Biochem 2 Ex 2 Flashcards
(172 cards)
1
Q
What is the storage form of carbohydrate?
A
glycogen
2
Q
Which is bigger, proglycogen or macroglycogen?
A
macroglycogen
3
Q
Which form of glycogen is more sensitive to dietary carbohydrate?
A
proglycogen
4
Q
Which form of glycogen is synthesized more rapidly following post exercise glycogen depletion?
A
proglycogen
5
Q
When does post exercise synthesis of proglycogen reach a plateau?
A
after 24 hours
6
Q
Which form of glycogen is synthesized slowly and constantly?
A
macroglyocgen
7
Q
When does synthesis of macroglycogen occur?
A
for at least 48 hours post exercise
8
Q
Which form of glycogen is responsible for carb loading?
A
macroglycogen
9
Q
What is the storage form of glucose in animals?
A
glycogen
10
Q
What bonds are most frequent in glycogen?
A
a1,4
11
Q
What type of bonds are a1-4 and a1-6 bonds?
A
glycosidic bonds
12
Q
What bond forms the branches of glycogen?
A
a1,6 bonds
13
Q
How many bonds in glycogen are a1-6?
A
1 out of about 10
14
Q
What is the purpose of branching in glycogen?
A
increases solubility and gives it more accessible surface area to “eat”
15
Q
What is the first carbon in D-Glucose?
A
the one double bonded to O and single bonded to one H
16
Q
What is the first carbon in a-D-Glucopyranose?
A
to the right and down to the O
17
Q
Where does an a1-4 bond take place?
A
between the 1 carbon of a glucose and the 4 carbon of another
18
Q
What are the two types of starch?
A
amylose and amylopectin
19
Q
Is amylose branched or unbranched?
A
unbranched
20
Q
What bond takes place in amylose?
A
a1-4
21
Q
Is amylopectin branched or unbranched?
A
branched
22
Q
What bonds take place in amylopectin?
A
a1-4 and a1-6
23
Q
How often do we see an a1-6 bond in amylopectin?
A
every 30 a1-4 bonds
24
Q
How much glycogen is stored in skeletal muscle?
A
400 grams
25
How much glycogen is stored in the liver?
100 grams
26
How much glycogen is stored in other cells?
small quantities
27
Where is glycogen stored in the cell?
cytosol
28
Why is glucose trapped in muscle?
it lacks the enzyme needed to release glucose
29
How much glucose is not fully accessible during exercise?
about 1600 kcal
30
What is the first step of glycogen synthesis initiation?
glucose is turned into glucose-6 phosphate
31
What is the second step of glycogen synthesis initiation?
glucose-6 phosphate is converted into glucose 1 phosphate
32
What is the third step of glycogen synthesis initiation?
glucose-1 phosphate is combined with UTP, forming UDP Glucose
33
What is used to initiate a chain of glycogen?
glycogenin
34
What is glycogenin?
a protein that starts the glycogen chain with the amino acid tyrosine
35
What enzyme initiates a glycogen chain?
glycogen initiator synthase
36
What enzyme adds glucose moleules to a glycogen chain?
glycogen synthase
37
What bond does glycogen synthase use to add a glucose molecule to a glycogen chain?
a1-4
38
Where does elongation of the glycogen chain take place?
cytosol
39
What enzyme is used in glycogen branching?
glucosyl 4:6 transferase
40
How does glucosyl 4:6 transferase work?
takes 5-8 carbon chains from the end and attaches them to another glucose molecule in the chain
41
What bond does glucosyl 4:6 transferase use?
a1-6
42
What are the advantages of branching in glycogen?
many ends, increases rates of synthesis and degradation, more soluble molecule
43
What enzyme degrades glycogen?
glycogen phosphorylase
44
What is the product of glycogen phosphorylase?
Glucose 1 phosphate
45
What enzyme converts glucose 1 phosphate to glucose 6 phosphate?
phosphoglucomate
46
Where does the glucose 6 phosphate from glycogen degradation go?
glycolysis and pentose phosphate pathway
47
What is the regulatory enzyme in glycolysis?
phosphofructokinase
48
When does glycogen phosphorylase become ineffective?
when there are four glucose molecules left prior to a branch point
49
What two enzymes are required to break down the end of the branches of glycogen?
glucosyl 4:4 transferase and amylo-a-1,6-glucosidase
50
What is the function of glucosyl 4:4 transferase?
removes the three glucose molecule prior to the last glucose of the branch
51
What is the function of amylo-a-1,6-glucosidase?
removes the last glucose of the branch
52
Why is calcium important for glycolysis?
calcium's presence indicates muscle activity and a need to have glucose for glycolysis
53
What is the key enzyme responsible for the synthesis of glycogen?
glycogen synthase
54
Where is glycogen synthase bound?
to part of the glycogen protein complex
55
How is glycogen synthase released?
it is bound to part of the glycogen protein complex, when glycogen concentration decreases, it is released
56
What is gluconeogenesis?
synthesis of glucose from non-carbohydrate precursors
57
What is the pathway of gluconeogenesis?
pyruvate to glucose
58
What are the main entry points of gluconeogenesis?
pyruvate, oxaloacetate, and DHAP
59
What are the main non-carbohydrate precursors of gluconeogenesis?
lactic acid, amino acids, and glycerol
60
What parts of the body require glucose?
brain, red blood cells, testes, medulla of the kidney, cornea of the eye, and muscle
61
Can we reverse glycolysis?
no, energetically unfavorable
62
Where does gluconeogenesis take place?
liver and kidney
63
What % of gluconeogenesis takes place in the liver?
90%
64
What % of gluconeogenesis takes place in the kidney?
10%
65
What is needed to make gluconeogenesis favorable?
use alternative enzymes, couple the reactions to energy liberating reactions, and use ATP or the equivalent
66
What are the enzymes responsible for the irreversible reactions of glycolysis?
hexokinase, phosphofructokinase, and pyruvate kinase
67
Where do we find pyruvate carboxylase?
in the mitochondria of liver and kidney
68
What are the substrates of gluconeogenesis?
glycerol, lactic acid, and a-ketoacids
69
What is glycerol?
the backbone of triglycerides
70
What is lactic acid?
waste product of glycolysis
71
What are a-ketoacids?
pyruvate, OAA,a-keoglutarate
72
Where are a-keto-acids derived from?
glycogenic amino acids
73
What is the direct precursor to PEP?
OAA
74
Is glycerol fat?
no
75
Can glycerol be converted into glucose?
yes
76
Is glycerol a major source of making glucose?
no
77
What is a significant substrate for gluconeogenesis during exercise?
lactate
78
Where is lactate released from?
working muscle
79
What organ takes lactic acid to create glucose?
the liver
80
What is the Cori Cycle?
The muscle takes Glucose 6 Phosphate ->pyruvate ->lactate, which goes to the liver, -> pyruvate -> glucose, which goes to the blood stream
81
Does exercise raise or lower blood glucose?
lowers
82
What stimulates gluconeogenesis in the liver?
glucagon
83
Where is the carbonyl group on an alpha ketoacid?
alpha carbon
84
What are alpha ketoacids usually created from?
amino acids
85
What stimulates the conversion of amino acids into glucose?
starvation or low carb intake
86
Before an amino acids becomes glucose, what does it become first?
alpha ketoacid
87
What is the primary source of glucose from gluconeogenesis when at rest?
alpha ketoacids
88
Where do most alpha ketoacids come from?
the breakdown of amino acids
89
What are the non-essential glucogenic amino acids?
alanine, asparagine, aspartate, cysteine, glutamate, glutamine, glycine, proline, serine, tyrosine
90
What are the essential glucogenic amino acids?
arginine, histidine, isoleucine, methionine, phenylalanine, threonine, valine, tryptophan
91
What is the glucose-alanine cycle?
(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
When does the glucose alanine cycle take place?
primarily during exercise, when glycolysis is running fast
93
What is the difference between alanine and pyruvate?
the NH3 from alanine is removed and replaced by =O
94
What is ketosis usually in response to?
gluconeogenesis
95
What is ketosis?
an elevation in ketones in blood and urine
96
What can ketones be made into when oxidized?
ATP
97
What are ketones primarily created from?
fat
98
What does ketosis spare?
amino acids
99
What are some examples of common ketones?
acetoacetate, beta hydroxybutyrate, and acetone
100
What make ketone bodies?
acetyl CoA or things that can turn into acetyl CoA
101
What turns into acetyl CoA?
fat (through OHOT)
102
Can acetyl CoA turn into glucose?
no
103
What is the entry point into the Kreb's cycle?
acetyl-CoA
104
Is fat burning increased or decreased in response to low carbohydrate?
increase
105
In ketosis, does the body use the ketones or glucose?
ketones
106
What diminishes gluconeogenesis?
ketosis
107
Where is insulin found?
beta cells of the pancreas
108
What does insulin do?
lowers blood sugar and stimulates glycogen formation
109
Does insulin inhibit or stimulate gluconeogenesis?
inhibits
110
Where is glucagon found?
alpha cells of the pancreas
111
What does glucagon do?
elevates blood sugar and stimulates glycogen breakdown
112
Does glucagon inhibit or stimulate gluconeogenesis?
stimulates
113
What is the cheerleader for glycolysis?
fructose 2,6 - bisphosphate
114
What does fructose 2,6-bisphosphate activate?
PFK in the liver
115
What does PFK in the liver do?
increases affinity for fructose 6 phosphate, decreases the inhibiting effect of ATP, and is an allosteric activator
116
Does eating fat stimulate fat synthesis?
no
117
What stimulates fat synthesis?
eating lots of sugar
118
What transport protein take glucose, fructose and galactose from the intestine to the liver?
GLUT2
119
Which transport protein in insulin dependent?
GLUT2
120
What transport protein takes glucose into muscle and adipose tissue?
GLUT4
121
Is GLUT4 stimulated by insulin?
yes
122
What transport protein is stimulated by low energy charge?
GLUT4
123
What transport protein moves via facilitated diffusion?
GLUT4
124
What does it take for glucose to move from the blood to the muscle?
for the concentration of glucose to be lower in the muscle
125
What keeps glucose flowing into the muscle?
adding a phosphate to glucose in the muscle
126
When muscle glycogen is low, what gets converted to glycogen?
glucose 6 phosphate
127
Where does glucose go when muscle glucose and glycogen is full?
liver
128
Is glucokinase inhibited by its product?
no
129
What stimulates glucokinase?
stimulated by insulin
130
Where does synthesis of fatty acids take place?
liver, adipose tissue and kidney (to a lesser extent), mammary glands during lactation
131
Where does synthesis of fatty acid occur in the cells?
cytosol
132
What is the mechanism for the building of fatty acids?
incorporation of 2 carbon molecules (acetyl), NADPH provides reducing power, ATP is consumed
133
What two molecules are needed to start the process of fatty acid synthesis?
acetyl CoA (2 Cs), malonyl CoA (3 Cs)
134
What is malonyl made from?
acetyl
135
Where do acetyl and malonyl need to be for fatty acid synthesis?
cytosol
136
What are the 3 parts of the mechanism of fatty acid synthesis?
get acetyl to cytosol, make malonyl CoA, build the fatty acid (fatty acid synthase, CRDR)
137
What makes acetyl CoA?
oxidation of pyruvate
138
Where does oxidation of pyruvate take place?
mitochondria
139
When does oxidation of pyruvate take place?
when citrate levels are high
140
When do citrate levels elevate?
when Isocitrate Dehydrogenase is inhibited
141
What inhibits Isocitrate Dehydrogenase?
high levels of ATP
142
What does fatty acid synthesis require?
high ATP
143
What stimulates Acetyl CoA carboxylase?
citrate and insulin
144
What inhibits Acetyl CoA carboxylase?
malonyl CoA, Palmitol CoA (end product), and epinephrine
145
What is Acetyl CoA Carboxylase?
a protein
146
What increases the synthesis of Acetyl CoA Carboxylase?
High carb diets, low fat diets
147
What decreases the synthesis of Acetyl CoA Carboxylase?
high fat diets, fasting
148
What is fatty acid synthase?
a multienzyme complex
149
What is ACP?
Acyl Carrier Protein
150
What are the seven steps of ACP?
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
Where does the growth on ACP stop?
16 carbons (Palmitate 16:0)
152
What are the four reactions of fatty acid synthase?
CRDR - condenses(+2C), reduces(NADPH), dehydrates, and reduces(NADPH)
153
Where is NADPH created?
pentose phosphate pathway
154
What is the source of reducing power in synthesis?
NADPH
155
What molecules are highly reduced?
fatty acids
156
What can palmitate be?
elongated and desaturated
157
What enzymes elongate?
elongases
158
What enzymes desaturate?
desaturases
159
Where do elongation and desaturation take place?
mitochondria and endoplasmic reticulum
160
At what carbon can humans not create a double bond?
beyond the 9th-10th
161
What are the important steps to fat synthesis?
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
What is the primary site of fructose disposal?
liver
163
What % of fructose is extracted by the liver on the first pass?
50%
164
What % fructose is extracted by the liver?
75%
165
What enzymes are essential for fructose metabolism in the liver?
fructokinase and triokinase
166
What does fructose skip?
the regulation of PFK
167
What conditions stimulate fatty acid synthesis?
high energy charge, lots of acetyl CoA, lots of NADH and FADH2, lots of citrate, lots of sugar (glucose and fructose), insulin
168
What are the key enzymes of fatty acid synthesis?
citrate lyase, acetyl CoA carboxylase, and fatty acid synthase (CRDR)
169
What is the product of the condensation step?
acetoactyl-ACP
170
What is the product of the 1st reduction step?
D-3-hydroxybutyryl-ACP
171
What is the product of the dehydration step?
crotonyl-ACP
172
What is the product of the 2nd reduction step?
butyryl-ACP
