Lipids Flashcards Preview

NBDE PART 1 BIOCHEM/PHYSIOLOGY > Lipids > Flashcards

Flashcards in Lipids Deck (139):
1

a "standard" fatty acid is an unbranched hydrocarbon chain with a carboxyl group at one end. most naturally occurring fatty acids have _(even/odd) number of carbons.

even

2

the 2 most common fatty acid chain lengths

16 and 18

3

most monounsaturated fats (one double bond) are in cis/trans form

cis

4

omega 3 and omega 6 are essential/non essential fatty acids

essential bc we cannot put double bonds in certain positions

5

The fatty acids have two ends, the carboxylic acid (-COOH) end, which is considered the beginning of the chain, thus ___, and the methyl (CH3) end, which is considered the "tail" of the chain, thus "omega

"alpha" = beginning
methyl = end/tail =omega

6

omega 3 fatty acid means

the first double bond, counted from the methyl end, that is, the omega (ω-) or the n- end = on the 3rd carbon

7

all fatty acids are building blocks for _ and _ and therefore needed for

phospholipids and glycolipids
synthesis of membranes

8

cells derive energy from __

fatty acids (beta oxidation)

9

saturated FA/monosaturated/polyunsaturated FA:

1. arachidic acid
2. arachidonic acid

1. saturated = arachidic acid
2. polyunsaturated = arachidonic acid

10

saturated FA/monosaturated/polyunsaturated FA:
linoleic and linolenic acid

polyunsaturated

11

the 3 polyunsaturated FA are

arachidonic acid
linoleic and linolenic acid

12

linolenic is omega?

linole-n-ic is omega 3 bc n looks like 3 if you turn it.

linoleic is omega 6

13

saturated FA/monosaturated/polyunsaturated FA:
stearic acid

saturated

14

saturated FA/monosaturated/polyunsaturated FA:

1. palmitic acid
2. palmitoleic acid

1. palmitic = saturated
2. palmitoleic = monosaturated

15

saturated FA/monosaturated/polyunsaturated FA:

oleic acid

monosaturated

16

butyric acid
myristic acid
caprylic acid are
saturated FA/monosaturated/polyunsaturated FA:

saturated

17

3 monosaturated FA

erucic acid
oleic acid
palmitoleic acid (POE)

18

to remember the saturated FA just remember which acids are polyunsaturated and monounsaturated (6total), all the rest are

saturated

19

you can synthesize arachidonic acid from

linoleic acid (omega-6)

20

what 2 polyunsaturated fatty acids are nutritionally essential

linoleic and linolenic (omega 6 and 3)

21

bile salts are reabsorbed in the __

distal ileum via Na+/bile acid

22

bile salts are recycled by the

liver

23

bile salts are resecreted into the

gut

24

_% of bile salts are recycled

95%

25

bile salts are conjugated in amide linkages by what amino acids?

glycine or taurine

26

which cholic acid conjugates with glycine

glycocholate

27

which cholic acid conjugates with taurine

taurocholate

28

does sphingomyelin contain glycerol

no

29

most membrane phospholipids contain glycerol except

sphingomyelin

30

the membrane phosphlipids that contain glycerol are

lecithin, cerbroside and cardiolipin

31

___ are phospholipids that upon hydrolysis yield 2FA + glycerol + phosphoric acid and choline

lechithin

32

lecithins are _ solube emulsifiers and membrane constituents

water

33

cephalins are phospholipids having _ properties and found especially in nervous tissue of brain and spinal cord.

hemostatic

34

cephalins resemble lecithins except they contain

either 2-ethanolamine or L-serine in place of choline

35

sphingomyelins = phospholipids found especially in nerve tissue and yield

sphingosine, choline, FA, phosphoric acid upon hydrolysis

36

accumulation of sphingomyelins in CNS tissue is associated with _ disease

Niemann-Picks

37

place in order from high density to low density:
HDL, VLDL, chylomicron, LDL

HDL > LDL > VLDL > CHYLOMICRON

38

since lipids are less dense than proteins, there is an inverse relationship b/w lipids and density. the higher the lipid content, the _ the density

lower

39

cholesterol and triglycerides are not able to move in body fluids bc hydrophobic so they are packaged into

lipoproteins

40

the least dense lipoprotein is

chylomicron = most triglyceride content and least protein content

41

chylomicrons transport

triglycerides from GI to muscle, adipose and liver

42

VLDLs

more dense than chylomicrons, have high content of triglycerides.

43

VLDL's transport __ triacylglycerides from the liver to various tissues

endogenous

eat fat --> chylomicron leaves GI --> liver --> liver breaks it down, make VLDL --> sends it to tissues

44

which has highest content of cholesterol?
HDL, LDL, chylomicron or VLDL

LDL

45

the primary plasma carriers of cholesterol are

LDL's

46

the most dense lipoprotein is

HDL = lowest triglyceride and highest protein carrier

47

which transfers cholesterol from tissue back to live

HDL

48

VLDL particles are the precursors of _ in circulation

LDL

49

chylomicrons carry

FA obtained from diet to tissues where they are consumed or stored as fuel

50

the remnants of chylomicrons (after delivering the FA triacylglycerols) but still containing cholesterol go to the

liver
taken up, degraded in lysosome and recycled

51

lipoproteins are _ binding proteins

lipid

52

which are protein rich:
HDL, LDL, VLDL, chylomicron

HDL == very little free cholesterol

53

HDL particles are produced __ in the liver

DE NOVO

54

HDL and LDL have their own specific binding sites on cell membranes: HDL on _ and LDL on

HDL = liver
LDL = liver and extrahepatic tissues

55

Lovastatin drug action

Lovastatin = "statin" drug = lowers blood cholesterol levels by inhibiting HMG CoA reductase the enzyme in cholesterol biosynthesis

56

ketone bodies formed only in the

liver

57

the 3 ketone bodies are

acetone (non metabolizable side product)
beta-hydroxybutyrate
acetoacetate

58

first step of ketone production is the synthesis of

acetoacetyl-CoA

59

second step of ketone production

add a third molecule of acetyl-CoA ==> 3hydroxy-3-methylglutaryl CoA (HMG CoA) = enzyme HMG-CoA synthase

60

HMG-CoA synthase is the rate limiting step in ketone bodies synthesis and is only found in the

liver

61

1. HMG-CoA synthase used in
2. HMG-CoA reductase used in

1. ketone body synthesis
2. cholesterol synthesis

62

3rd step of ketone body formation HMG-CoA is cleaved to form

acetoacetate and acetyl coA = by HMG-CoA lyase

63

ketone bodies are used exclusively by

extrahepatic tissue (heart and skeletal muscle especially)

64

the brain can oxidized fatty acids or ketone bodies

only ketone bodies. Brain cannot use FA

65

extrahepatic tissues convert ketones back to acetyl CoA by using

succinyl CoA == CoA donor
and thiophorase enzyme

66

liver cannot use ketone bodies because it lacks

thiophorase enzyme

67

ketone bodies are formed in the __ and can't be used by the __

liver, liver

68

the major source of acetyl CoA for FA synthesis comes from

glucose (when you eat lots of carbs)

69

FA synthesis occurs

primarily in liver and lactating mammary glands, and to lesser extent in kidneys and adipose

70

FA synthesis:
1. glucose degraded to pyruvate by glycolysis in the
2. pyruvate is transported to mitochondria to form _ using what enzyme

1. cytoplasm
2. Acetyl-CoA
pyruvate dehydrogenase ==> acetyl-CoA
PDH decarboxylates pyruvate from 3 c to 2c by losing CO2

71

FA synthesis:
1. Acetyl-CoA is converted to _ inside the mitochondria so that it can move out into the cytoplasm via the ___ shuttle
2. in the cytosol where FA synthesis takes place, citrate is broken down into

1. citrate
citrate-malate-pyruvate shuttle
2. acetyl-CoA

72

Summary of FA synthesis

acetyl CoA --> Malonyl CoA --> Malonyl ACP -->Acetyl ACP -->Acetoacetyl ACP --> Butyryl ACP --> FA

73

the carboxylation of acetyl CoA to form malonyl CoA is catalyzed by

acetyl-CoA carboxylase = allosteric enzyme and principal regulator of FA synthesis

74

Malonyl CoA is a 3 carbon intermediate involved in FA breakdown/synthesis?

synthesis only

75

which is involved in both FA catabolism and anabolism:
malonyl CoA
coenzyme A
carnitine
alcohol dehydrogenase

coenzyme A

76

carnitine is involved in FA catabolism or anabolism:

catabolism
FA taken into mitochondria

77

__ are the predominant source of ATP for moderate levels of activity (lasting longer than 1 hour)

FA

78

1. FA synthesis major tissue site
2. FA degradation major tissue site

1. synthesis liver
2. degradation liver and muscle

79

1. FA synthesis carrier
2. FA oxidation carrier

1. synthesis: citrate (mitochondria to cytosol)
2. oxidation: carnitine (cytosol to mitochondria)

80

which one uses an acyl carrier protein?
FA catabolism or anabolism

synthesis

81

which one uses NADPH
FA catabolism or anabolism

synthesis

82

FA catabolism or anabolism
which one uses NAD+, FAD

oxidation (degradation)

83

1. FA synthesis 2 carbon donor

malonyl CoA donates acetyl CoA

84

FA oxidation 2 carbon donor

acetyl coA

85

activator of FA synthesis

citrate

86

inhibitor of FA synthesis

Fatty acyl CoA

87

inhibitor of beta oxidation

Malonyl CoA

88

product of FA oxidation

acetyl CoA

89

Product of FA synthesis

palmitate

90

ketosis occurs when

fatty acids are incompletely metabolized

91

who gets ketosis

alcoholics DM and fasting/starvation

92

in ketosis do you have more or less potassium in the urine than normal

more

93

is ketoacidosis fatal

only if untreated

94

in a non diabetic how could you reverse ketosis

glucose

95

is acetone (a ketone body) utilized by the body as fuel

no

96

fruity breath is caused by

acetone

97

in a healthy diet, most acetyl CoA is processed thru

TCA

98

during fasting the _ is reduced

TCA cycle activity

99

is FA synthesis a reversal of beta oxidation

no

100

what is a fat (structure)

fat = triglyceride = 3 FA + glycerol

101

which end of the FA is hydrophilic

the head = COOH
end is hydrophobic (tail) hydrocarbons

102

the main component in soap is

FA, heads are soluble in water and tails are soluble in oily dirt = emulsify

103

FA is hydrophilic or hydrophobic

both (ampiphatic)

104

Fats (triglyceride) are hydrophilic or hydophobic

hydrophobic = when the head of FA is attached to glycerol to form fat = becomes hydrophobic

105

Lipids are organic compounds that do/do not dissolve in water?
alcohol?
organic solvents?

dissolve in alcohol and organic solvents but NOT IN WATER

106

the major lipids are

triacylglycerides, phospholipids, steroids

107

which one is the most common lipid
triacylglycerides, phospholipids, steroids

triacylglycerides

108

triglycerides major role:
a. energy source
b. membrane component
c. signal mechanism

a. energy

109

triglyceride is an ester/ether

ester

110

triglycerides provide more than half the energy requirements of the

liver heart and skeletal muscle

111

are triglycerides membrane constituents

no. phospholipids and steroids are!

112

triglycerides contain _ the energy as carbs

2x (9kcal/g) vs carb 4kcal/g

113

glucagon signals the breakdown of TAGs by __ (enzyme)

hormone-sensitive lipase = releases FA

114

place in order of most energy we get
carbs, fats, alcohol, protein

fats (9) > alcohol (7) > carbs and proteins

115

in oxidative metabolism _ is produced and _ is consumed

oxygen consumed
CO2 produced

116

t/f choline is required for synthesis and release of acetylcholine

true

117

t/f choline is also a precursor for synthesis of phospholipids phosphatidylcholine (lecithin) and sphingomyelin

true

118

can choline be synthesized de novo

yes from phosphatidylserine in membranes

119

t/f choline is abundant in food

true

120

a deficiency of choline in the diet can lead to

abnormalities in metabolism of fats and lead to fatty liver disease and eventually hepatic cirrhosis

121

carnitine is req for

transport of FA across mitochondrial membrane - so it is essential in normal fatty acid metabolism

122

is carnitine essential

no bc it can be synthesized de novo. it is considered conditionally essential bc human genetic disorders of carnitine metabolism have been corrected by carnitine supplementation

123

the secretion of glucagon from pancreatic alpha cells is increases 2-3x by hypoglycemia and reduced to __ of the basal release by hyperglycemia.

half

124

unlike insulin, glucagon acts ONLY on the

liver

125

when glucagon and epinephrine activate adenylate cyclase in adipocyte plasma membrane = cAMP increases = activates protein kinase = phosphorylates hormone sensitive TAG lipase which

is now activated = lipolysis

126

glycerol released by TAG lipase is phosphorylated by glycerol kinase ==> glycerol 3 phosphate. this is then oxidized to dihydroxyacetone phosphate and then to __ to enter glycolysis

Glyceraldehyde 3 phosphate (GAP)

127

insulin activation of phosphorylase which dephosphorylates hormone sensitive lipase causes

lipolysis to stop

128

electron transport chain reaction is

(2H+) + (2e-) + (1/2 O2) ==> H20 + energy

129

electron transport chain reaction is __thermic

exo

130

electron transport chain reaction energy released is coupled with the formation of _ATP molecules per every use of the chain

3

131

in TCA 4 reactions transfer electrons to

NAD+ or FAD+ ==> NADH + FADH2 ==> enter electron transport chain reaction and become oxidized

132

each turn in TCA gives you:
_CO2
_ GTP
_NADH
_FADH2

2 CO2,
1GTP
3NADH
1FADH2

133

the NADH and FADH2 oxidized in the electron transport chain reaction give you _ATP

10

134

TCA occurs in the

mito

135

electron transport chain reaction occurs in

inner mito membrane

136

glycolysis occurs in

cytosol

137

do rbc have electron transport chain reaction

no bc no mitochondria

138

electron transport chain reaction is made up of electron

carriers (flavoproteins, iron-sulfur proteins, coenzyme Q and cytochromes)

139

during ox phosphorylation the __ created using energy from the e- transport chain is used to produce ATP

proton gradient