Carbohydrates Flashcards
(216 cards)
1
Q
Give 4 monosaccharide hexoses
A
Glucose
Fructose
Galactose
Mannise
2
Q
Reduction of glucose yields______
A
Sorbitol
3
Q
Oxidation of glucose yields______
A
Glucuronic acid
4
Q
Hexose obtained from mammary glands
A
Galactose
5
Q
Hexose that is constituent of glycolipids and glycoproteins
A
Galactose
6
Q
Give 3 pentose
A
Ribose
Ribulose
Xylulose
7
Q
Hexose intermediate in pentose phosphate pathways
A
Ribulose
8
Q
Pentose excreted in urine in essential pentosuria
A
Xylulose
9
Q
Non-reducing disaccharide
A
Sucrose
10
Q
Give 2 reducing disaccharides
A
Lactose
Maltose
11
Q
Intermediate disaccharide in the digestion of starch
A
Maltose
12
Q
Storage polysaccharide in animals
A
Glycogen
13
Q
Chief constituent polysaccharide of plant cell wall
A
Cellulose
14
Q
Polysaccharide of fructose that is readily soluble in water and is used to determine GFR
A
Inulin
15
Q
Example of ketose
A
Fructose
16
Q
Examples of aldose
A
Glucose
Galactose
Mannose
17
Q
Isomers/Epimers/Enantiomers/Anomers
Compounds that have the same chemical formula
A
Isomers
18
Q
Isomers/Epimers/Enantiomers/Anomers Glucose Fructose Galactose Mannose
A
Isomers
19
Q
Isomers/Epimers/Enantiomers/Anomers
Isomers that differ in configuration around only one specific carbon atom (except the carbonyl carbon)
A
Epimers
20
Q
Isomers/Epimers/Enantiomers/Anomers
Glucose and galactose
A
Epimers
Differ only at OH position in C4
21
Q
Isomers/Epimers/Enantiomers/Anomers
Glucose and mannose
A
Epimers
Differ only at OH at C2
22
Q
Isomers/Epimers/Enantiomers/Anomers
Are optical isomers or stereoisomers
A
Enantiomers
23
Q
Isomers/Epimers/Enantiomers/Anomers
Pairs of structures that are mirror images of each other
A
Enantiomers
24
Q
Isomers/Epimers/Enantiomers/Anomers
D sugar and L sugar
A
Enantiomers
25
Monosaccharide stucture with a five membered ring
Furanose
26
Monosaccharide structure with six-membered ring
Pyranose
27
Isomers/Epimers/Enantiomers/Anomers
| Rotation around the carbonyl carbon produces _____ which are labeled alpha and beta
Anomers
28
Unlike epimers, anomers can undergo interconversion (from alpha to beta, and vice versa) without energy expenditure or need for enzymes, in a process called _____
Mutarotation
29
2 body tissues that require insulin for glucose cellular transport
Adipose
| Muscle
30
Glucose transporter
RBC
Brain, kindey colon, placenta
Glut 1
31
Glucose transporter
Liver, pancreas
Small intestine, kidney
GLUT 2
32
Glucose transporter
Brain
Kidney, Placenta
GLUT 3
33
Glucose transporter
Muscle
Adipose
Heart, skeletal muscle
GLUT 4
34
Glucose transporter
| Small intestine
GLUT 5
35
Glucose transporter
| Small intestine, kidney
SGLT 1
36
Glucose transporter
| Insulin-stimulated glucose uptake
GLUT 4
37
Glucose transporter
| Frucose absorption
Small intestine
38
Glucose transporter
| Sodium-dependent active uptake of glucose against a concentration gradient
SGLT 1
39
Major pathway for glucose metabolism that converts glucose into 3 carbon compounds to provide energy
Glycolysis
40
Most common type og glycolysis
Embden-Maeyerhoff-Parnas Pathway
41
Site of glycolysis
Cytosol
42
Substrate for glycolysis
Glucose
43
What are the end-products of glycolysis
2 molecules of either pyruvate or lactate
44
Rate-limiting step in glycolysis
F6P—>F1,6BP
| Enzyme: PFK 1
45
Rate-limiting enzyme in glycolysis
PFK1
46
Identify enzyme
| Glucose—>G6P
Hexokinase
47
Hexokinase/Glucokinase
| Present in most tissues
Hexokinase
48
Hexokinase/Glucokinase
| Can phosphorylase glucose and other hexoses
Both
49
Hexokinase/Glucokinase
| Present only liver parenchyma and islet cells of pancreas
Glukokinase
50
Hexokinase/Glucokinase
| Inhibited by G6P
Hexokinase
51
Hexokinase/Glucokinase
| Inhibited by F6P
Glucokinase
52
Hexokinase/Glucokinase
| Low Km, high affinity
Hexokinase
53
Hexokinase/Glucokinase
| High Km, low affinity
Glucokinase
54
Hexokinase/Glucokinase
| Low Vmax
Hexokinase
55
Hexokinase/Glucokinase
| High Vmax
Glucokinase
56
Hexokinase/Glucokinase
| Liver activity induced by iinsulin
Glucokinase
57
Identify enzyme
| G6PF6P
Phosphohexose isomerase
58
Identify enzyme
| F6P—>F1,6BP
PFK1
| Rate-limiting enzyme of glycolysis
59
PFK1/PFK2
| Product is F1,6BP
PFK1
60
PFK1/PFK2
| Product is F2,6BP
PFK2
61
PFK1/PFK2
| Activated by F2,6BP and AMP
PFK1
62
2 activators of PFK1
F2,6BP
| AMP
63
PFK1/PFK2
Activated by well-fed state
Increased insulin
Decreased glucagon
PFK2
64
PFK1/PFK2
| Inhibited by citrate and ATP
PFK1
65
PFK1/PFK2
Inhibited during fasting state
Decreased Insulin
Increased glucagon
PFK2
66
2 inhibitors of PFK1
Citrate
| ATP
67
Inhibitors of PFK2
Fasting state
Dec insulin
Inc glucagon
68
Identify enzyme
| F1,6BP—>DHAP and GA3P
Aldolase
69
Identify enzyme
| DHAP—>GA3P
Triose phosphate isomeras
70
Identify enzyme
| GA3P—>1,3BPG
Glyceraldehyde phosphate dehydrogenase
71
Identify enzyme
| 1,3BPG—> 3PG
Phosphoglycerate kinase
72
Identify enzyme
| 3PG—>2PG
Phosphoglycerate mutase
73
Identify enzyme
| 2PG—> PEP
Enolase
74
Identify enzyme
| PEP—>Pyruvate
Pyruvate kinase
75
How many ATP per molecule of PEP is produced in substrate-level phosphorylation
1
76
What activates pyruvate formation
F1,6BP
77
Hormone that inhibits pyruvate formation
Glucagon
78
2 steps in glycolysis that produce ATP
1,3BPG—>3PG (enzyme: phosphoglycerate kinase)
| PEP—>Pyruvate (enzyme: pyruvate kinase)
79
2 enzymes in involved in ATP-producing steps in glycolysis
Phosphoglycerate kinase
| Pyruvate kinase
80
Step in glycolysis that produces NADH
GA3P—> 1,3BPG
| enzyme: glyceraldehyde 3 phosphate dehydrogenase
81
Enzyme involved in NADH-producing step in Glycolysis
Glyceraldehyde 3 phosphate dehydrigenase
82
End product of aerobic glycolysis
Pyruvate
83
End product of anaerobic glycolysis
Lactate
84
Identify enzyme
| Pyruvate—>lactate
Lactate DH
| NADH used
85
Major fate of pyruvate in lens, cornea, kidney medulla, testes, RBC, WBC
Lactate
86
Glycerophosphate shuttle/Malate aspartate shuttle
| ATP yield per NADH is 1.5
Glycerophosphate
87
Glycerophosphate shuttle/Malate aspartate shuttle
| ATP yield per NADH is 2.5
Malate aspartate
88
Glycerophosphate shuttle/Malate aspartate shuttle
| Tissues: Brain, white muscle
Glycerophosphate
89
Glycerophosphate shuttle/Malate aspartate shuttle
| Tissue: heart and most tissues
Malate aspartate
90
Net ATP yield for aerobic glycolysis glycerophosphate shuttle
5
| See page 9 of topnotch handout
91
Net ATP yield for aerobic glycolysis malate aspartate shuttle
7
92
Net ATP yield for anaerobic glycolysis
2
93
Fate of pyruvate and enzyme involved
| Anaerobic glycolysis
Lactate, lactate DH
94
Fate of pyruvate and enzyme involved
| Fermentation
Ethanol
| Pyruvate decarboxylase
95
Fate of pyruvate and enzyme involved
| Gluconeogenesis
OAA, pyruvate carboxylase
96
Fate of pyruvate and enzyme involved
| Citric acid cycle
Acetyl CoA, pyruvate DH
97
Identify enzyme
| Pyruvate—> Acetyl Coa
Pyruvate DH complex (E1 + E2 + E3)
98
Enumerate coenzymes of pyruvate DH complex
```
Thiamine pyrophosphate
FAD
NAD+
Coenzyme A (contains panthotenic acid)
Lipoic acid
```
99
Most common enzyme defect in glycolysis and its presentation
Pyruvate dehydrogenase, hemolytic anemia
100
Identify enzyme
Provide lipids as alternative fuel
Deficiency presents as low exercise capacity, especially on high carbohydrate diets
Muscle phosphofructokinase
101
Identify enzyme
| Its deficiency is the most common cause of congenital lactic acidosis
Pyruvate dehydrogenase
102
Clinical manifestation af ALDOLASE A deficiency
Hemolytics anemia
103
Treatment for pyruvate dehydrogenase deficiency
Ketogenic diet
104
In arsenic poisoning, arsenic competes with inorganic phosphate as a substrate of what glycolytic enzyme
Glyceraldehyde 3 phosphate dehydrogenase
105
Deficiency of this glycolytic enzyme leads to acumulation of lactate, decreased acetyl CoA, leading to psychomotor retardation and death
Pyruvate dehydrogenase
106
Final common pathway for the aerobic oxidationof carbohydrates, lipids and proteins
Citric acid cycle
107
Site of TCA
Mitochondria
108
All substrates of TCA are in mitochondrial matrix except
Succinate dehydrogenase (inner mitochondrial membrane)
109
Initial substrate for TCA
Acetyl CoA
110
Products of TCA
2 CO2
1 GTP
3 NADH
1 FADH2
111
Rate-limiting step in TCA
Isocitrate—>alpha kg
| Enzyme: isocitrate dehydrogenase
112
Enzyme for rate-limiting step of TCA
Isocitrate dehydrogenase
113
Identify enzyme
| Acetyl CoA + OAA —> Citrate
Citrate synthase
114
In TCA, Acetyl CoA + ______ —> citrate
OAA
115
Identify enzyme and inhibitor
| Citrate —-> isocitrate
Aconitase,
| Fluoroacetate
116
Identify enzyme and byproduct
| Isocitrate—> alpha kg
Isocitrate dehydrogenase,
| CO2, NADH
117
Identify enzyme, by-products and inhibitor
| Alpha kg —> succinyl CoA
Alpha kg dehydrogenase
CO2, NADH
Arsenite and ammonia
118
Identify enzyme and by-product
| Succinyl CoA—>Succinate
Succinate thiokinase,
| GTP
119
Identify enzyme and by-product
| Succinate—>Fumarate
Succinate dehydrogenase
| FADH2
120
Identify enzyme
| Fumarate—>malate
Fumarase hydratase
121
Identify enzyme and by-product
| Malate—>OAA
Malate dehydrogenase
| NADH
122
3 reactions in TCA that produce NADH as by-product
Isocitrate—>alpha kg
Alpha kg—>succinyl CoA
Malate—> OAA
123
Reaction in TCA that produces GTP
Succinyl CoA—>Succinate
124
Reaction in TCA that produces FADH2
Succinate —> fumarate
125
TCA intermediate that delivers acetyl CoA to the cytosol dor fatty acid synthesis via its shuttle
Citrate
126
TCA intermediate used for heme synthesis and activation of ketone bodies in extrahepatic tissues
Succinyl CoA
127
TCA intermediate used for gluconeogenesis
Malate
128
T/F TCA does not synthesize new OAA
T
129
T/F
| TCA proceeds under hormonal control
F
130
T/F
| Four B vitamins are essential for TCA
T
131
These are reactions that replenish intermediates of the TCA that have been used for biosynthesis
Anaplerotic reactions
132
Most important anaplerotic reaction that maintains adequate comcentration of OAA
```
Pyruvate carboxylase
Other anaplerotic susbtrates:
Glutamine
Glutamate
Aspartate
Propionyl CoA
```
133
Total ATP yield for 1 cycle of TCA
10
NADH (2.5x3)
FADH2 (1.5x1)
GTP (1)
134
Total ATP yieald for complete oxidation of glucose
30 or 32
Glcose —> Pyruvate 5 or 7
2 pyruvate —> Acetyl CoA 2.5 from NADH x 2 = 5
2 acetyle CoA in TCA —> 10 x 2 = 20
135
Process of synthesizing glucose from non-carbohydrate sources
Gluconeogenesis
136
Organ site of gluconeogenesis
Liver 90%
| Kidney 10%
137
Site of gluconeogenesis in the cell
Mitochondria and cyosol
138
```
Substrates of gluconeogenesis include:
Intermediates of glycolysis and TCA
_____ through the Cori cycle
_____ and ______ from TAG
Carbon skeletons of glucogenic AA
```
Lactate
| Glycerol, propionyl CoA
139
Rate-limiting step in gluconeogenesis
F1,6BP—>Fructose 6 Phosphate
| Enzyme: fructose 1,6 bisphophatase
140
Gluconeogenesis
Identify enzyme
Pyruvate—>OAA
Pyruvate carboxylase
141
2 Co-factors of pyruvate carboxylase in gluconeogenesis
ATP
Biotin (CARBOXYLASES attach carbon atom with CO2 as a substrate. All carboxylases require biotin as co-factor)
Pyruvate —> OAA (pyruvate carboxylase)
Acetyl CoA—> malonyl CoA (Acetyl CoA carboxylase)
Propionyl CoA —> methylmalonyl CoA ( propionyl CoA carboxylase)
142
Gluneogenesis
| Pyruvate carboxylase is allosterically activated by______
Acetyl CoA
143
In gluconeogenesis, OAA is reduced to _______ and exported from the mitochondrion tonthe cytosol, where it is converted back to OAA
Malate
144
Identify the enzyme in gluconeogenesis
| OAA—> PEP
PEP Carboxykinase
145
Key enzyme that catalyzes net transfer out of the citric acid cycle into gluconeogenesis
PEP carboxykinase
| OAA—>PEP
146
Rate-limiting enzyme of gluconeogenesis
Fructose 1,6 bisphosphatase
| Inhibited by fructose 2,6 bisphosphate and AMP
147
What inhibits the rate-limiting enzyme of gluconeogenesis?
Fructose 2,6 bisphosphate
| AMP
148
Final step shared by gluconeogenesis and glycogenolysis
Glucose-6-phosphate—>Glucose
| Enzyme: glucose-6-phosphatase
149
The cycle through which lactate formed by glycolysis in skeletal muscle is transported to the liver where it is converted back to glucose through gluconeogenesis
Cori cycle
150
Gluconeogenesis from pyruvate requires
Cleavage of ______ bonds
Oxidation of ______
Gluconeogenesis from pyruvate requires
Cleavage of 6 high-enerfy phosphate bomds (4 ATP + 2 GTP)
Oxidation of 2 NADH
151
Energy for gluconeogenesis comes from _____
Oxidation of fatty acids
152
Glucosuria occurs when venous blood glucose concentration exceeds _____mmol/L (renal threshold)
10
153
Major storage of carbohydrate in animals
Glycogen
154
Approximately ____g of glycogen is stored in the liver
500
155
Glygogen is a branched polymer of alpha D glucose
With primary glycosidic bond at ______
And branch pointd after 8 to 10 residues at _____
a (1->4)
| a (1->6)
156
Site of glycogenesis
Cytosol
| Liver and muscle
157
Substrate for glycogenesis
a-D-glucose
158
Rate-limiting step for glycogenesis
Elongation of glycogen chains
| ie, creation of a(1,4) glycosidic bonds by enzyme glycogen synthase
159
Each glycogen chain how how many glucose residues?
12-14
160
Protein that serves as primer for glycogen synthesis when glycogen is completely depleted
Glycogenin
161
Identify the 2 enzymes
G6P—>G1P
G1P + UTP —> UDP-Glucose
Phosphoglucomutase
| UDP-glucose pyrophosphorylase
162
In glycogenesis, the rate limiting enzyme _____ forms _____ bonds between glucise residues. Hence, elongation of the chain
Glycogen synthase
| a(1->4)
163
In glycogenesis, branch formation is facilitated by ____ enzyme, which forms a(1->6) bonds by transferring 5 to 8 glucosyl residues
```
Branching enzyme composed of
amylo a(1->4) to a(1->6) transglucosidase
```
164
Alpha (1->4) glycogen bonds form at the (reducing/non-reducing end)
Non-reducing
| ie, carbon 4
165
Site of glycogenolysis
Liver and muscle
| Cytosol
166
Products of glycogenolysis
Glucose in liver
| Glucose-6-phosphate in muscle
167
Rate-limiting step for glycogenolysis
Shortening of glycogen chains
| Enzyme: glycogen phosphorylase
168
In glycogenolysis, shortening of chains proceeds with sequential cleavage of ____ bonds between glucosyl residues at the non-reducing end of the molecule
a(1->4)
169
Rate-limiting enzyme in glyconolysis and its coenzyme
Glycogen phosphorylase
| Pyridoxal phosphate
170
In glycogenolysis, shortening of chains stops when
When only 4 glucosyl units remain
| Limit dextran
171
Removal of branches in glycogenolysis is facilitated by what enzyme
Debranching enzyme composed of
a(1->4) glucantransferase
Amylo a(1->6) glucosidase
172
In glycogenolysis, cleavage of what bonds yield free glucose
a(1->6)
173
Enzyme for lysosomal degradation of glycogen and disease associated
Alpha (1->4) glucosidase aka acid maltase
| Deficient in Pompe disease
174
A. Glycogen synthase/B. Glycogen phosphorylase
| Activated by Glucose-6-phosphate
A
175
A. Glycogen synthase/B. Glycogen phosphorylase
| Inhibited by ATP
B
176
A. Glycogen synthase/B. Glycogen phosphorylase
| Activated by calcium (muscle)
B
177
A. Glycogen synthase/B. Glycogen phosphorylase
| Activated by glucagon and epinephrine
B
178
A. Glycogen synthase/B. Glycogen phosphorylase
| Inhibited by glucagon and epinephrine
A
179
A. Glycogen synthase/B. Glycogen phosphorylase
| Activated by insulin
A
180
A. Glycogen synthase/B. Glycogen phosphorylase
| Inhibited by insulin
B
181
A. Glycogen synthase/B. Glycogen phosphorylase
| Active when phosphorylated
B
182
A. Glycogen synthase/B. Glycogen phosphorylase
| Active when dephosphorylated
A
183
Phosphorylation of galactose into galactose 1 phosphate is facilitated by
Galactokinas
184
Formation of UDP galactose is facilitaed by what enzyme
Galactose 1 P uridyl transferase (GALT)
185
Identify enzyme that facilitates use of galactose as carbon source
UDP hexose 4 epimerase
| Reaction: UDP galactose —> UDP glucose
186
Identify enzyme deficiency
Cataracts in early childhood
Galactosemia, galactosuria
Autosomal recessive
Galactokinase deficiency
187
Identify enzyme deficiency
Severe symptoms of galactosemia, galactosuria, cataracts, diarrhea, vomiting, jaundice
Poor growth in children, severe mental retardarion, liver damage
Premature ovarian failure in children
Galactose 1 phosphate uridyl transferase deficiency
188
Enxyme for phosphorylation of fructose
Fructokinase or hexokinase
189
Identify enzyme
| Fructose 1 P —> DHAP + glyceraldehyde
Aldolase B
190
Clinical manifestation of essential fructosuria (fructokinase deficiency)
Asymtomatic
191
Identify enzyme deficiency
Profound hypoglycemia and vomiting
Jaundice, hemorrhage, hepatomegaly, renal dysfunction, hyperuricemia, lactic acidosis, death
Symptoms appear after waening from milk
Aldolase B deficiency
| Hereditary fructose intolerance
192
What pathway
| Glucose—> Sorbitol —> Fructose
Polyol pathway
193
In polyol pathway, what enzyme catalyzes this rxn
| Glucose—> Sorbitol
Aldolase reductase
194
Aldolase reductase used in polyol pathway is found in what tissues
```
Lens
Retina
Schwann cells
Liver
Kidney
Placenta
RBC
Ovaries
Seminal vesicles
```
195
Identify enzyme
| Sorbitol—>fructose
Sorbitol dehydrogenase
196
Give 3 tissues that contain enzyme sorbitol dehydrogenase
Liver
Ovaries
Seminal vesicles
197
T/F
| Uronic acid pathway does not produce glucose
T
198
Alternative pathway for oxidation of glucose
| And ascorbic acid in plants and animals
Uronic acid pathway
199
Absence of this enzyme in guinea pigs and primates renders them incapable of synthesis of ascorbic acid
L gulonolactone oxidase
200
Essential component of GAGs
Required in detox of insoluble compounds such as
Bilirubin, steroids, morphine and other drugs
Glucuronic acid
201
Clinical manifestation of essential pentosuria
Increased xylulose in the urine
| Xylulose reductase deficiency
202
T/F Pentose phosphate pathway produces 10 ATP and consumes 2 ATP overall
F
| PPP does not produce nor consume ATP
203
2 products of PPP
NADPH
| Ribose 5 phosphate for synthesis of nucleotides
204
Where does PPP occur?
Cytosol
RBC
Tissues that produce lipids ( liver, adipose, adrenals, thyroid, testes, lactating mamaries
205
Substrate for PPP
Glucose-6-phosphate
206
Rate-limiting step for PPP and enzyme
Glucose 6 P—> 6 phosphogluconate
| Enzyme: Glucose 6 phosphate dehydrogenase
207
2 phase of PPP
Oxidative (irreversible)
| Non-oxidative (reversible)
208
Key enzyme and products of oxidative phase if PPP
G6P dehydrogenase
2 NADPH
Ribulose 5 phosphate
209
Key enzyme and products of non-oxidative phase of PPP
Transketolases( cofactors: thiamine
Transaldolases
Ribose 5 P
F6P
Glyceraldehyde 3 phosphate
210
Substrate for reductive biosynthesis of fatty acid synthesis and steroids
Glutathione reduction inside RBCs
NADPH
211
Most common disease producing enzyme in humans
G6PD
212
Precipitating factors for G6PD
Infection (most common)
Drugs (sulfonamides, primaquine, chloramphenicol)
Fava beans
213
Altered hemoglobin that precipitates within RBCs
Heinz bodies
214
Abnormally shaped RBCs due to phagocytic removal of Heinz bodies in spleen
Bite cells
215
Chronic granulomatous disease is caused by deficiency of what enzyme
NADPH oxidase
216
Enzyme that converts molecular oxygen into superoxide in leukocytes (especially netrophils and macrophages) used in the respiratory burst that kills bacteria
NDPH oxidase
