Carbohydrates Flashcards
1
Q
This type of pathway is the link between anabolic and catabolic pathways
A
Amphibolic
2
Q
Krebs cycle is an example of what type of pathway?
A
Amphibolic
3
Q
Protein kinase of cAMP
A
Protein kinase A
4
Q
Protein kinase of IP3/DAG
A
Protein kinase C
5
Q
Sugar units are linked together by what type of bond
A
Glycosidic bond
6
Q
Mirror image of a carbohydrate
A
Enantiomer
7
Q
Hexose monosaccharides
A
Glucose
Fructose
Galactose
Mannose
8
Q
Pentose monosaccharides
A
Ribose
Ribulose
Xylulose
9
Q
Oxidation of glucose yields
A
Glucuronic acid
10
Q
Reduction of glucose yields
A
Sorbitol
11
Q
Monosaccharide that is a constituent of glycoproteins
A
Mannose
12
Q
Monosaccharide that is a structural component of nucleic acids and coenzymes
A
Ribose
13
Q
Monosaccharide that is an intermediate in the pentose phosphate pathway
A
Ribulose
14
Q
Monosaccharide that is excreted in urine in essential pentosuria
A
Xylulose
15
Q
Glucose plus fructose
A
Sucrose
16
Q
Glucose plus galactose
A
Lactose
17
Q
Glucose plus glucose
A
Maltose
18
Q
Most important dietary carbohydrate in cereals, potatoes, legumes with alpha glycosidic bonds
A
Starch
19
Q
Found in plant cell walls
A
Cellulose
20
Q
Polysaccharide of fructose that is readily soluble in water
A
Inulin
21
Q
Insulin stimulated glucose transporter
A
GLUT 4
22
Q
Glucose transporter in brain
A
GLUT 1 and 3
23
Q
Glucose transporter in liver and pancreas
A
GLUT 2
24
Q
Glucose transporter in placenta
A
GLUT 1 and 3
25
Glucose transporter in RBC
GLUT 1
26
Glucose transporter in small intestine
BM- glut 2
| Lumen- glut 5
27
Where does glycolysis occur?
Cytosol
28
Rate limiting step of glycolysis
Fructose 6 phosphate to fructose 1,6 bisphosphate
PFK 1
29
NET ATP in glycolysis
2 ATPs
4 generated
2 consumed- step 1 and 3
30
Enzyme in the 1st step of glycolysis that has low Km and high affinity
Hexokinase
31
Enzyme in the phosphorylation of glucose that is only present in the liver and pancreas
Glucokinase
32
Enzyme inhibited by fructose 6 phosphate
Glucokinase
33
Inhibited by glucose 6 phosphate
Hexokinase
34
Activator of PFK 1
Fructose 2,6 bisphosphate that is a product of PFK 2
35
PFK 2 is activated during the
Well fed state
36
Inhibits PFK 1
Citrate
37
2 steps in glycolysis that produce ATP
1,3 BPG to 3 phosphoglycerate by phosphoglycerate kinase
Phosphoenolpyruvate to pyruvate by pyruvate kinase
38
Step in glycolysis that produces NADH
Glyceraldehyde 3 phosphate to 1,3 BPG by glyceraldehyde 3P dehydrogenase
39
In anaerobic glycolysis, pyruvate is converted to lactate by
Lactate dehydrogenase
40
Which tissues use glycerophosphate shuttle?
Brain
41
Energy yield of glycerophosphate shuttle
1 FADH= 1.5 ATP
42
Which tissues use malate aspartate shuttle
Heart, most tissues
43
Energy yield of malate aspartate shuttle
1 NADH= 2.5 ATP
44
Net ATP yield in aerobic glycolysis
5 or 7
45
Net ATP yield in anaerobic glycolysis
2
46
Found in RBC where step catalyzed by phosphoglycerate kinase is bypassed
2,3 BPG
47
1,3 BPG is converted to 2,3 BPG by this enzyme
Bisphosphoglycerate mutase
48
4 fates of puruvate
Lactate- lactate dehydrogenase
Acetyl CoA- pyruvate dehydrogenase
Ethanol- pyruvate decarboxylase
Oxaloacetate- pyruvate carboxylase
49
Pyruvate is converted to Acetyl CoA through this enzyme
Pyruvate dehydrogenase
50
Coenzymes of pyruvate dehydrogenase
```
Thiamine
FAD
NAD
Coenzyme A
Lipoic acid
```
51
Most common enzyme defect in glycolysis
Pyruvate kinase
52
Pyruvate kinase deficiency can lead to
Hemolytic anemia
53
Deficiency in muscle PFK can lead to
Low exercise capacity
54
Most common cause of congenital lactic acidosis
Pyruvate dehydrogenase deficiency
55
Maturity onset diabetes of the young type 2 is due to mutations that decrease the activity of this enzyme in glycolysis
Glucokinase
56
What element competes with inorganic phosphate as substrate for glyceraldehyde 3P dehydrogenase
Arsenic
57
Chronic alcoholism leads to this vitamin deficiency
Thiamine
58
Final common pathway for the aerobic oxidation of carbohydrates, lipid and proteins
Citric acid cycle
59
Major pathway for formation of ATP
Citric acid cycle
60
Citric acid cycle occurs in what part of the cell
Mitochondria
61
Substrate for glycolysis
Glucose
62
Substrate for citric acid cycle
Acetyl CoA
63
Products of Krebs
2 CO2
1 GTP
3 NADH
1 FADH
64
Rate limiting step of Krebs
Isocitrate to alpha ketoglutarate by isocitrate dehydrogenase
65
Which step in Krebs produces GTP?
Succinyl CoA to succinate step by substrate level phosphorylation
66
Which step in Krebs produces FADH?
Succinate to fumarate step
67
Which step in Krebs produces CO2 and NADH?
Isocitrate to a ketoglutarate
Alpha ketoglutarate to succinyl CoA
Malate to oxaloacetate
68
TCA intermediate that delivers acetyl CoA to the cytosol for FA synthesis
Citrate
69
TCA intermediate used in heme synthesis and ketone body activation
Succinyl CoA
70
TCA intermediate that may be used in gluconeogenesis
Malate
71
True or false:
TCA has hormonal control
False
72
ATP yield for TCA
10 ATP
| 3 NADH, 1 FADH, 1 GTP
73
Complete oxidation of glucose yields how many ATP
30 or 32
74
Pathways occurring in both cytosol and mitochondria
HUG
heme synthesis
Urea cycle
Gluconeogenesis
75
Gluconeogenesis occurs in what organs?
Liver and kidney
76
Gluconeogenesis substrates
Intermediates from glycolysis or TCA
Glycerol and propionyl CoA from TAG
Lactate through Cori cycle
Glucogenic amino acids
77
Rate limiting step of gluconeogenesis
Fructose 1,6 bisphosphate to fructose 6 phosphate through fructose 1,6 bisphosphatase
78
The reaction catalyzed by pyruvate carboxylase in gluconeogenesis requires
Biotin and ATP
79
All carboxylases require this as a cofactor
Biotin
80
Oxaloacetate to phosphoenolpyruvate by PEP carboxykinase requires
GTP
81
Final step in gluconeogenesis that is shared with glycogenolysis
G6P to glucose by glucose 6 phosphatase
82
Pathway where lactate formed by glycolysis in skeletal muscle is transported to liver where it is converted back to glucose through gluconeogenesis
Cori cycle
83
Gluconeogenesis energy requirement
Cleavage of 6 high energy phosphate bonds- 2 GTP and 4 ATP
| 2 NADH
84
Hyperglycemia in critically ill patients can be attributed to
Excessive gluconeogenesis in response to injury and infection
85
Major storage carbohydrate in animals
Glycogen
86
Glycogenolysis occurs in what organs?
Liver and muscle
87
Where does glycogenesis occur?
Cytosol
88
Rate limiting step of glycogenesis
Elongation of glycogen chains through glycogen synthase
89
Protein that serves as a primer for glycogen synthesis when glycogen is completely depleted
Glycogenin
90
Glucose is attached to _________ and becomes the source of all glucosyl residues that are added to the glycogen molecule
Uridine diphosphate
91
Enzymes in synthesis of UDP glucose
Phosphoglucomutase
| UDP glucose pyrophosphorylase
92
A(1-6) bonds are formed by transferring how many glucosyl residues?
5-8
93
Products of glycogenolysis
Glucose in liver
| Glucose 6 phosphate in muscle
94
Rate limiting step of glycogenolysis
Shortening of glycogen chains by glycogen phosphorylase
95
Coenzyme of glycogen phosphorylase
Pyridoxal phosphate
96
Limit dextrin is when there are only how many glucosyl units remaining?
4
97
Debranching enzyme consists of
Alpha 1-4 glucantransferase
| Alpha 1-6 glucosidase
98
Lysosomal degradation of glycogen is through this enzyme
Acid maltase
| Alpha 1-4 glucosidase
99
Von Gierke happens in this enzyme deficiency
Glucose 6 phosphatase
100
Deficiency in lysosomal acid maltase results to
Pompe disease
101
Glycogen storage disease where there is fasting hypoglycemia and muscle weakness due to deficient debranching enzyme
Cori disease
102
Disease where there is increased limit dextrin
Cori cycle
103
Deficient branching enzyme where there is hepatosplenomegaly, increased polysaccharides and heart and liver failure by age 5
Andersen disease
104
McArdle disease where there is poor exercise tolerance is due to deficient
Muscle phosphorylase
105
Hers disease is caused by deficiency in
Liver phosphorylase
106
Galactose to galactose 1P is due to which enzyme
Galactokinase
107
UDP galactose to UDP glucose is mediated by which enzyme
UPD hexose 4 epimerase
108
This enzyme deficiency can cause cataracts in early childhood
Galactokinase
109
This enzyme deficiency can cause vomiting, jaundice, poor growth in children, MR and premature ovarian failure
Galactose 1 phosphate uridyl transferase (GALT) deficiency
110
Fructose 1 P to DHAP
Aldolase B
111
Fructose 1,6 BP to DHAP
Aldolase A
112
Aldolase B defiency can cause these symptoms
Hypoglycemia and vomiting after fructose or sucrose consumption
113
Glucose to sorbitol is catalyzed by
Aldose reductase
114
Sorbitol to fructose is mediated by sorbitol dehydrogenase and is found in these organs
Liver
Ovaries
Seminal vesicles
115
Deficiency in which disaccharide occurs in Inuit people of Greenland and Canada
Sucrase Isolmaltase complex deficiency
116
Alternative pathway for oxidation of glucose in the liver
Uronic acid pathway
117
Main pathway for glucuronic and iduronic acid
Uronic acid pathway
118
Humans cannot synthesize ascorbic acid because of the lack of
L-gulonolactone oxidase
119
Essential component of glycosaminoglycans and detoxification of bilirubin, steroids and morphine
Glucuronic acid
120
Products of pentose phosphate pathway
NADPH
| Ribose 5 phosphate
121
Pathway that neither consumes nor produces ATP
HMP shunt
122
Rate limiting step of pentose phosphate pathway
Glucose 6P to 6 phosphogluconate
Glucose 6P dehydrogenase
123
G6P dehydrogenase is the key enzyme in which phase of the HMP shunt?
1st phase
124
What phase of the PPP is oxidative and irreversible?
1st phase
125
What is the product of the 1st phase of PPP
2 NADPH
126
What is the enzyme of the 2nd phase of the HMP shunt?
Transketolases
127
Cofactor of transketolases in the pentose phosphate pathway
Thiamine
128
Product of the 2nd phase of PPP
Ribose 5 phosphate
129
This substance removes H2O2 in a reaction catalyzed by glutathione peroxidase
Glutathione
130
Most common disease producing enzyme abnormality
G6PD deficiency
131
Pathology in G6PD where there is altered hemoglobin that precipitates in the RBC
Heinz bodies
132
Abnormally shaped RBCs in G6PD due to phagocytic removal of Heinz bodies in spleen
Bite cells
133
Disease that is due to NAPH oxidase deficiency that converts molecular oxygen into superoxidase and used in respiratory burst that kills bacteria
Chronic Granulomatous Disease
