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Biochem 2 > Biochem 2 Ex 2 > Flashcards

Biochem 2 Ex 2 Flashcards

1
Q

What is the storage form of carbohydrate?

A

glycogen

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2
Q

Which is bigger, proglycogen or macroglycogen?

A

macroglycogen

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3
Q

Which form of glycogen is more sensitive to dietary carbohydrate?

A

proglycogen

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4
Q

Which form of glycogen is synthesized more rapidly following post exercise glycogen depletion?

A

proglycogen

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5
Q

When does post exercise synthesis of proglycogen reach a plateau?

A

after 24 hours

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6
Q

Which form of glycogen is synthesized slowly and constantly?

A

macroglyocgen

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7
Q

When does synthesis of macroglycogen occur?

A

for at least 48 hours post exercise

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8
Q

Which form of glycogen is responsible for carb loading?

A

macroglycogen

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9
Q

What is the storage form of glucose in animals?

A

glycogen

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10
Q

What bonds are most frequent in glycogen?

A

a1,4

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11
Q

What type of bonds are a1-4 and a1-6 bonds?

A

glycosidic bonds

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12
Q

What bond forms the branches of glycogen?

A

a1,6 bonds

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13
Q

How many bonds in glycogen are a1-6?

A

1 out of about 10

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14
Q

What is the purpose of branching in glycogen?

A

increases solubility and gives it more accessible surface area to “eat”

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15
Q

What is the first carbon in D-Glucose?

A

the one double bonded to O and single bonded to one H

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16
Q

What is the first carbon in a-D-Glucopyranose?

A

to the right and down to the O

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17
Q

Where does an a1-4 bond take place?

A

between the 1 carbon of a glucose and the 4 carbon of another

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18
Q

What are the two types of starch?

A

amylose and amylopectin

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19
Q

Is amylose branched or unbranched?

A

unbranched

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20
Q

What bond takes place in amylose?

A

a1-4

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21
Q

Is amylopectin branched or unbranched?

A

branched

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22
Q

What bonds take place in amylopectin?

A

a1-4 and a1-6

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23
Q

How often do we see an a1-6 bond in amylopectin?

A

every 30 a1-4 bonds

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24
Q

How much glycogen is stored in skeletal muscle?

A

400 grams

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25
Q

How much glycogen is stored in the liver?

A

100 grams

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26
Q

How much glycogen is stored in other cells?

A

small quantities

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27
Q

Where is glycogen stored in the cell?

A

cytosol

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28
Q

Why is glucose trapped in muscle?

A

it lacks the enzyme needed to release glucose

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29
Q

How much glucose is not fully accessible during exercise?

A

about 1600 kcal

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30
Q

What is the first step of glycogen synthesis initiation?

A

glucose is turned into glucose-6 phosphate

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31
Q

What is the second step of glycogen synthesis initiation?

A

glucose-6 phosphate is converted into glucose 1 phosphate

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32
Q

What is the third step of glycogen synthesis initiation?

A

glucose-1 phosphate is combined with UTP, forming UDP Glucose

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33
Q

What is used to initiate a chain of glycogen?

A

glycogenin

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34
Q

What is glycogenin?

A

a protein that starts the glycogen chain with the amino acid tyrosine

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35
Q

What enzyme initiates a glycogen chain?

A

glycogen initiator synthase

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36
Q

What enzyme adds glucose moleules to a glycogen chain?

A

glycogen synthase

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37
Q

What bond does glycogen synthase use to add a glucose molecule to a glycogen chain?

A

a1-4

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38
Q

Where does elongation of the glycogen chain take place?

A

cytosol

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39
Q

What enzyme is used in glycogen branching?

A

glucosyl 4:6 transferase

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40
Q

How does glucosyl 4:6 transferase work?

A

takes 5-8 carbon chains from the end and attaches them to another glucose molecule in the chain

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41
Q

What bond does glucosyl 4:6 transferase use?

A

a1-6

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42
Q

What are the advantages of branching in glycogen?

A

many ends, increases rates of synthesis and degradation, more soluble molecule

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43
Q

What enzyme degrades glycogen?

A

glycogen phosphorylase

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44
Q

What is the product of glycogen phosphorylase?

A

Glucose 1 phosphate

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45
Q

What enzyme converts glucose 1 phosphate to glucose 6 phosphate?

A

phosphoglucomate

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46
Q

Where does the glucose 6 phosphate from glycogen degradation go?

A

glycolysis and pentose phosphate pathway

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47
Q

What is the regulatory enzyme in glycolysis?

A

phosphofructokinase

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48
Q

When does glycogen phosphorylase become ineffective?

A

when there are four glucose molecules left prior to a branch point

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49
Q

What two enzymes are required to break down the end of the branches of glycogen?

A

glucosyl 4:4 transferase and amylo-a-1,6-glucosidase

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50
Q

What is the function of glucosyl 4:4 transferase?

A

removes the three glucose molecule prior to the last glucose of the branch

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51
Q

What is the function of amylo-a-1,6-glucosidase?

A

removes the last glucose of the branch

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52
Q

Why is calcium important for glycolysis?

A

calcium’s presence indicates muscle activity and a need to have glucose for glycolysis

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53
Q

What is the key enzyme responsible for the synthesis of glycogen?

A

glycogen synthase

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54
Q

Where is glycogen synthase bound?

A

to part of the glycogen protein complex

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55
Q

How is glycogen synthase released?

A

it is bound to part of the glycogen protein complex, when glycogen concentration decreases, it is released

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56
Q

What is gluconeogenesis?

A

synthesis of glucose from non-carbohydrate precursors

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57
Q

What is the pathway of gluconeogenesis?

A

pyruvate to glucose

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58
Q

What are the main entry points of gluconeogenesis?

A

pyruvate, oxaloacetate, and DHAP

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59
Q

What are the main non-carbohydrate precursors of gluconeogenesis?

A

lactic acid, amino acids, and glycerol

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60
Q

What parts of the body require glucose?

A

brain, red blood cells, testes, medulla of the kidney, cornea of the eye, and muscle

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61
Q

Can we reverse glycolysis?

A

no, energetically unfavorable

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62
Q

Where does gluconeogenesis take place?

A

liver and kidney

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63
Q

What % of gluconeogenesis takes place in the liver?

A

90%

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64
Q

What % of gluconeogenesis takes place in the kidney?

A

10%

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65
Q

What is needed to make gluconeogenesis favorable?

A

use alternative enzymes, couple the reactions to energy liberating reactions, and use ATP or the equivalent

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66
Q

What are the enzymes responsible for the irreversible reactions of glycolysis?

A

hexokinase, phosphofructokinase, and pyruvate kinase

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67
Q

Where do we find pyruvate carboxylase?

A

in the mitochondria of liver and kidney

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68
Q

What are the substrates of gluconeogenesis?

A

glycerol, lactic acid, and a-ketoacids

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69
Q

What is glycerol?

A

the backbone of triglycerides

70
Q

What is lactic acid?

A

waste product of glycolysis

71
Q

What are a-ketoacids?

A

pyruvate, OAA,a-keoglutarate

72
Q

Where are a-keto-acids derived from?

A

glycogenic amino acids

73
Q

What is the direct precursor to PEP?

A

OAA

74
Q

Is glycerol fat?

A

no

75
Q

Can glycerol be converted into glucose?

A

yes

76
Q

Is glycerol a major source of making glucose?

A

no

77
Q

What is a significant substrate for gluconeogenesis during exercise?

A

lactate

78
Q

Where is lactate released from?

A

working muscle

79
Q

What organ takes lactic acid to create glucose?

A

the liver

80
Q

What is the Cori Cycle?

A

The muscle takes Glucose 6 Phosphate ->pyruvate ->lactate, which goes to the liver, -> pyruvate -> glucose, which goes to the blood stream

81
Q

Does exercise raise or lower blood glucose?

A

lowers

82
Q

What stimulates gluconeogenesis in the liver?

A

glucagon

83
Q

Where is the carbonyl group on an alpha ketoacid?

A

alpha carbon

84
Q

What are alpha ketoacids usually created from?

A

amino acids

85
Q

What stimulates the conversion of amino acids into glucose?

A

starvation or low carb intake

86
Q

Before an amino acids becomes glucose, what does it become first?

A

alpha ketoacid

87
Q

What is the primary source of glucose from gluconeogenesis when at rest?

A

alpha ketoacids

88
Q

Where do most alpha ketoacids come from?

A

the breakdown of amino acids

89
Q

What are the non-essential glucogenic amino acids?

A

alanine, asparagine, aspartate, cysteine, glutamate, glutamine, glycine, proline, serine, tyrosine

90
Q

What are the essential glucogenic amino acids?

A

arginine, histidine, isoleucine, methionine, phenylalanine, threonine, valine, tryptophan

91
Q

What is the glucose-alanine cycle?

A

(in muscle) glycogen -> glucose 6 phosphate -> pyruvate -> (amino acids in, keto acids out) -> alanine (to the liver) -> pyruvate (NH3 ->Urea) -> glucose (to the blood stream)

92
Q

When does the glucose alanine cycle take place?

A

primarily during exercise, when glycolysis is running fast

93
Q

What is the difference between alanine and pyruvate?

A

the NH3 from alanine is removed and replaced by =O

94
Q

What is ketosis usually in response to?

A

gluconeogenesis

95
Q

What is ketosis?

A

an elevation in ketones in blood and urine

96
Q

What can ketones be made into when oxidized?

A

ATP

97
Q

What are ketones primarily created from?

A

fat

98
Q

What does ketosis spare?

A

amino acids

99
Q

What are some examples of common ketones?

A

acetoacetate, beta hydroxybutyrate, and acetone

100
Q

What make ketone bodies?

A

acetyl CoA or things that can turn into acetyl CoA

101
Q

What turns into acetyl CoA?

A

fat (through OHOT)

102
Q

Can acetyl CoA turn into glucose?

A

no

103
Q

What is the entry point into the Kreb’s cycle?

A

acetyl-CoA

104
Q

Is fat burning increased or decreased in response to low carbohydrate?

A

increase

105
Q

In ketosis, does the body use the ketones or glucose?

A

ketones

106
Q

What diminishes gluconeogenesis?

A

ketosis

107
Q

Where is insulin found?

A

beta cells of the pancreas

108
Q

What does insulin do?

A

lowers blood sugar and stimulates glycogen formation

109
Q

Does insulin inhibit or stimulate gluconeogenesis?

A

inhibits

110
Q

Where is glucagon found?

A

alpha cells of the pancreas

111
Q

What does glucagon do?

A

elevates blood sugar and stimulates glycogen breakdown

112
Q

Does glucagon inhibit or stimulate gluconeogenesis?

A

stimulates

113
Q

What is the cheerleader for glycolysis?

A

fructose 2,6 - bisphosphate

114
Q

What does fructose 2,6-bisphosphate activate?

A

PFK in the liver

115
Q

What does PFK in the liver do?

A

increases affinity for fructose 6 phosphate, decreases the inhibiting effect of ATP, and is an allosteric activator

116
Q

Does eating fat stimulate fat synthesis?

A

no

117
Q

What stimulates fat synthesis?

A

eating lots of sugar

118
Q

What transport protein take glucose, fructose and galactose from the intestine to the liver?

A

GLUT2

119
Q

Which transport protein in insulin dependent?

A

GLUT2

120
Q

What transport protein takes glucose into muscle and adipose tissue?

A

GLUT4

121
Q

Is GLUT4 stimulated by insulin?

A

yes

122
Q

What transport protein is stimulated by low energy charge?

A

GLUT4

123
Q

What transport protein moves via facilitated diffusion?

A

GLUT4

124
Q

What does it take for glucose to move from the blood to the muscle?

A

for the concentration of glucose to be lower in the muscle

125
Q

What keeps glucose flowing into the muscle?

A

adding a phosphate to glucose in the muscle

126
Q

When muscle glycogen is low, what gets converted to glycogen?

A

glucose 6 phosphate

127
Q

Where does glucose go when muscle glucose and glycogen is full?

A

liver

128
Q

Is glucokinase inhibited by its product?

A

no

129
Q

What stimulates glucokinase?

A

stimulated by insulin

130
Q

Where does synthesis of fatty acids take place?

A

liver, adipose tissue and kidney (to a lesser extent), mammary glands during lactation

131
Q

Where does synthesis of fatty acid occur in the cells?

A

cytosol

132
Q

What is the mechanism for the building of fatty acids?

A

incorporation of 2 carbon molecules (acetyl), NADPH provides reducing power, ATP is consumed

133
Q

What two molecules are needed to start the process of fatty acid synthesis?

A

acetyl CoA (2 Cs), malonyl CoA (3 Cs)

134
Q

What is malonyl made from?

A

acetyl

135
Q

Where do acetyl and malonyl need to be for fatty acid synthesis?

A

cytosol

136
Q

What are the 3 parts of the mechanism of fatty acid synthesis?

A

get acetyl to cytosol, make malonyl CoA, build the fatty acid (fatty acid synthase, CRDR)

137
Q

What makes acetyl CoA?

A

oxidation of pyruvate

138
Q

Where does oxidation of pyruvate take place?

A

mitochondria

139
Q

When does oxidation of pyruvate take place?

A

when citrate levels are high

140
Q

When do citrate levels elevate?

A

when Isocitrate Dehydrogenase is inhibited

141
Q

What inhibits Isocitrate Dehydrogenase?

A

high levels of ATP

142
Q

What does fatty acid synthesis require?

A

high ATP

143
Q

What stimulates Acetyl CoA carboxylase?

A

citrate and insulin

144
Q

What inhibits Acetyl CoA carboxylase?

A

malonyl CoA, Palmitol CoA (end product), and epinephrine

145
Q

What is Acetyl CoA Carboxylase?

A

a protein

146
Q

What increases the synthesis of Acetyl CoA Carboxylase?

A

High carb diets, low fat diets

147
Q

What decreases the synthesis of Acetyl CoA Carboxylase?

A

high fat diets, fasting

148
Q

What is fatty acid synthase?

A

a multienzyme complex

149
Q

What is ACP?

A

Acyl Carrier Protein

150
Q

What are the seven steps of ACP?

A

ACP grabs acetyl, ACP transfers acetyl to a holding site, ACP grabs malonyl, acetyl and malonyl combine (decarboxylation, 2+3=4), Ketone is converted into an alcohol (NADPH reduction), water is removed (double bond), molecule is reduced (NADPH)

151
Q

Where does the growth on ACP stop?

A

16 carbons (Palmitate 16:0)

152
Q

What are the four reactions of fatty acid synthase?

A

CRDR - condenses(+2C), reduces(NADPH), dehydrates, and reduces(NADPH)

153
Q

Where is NADPH created?

A

pentose phosphate pathway

154
Q

What is the source of reducing power in synthesis?

A

NADPH

155
Q

What molecules are highly reduced?

A

fatty acids

156
Q

What can palmitate be?

A

elongated and desaturated

157
Q

What enzymes elongate?

A

elongases

158
Q

What enzymes desaturate?

A

desaturases

159
Q

Where do elongation and desaturation take place?

A

mitochondria and endoplasmic reticulum

160
Q

At what carbon can humans not create a double bond?

A

beyond the 9th-10th

161
Q

What are the important steps to fat synthesis?

A

eat sugar, rest, muscle hexokinase is inhibited by glucose 6 phosphate, liver glucokinase is stimulated by glucose and not inhibited by glucose 6 phosphate, liver runs glycolysis, ATP inhibits isocitrate dehydrogenase and stops TCA, citrate spills out and acetyl CoA is given back, Acetyl CoA into Malonyl CoA, fatty acid synthase adds malonyl CoAs(CRDR), Palmitate 16:0

162
Q

What is the primary site of fructose disposal?

A

liver

163
Q

What % of fructose is extracted by the liver on the first pass?

A

50%

164
Q

What % fructose is extracted by the liver?

A

75%

165
Q

What enzymes are essential for fructose metabolism in the liver?

A

fructokinase and triokinase

166
Q

What does fructose skip?

A

the regulation of PFK

167
Q

What conditions stimulate fatty acid synthesis?

A

high energy charge, lots of acetyl CoA, lots of NADH and FADH2, lots of citrate, lots of sugar (glucose and fructose), insulin

168
Q

What are the key enzymes of fatty acid synthesis?

A

citrate lyase, acetyl CoA carboxylase, and fatty acid synthase (CRDR)

169
Q

What is the product of the condensation step?

A

acetoactyl-ACP

170
Q

What is the product of the 1st reduction step?

A

D-3-hydroxybutyryl-ACP

171
Q

What is the product of the dehydration step?

A

crotonyl-ACP

172
Q

What is the product of the 2nd reduction step?

A

butyryl-ACP

Biochem 2 (4 decks)

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