the cytosol, citrate breaks down into oxaloacetate and Acetyl CoA (and uses 1ATP in the process - there’s your skin in the game)

116
Q

What pathway provides NADPH for FA synth?

A

Pentose Phosphate Pathway

117
Q

What are the 2 stages of FA synth and what is the (important) committed step?

A

Stage 1: Acetyl CoA (via Acetyl CoA Carboxylase) > Malonyl CoA
(this is the committed step)

Stage 2: Elongation (2C increments)

118
Q

What is the committed step for FA biosynth?

What prosthetic group and other ingredient is required for this step?

A

Acytel CoA Carboxylase rxn

Biotin (Vita B7) and bicarbonate

119
Q

What does Acetyl CoA carboxylase do to Acetyl CoA?

What does it yield?

A

Adds a Caboxyl group
(with biotin/B7 prosthetic group and at the expense of 1 ATP)

Malonyl CoA

120
Q

T/F

FA synth requires a carboxylation using CO2 then a decarboxylation

A

True

121
Q

What allosterically regulates Acetyl CoA carboxylase?

A

Citrate (turns on)

Palmitoyl CoA (turns off)

122
Q

What hormonally regulates Acetyl CoA carboxylase?

A

Insulin (via protein phophatase) turns on

Glucagon (via cAMP dependent protein kinase) turns off

123
Q

What dephosphorylates (and activates) Acetyl CoA carboxylase?

A

PP2A

124
Q

What causes the protomers of Acetyl CoA carboxylase to polymerize?
What allosterically inhibits this process?

A

Citrate or Isocitrate

Malonyl CoA and Palmitoyl CoA

125
Q

What are the required inputs for the synthesis of Palmitate?

A

8 Acetyl CoA
7 ATP
14 NADHP (remember, this comes from the PPP)

126
Q

What is the main factor controlling the rate of lipogenesis?

A

The amount of enzyme, which is controlled by nutritional state

127
Q

When are rates of FA synth greatest and lowest?

A

High carb/low fat meal

starvation (or a high fat diet)

128
Q

What enzyme controls FA elongation?

Where does this occur?

A

Fatty Acid elongase

ER

129
Q

Where does Fatty Acid desaturation occur?

What enzyme is used?

A

ER

Fatty Acyl CoA desaturase

130
Q

What is the direct building block (two carbon donor) to FA synth?

A

Malonyl CoA

131
Q

What is the common intermediate between Triacylglycerol and Phospholipids?

A

Phosphatidate

this matters because the glycerol comes from TAG breakdown to make Glycerol-3-P > Phosphatidate

132
Q

Why are TAG’s only made in adipose if glucose is available?

What is the molecule involved?

A

Unlike the liver, the source of glycerol comes from the glycolytic pathway

dihydroxyacetone phosphate (this generates glycerol-3-P)

133
Q

How is pyruvate returned to the mitochondria in FA synth?

A

Pyruvate > Oxaloacetate + Acetyl CoA = Citrate
Citrate leaves mito
Citrate > Acetyl CoA + Oxaloacetate

Oxaloacetate > Malate and back through Mitochondria

134
Q

Where does cholesterol synthesis occur?

A

Cytosol (all 4 phases)

Mostly in the Liver

135
Q

What do 3 Acetyl CoA’s come together to form in Cholesterol biosynthesis?
Where does the NADPH come from in this rxn?

A

Mevalonate (6C)

PPP

136
Q

What is the key regulatory enzyme in Cholesterol biosynthesis?
What step?

A

HMG CoA reductase

HMG CoA > Mevalonate (step 3)

137
Q

1st 3 steps in Cholesterol biosynthesis:

A

Acetyl CoA + Acetyl CoA > Acetoacetyl CoA + Acetyl CoA > HMG CoA (NADPH>NADP+) > Mevalonate

138
Q

What does Mevalonate form in phase II (with multiple steps) of Cholesterol synthesis?

A

Isoprenoid

139
Q

Outline Phase 2 of cholesterol synthesis:

A

Mevalonate > 3 Phosphorylations/1 decarboxylation

Isoprenoid

140
Q

What are the 2 types of Isoprenoids made in phase II of cholesterol synthesis?

A 
Isopentenyl pyrophosphate (IPP)
Dimethylallyl pyrophosphate (DPP)
141
Q

Where do all Carbon atoms in cholesterol originally come from?

A

Acetyl CoA

142
Q

Phase 3 cholesterol synthesis:

A

Isoprenoids condense to Squalene (30C)

143
Q

How many Carbons are in cholesterol?

A

27

144
Q

Outline phase 4 of cholesterol synthesis:

A

Squalene circularized to Lanosterol

Lanosterol > Cholesterol

145
Q

What suppresses HMG CoA reductase?

A

LDL take-up by the liver

146
Q

HMG CoA in the mitochondria is used for?

HMG CoA in the cytosol is used for?

A

mito - makes ketone bodies

cytosol - makes cholesterol

147
Q

The main enzyme (and rate limiting step) in the cytosol is HMG CoA reductase.
What is the enzyme in the mitochondria that makes ketone bodies from HMG CoA?

A

HMG CoA Lyase

148
Q

How does HMG CoA make ketone bodies in the mitochondria?

A

loses Acetyl CoA to form acetoacetate

acetoacetate > D-Beta hydroxybutarate
and acetone

149
Q

Name two polar derivatives of cholesterol.

A

Bile Salts

Glycocholate and Taurocholate

150
Q

What are the 4 main classes of steroids derived from cholesterol and what are their precursors?

A

cholesterol > pregnenolone > progestagens

glucocorticoids
mineralocorticoids
androgens
estrogens

151
Q

What is the precursor to Vitamin D?

A

cholesterol

152
Q

What is the intermediate from which TAG’s or phospholipids are formed?

A

Phosphatidate

diacylglyceride

153
Q

TAG synthesis pathway:

A

Glycerol-3-Phosphate > lysophosphatidic acid > phosphatidate > DAG > TAG

154
Q

Phosphatidate + CTP >

A

CDP - diacylglycerol

155
Q

What eicosanoid is derived from omega-6?

omega-3?

A

Arachidonic

Eicosapentanoic (EPA)

156
Q

What are the key eicosanoid enzymes?

A

cyclooxengenase (COX)

lipooxygenase (LOX)

157
Q

T/F

omega 6 and 3’s are both MUFA’s that act as paracrine and autocrine messenger molecules.

A

False

PUFA

158
Q

What is the key enzyme in the production of prostaglandin?

A

COX

159
Q

What is the key enzyme that makes thromboxane?

A

thromboxane A synthase

Tim's Cards (140 decks)

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