✅ BIOCHEM - Metabolic Pathways Flashcards
(118 cards)
1
Q
Example of an amphibolic pathway
A
Krebs
2
Q
Where does glycolysis occur?
A
Cytoplasm
3
Q
Substrate of glycolysis
A
Glucose
4
Q
End product of glycolysis
A
Pyruvate or lactate
5
Q
Rate limiting step of glycolysis
A
Fructose 6 phosphate -> fructose 1,6 bisphosphate
Enzyme: PFK-1
6
Q
What type of glycolysis happens in cells with mitochondria and adequate O2?
A
Aerobic glycolysis
7
Q
2 stages of glycolysis
A
Energy investment and energy generation
8
Q
3 important steps in glycolysis
A
Step 1
Step 3
Step 10
9
Q
NADH generating step in glycolysis
A
Glyceraldehyde 3 phosphate –> 1,3 bisphosphoglycerate
Enzyme: glyceraldehyde phosphate dehydrogenase
10
Q
Which has a lower km and comsequently higher affinity?
Hexokinase or glucokinase?
A
Hexokinase
11
Q
Glucokinase is present only in what type of tissues
A
Liver
Islet cells of pancreas
12
Q
Hexokinase has a higher Vmax than glucokinase. True or false.
A
False
Glucokinase has a higher Vmax
13
Q
Hexokinase is inhibited by
A
Glucose 6 phosphate
14
Q
Glucokinase is inhibited by
A
Fructose 6 phosphate
15
Q
Glucokinase liver activity is induced by
A
Insulin
16
Q
Action of PFK-2
A
Converts fructose 6 phosphate to fructose 2,6 BP
17
Q
Inhibitor of PFK-1
A
ATP and Citrate
18
Q
Inhibitor of PFK 2
A
Starved state
Decrease insulin and inc glucagon
19
Q
2 steps in glycolysis that produce ATP via substrate level phosphorylation
A
1,3 BPG to 3 PG
Enzyme: phosphoglycerate kinase
PEP to pyruvate
Enzyme: pyruvate kinase
20
Q
2 outcomes of pyruvate in glycolysis
A
Can enter the citric acid cycle in aerobic glycolysis
Can be reduced to lactate in anerobic glycolysis
21
Q
NADH produced in glycolysis cannot pass through thr mitochondrial membrane so it needs what?
A
Malate aspartate shuttle
Glycerol phosphate shuttle
22
Q
Malate aspartate shuttle is used in what organs?
A
Liver kidney heart
23
Q
Glycerol phosphate shuttle is used in which organs?
A
Skeletal muscle
Brain
24
Q
Kinds of metabolic pathways
A
Anabolic
Catabolic
Amphibolic
25
NADH in the malate aspartate shuttle will yield how many ATP?
3
26
NADH in the glycerol phosphate shuttle will yield how many atp?
2
27
In what part of the cell can u find the ETC?
Inner mitochondrial membrane
28
What happens to pyruvate in anaerobic glycolysis?
Lactate dehydrogenase uses up NADH and converts pyruvate to lactate.
29
Anaerobic glycolysis strictly happens in which organs?
```
Cornea
Lens
Kidney medulla
Wbc
Rbc
Testes
```
30
Enzyme responsible for conversion of 1,3 BPG to 2,3 BPG
Bisphosphoglycerate mutase
31
The Luebering-Rapoport pathway bypasses what enzyme
Phosphoglycerate kinase
32
Most common enzyme defect in glycolysis
Pyruvate kinase deficiency
33
Characteristic peripheral smear of G6PD deficiency
Heinz bodies
34
Most common precipitating history of G6PD
Infection
35
Pyruvate is converted to ethanol by
Pyruvate carboxylase (yeasts)
36
Pyruvate is converted to oxaloacetate by
Pyruvate carboxylase (gluconeogenesis)
37
What is the mechanism in arsenic poisoning?
Arsenic inhibits pyruvate dehydrogenase by binding to LIPOIC ACID
38
Pyruvate is converted to acetyl Coa by
Pyruvate dehydrogenase complex
39
Coenzymes of pyruvate dehydrogenase
```
Thiamine pyrophosphate
FAD
NAD+
Coenzyme A (Pantothenic Acid)
Lipoic Acid
```
40
Pyruvate kinase deficiency usually manifests clinically as
Chronic hemolytic anemia
41
Products of conversion of pyruvate to acetyl coa
Acetyl coa
NADH
CO2
42
Most common cause of congenital lactic acidosis
Pyruvate dehydrogenase deficiency
43
Pattern of inheritance of pyruvate kinase deficiency
X-linked DOMINANT
44
Treatment for pyruvate dehydrogenase deficiency
Ketogenic diet
45
Rationale for ketogenic diet in pyruvate dehydrogenase deficiency
Increase lysine and leucine to bypass glycolysis
46
Mechanism of pyruvate dehydrogenase deficiency in chronic alcoholism.
Thiamine deficiency (acquired)
47
Where does the Kreb's cycle occur?
Mitochondrial matrix
48
TCA occurs in the mitochondrial matrix except for which process?
Succinate to fumarate
| Enzyme: succinate dehydrogenase
49
Rate limiting step in krebs
Isocitrate to alpha ketoglutarate
| Enzyme: isocitrate dehydrogenase
50
Inhibitor of aconitase
Fluoroacetate (rat poison)
51
Inhibitor of alpha ketoglutarate dehydrogenase
Arsenite
52
Process in the TCA that produces GTP
Succinyl Coa to succinate
| Enzyme: succinate thiokinase
53
Citrate delivers acetyl Coa to the cytoplasm for ______ via the _______
Fatty acid synthesis via the citrate shuttle
54
Succinyl coa in TCA is also involved in _______
Heme synthesis
| Activation of ketone bodies in extrahepatic tissues
55
Malate in TCA is also use for
Gluconeogenesis
56
What is the main function of gluconeogenesis
Prevent hypoglycemia
57
What is the main function of the Cori cycle?
Conversion of lactate to glucose
58
Gluconeogenesis occurs in which organs
Liver 60% and kidney 10%
Prolonged fasting: kidney up to 40%
59
Gluconeogenesis occur in the
Cytoplasm and mitochondria
60
Rate limiting step in gluconeogenesis
Fructose 1,6 bisphosphate to fructose 6 phosphate
| Enzyme: fructose 1,6 bisphosphatase
61
Energy expense in the cori cycle
4 ATPs
62
In glucogeonesis pyruvate is converted back to PEP through which of the following steps?
Pyruvate to OAA
Enzyme: Pyruvate carboxylase
OAA to PEP
Enzyme: PEP Carboxykinase
63
All carboxylases require _____ as a cofactor
Biotin
64
PEP carboxykinase require ____
GTP
65
Inhibitor of fructose 1,6 BP to fructose 6-P in gluconeogenesis
Fructose 2,6 BP and AMP
66
Energy expenditure in gluconeogenesis
4Atps
2 gtps
2 NADH to NAD+
67
Glucosuria occurs when venous blood glucose concentration exceeds
9.5-10 mmol/L (renal threshold)
| 180 g/dl
68
Redness when drinking is due to which enzyme
Acetaldehyde dehydrogenase
69
High amounts of NADH favors the ff reactions
Pyruvate to lactate
OAA to malate
DHAP to glycerol 3 phosphate
70
Insulin resistance in pregnancy is due to
Human placental lactogen
71
Hyperinsulinemia in pregnancy is due to
Increased estrogen levels
72
Major carbohydrate storage in animals
Glycogen
73
Processes that happen in the cytoplasm and mitochondria
Gluconeogenesis
Urea synthesis
Heme synthesis
74
Glycogen stores are used up after
12-18 hours
75
Glycogen is stored in which 2 organs?
Liver and muscle
76
Activated form of glucose
UDP-glucose
77
Synthesis of new glycogen molecules from alpha-d-glucose
Glycogenesis
78
Rate limiting step in glycogenesis
Elongation of glycogen chains
| Enzyme: glycogen synthase
79
Enzyme involved in conversion of glucose 6 phosphate to glucose 1 phosphate
Phosphoglucomutase
80
Enzyme involved in the synthesis of UDP glucose
UDP glucose phosphorylase
81
Formation of branches in glycogen is mediated by what enzyme
Branching enzyme (amylo and transglucosidase)
82
Glycogen synthase is to glycogenesis
| _____ is to glycogenolysis
Glycogen phosphorylase
83
Glycogen phosphorylase requires what coenzyme
Pyridoxal phosphate
84
Glycogen phosphorylase cannot cleave a 4 glucose residue before a branch called the
Limit dextrin
85
Rate limiting step in glycogenolysis
Removal of glucose using glycogen phosphorylase
86
Lysosomal degradation of glycogen happens with what enzyme
Alpha 1,4 glucosidase
87
Other name of alpha 1,4 glucosidase
Acid maltase
88
In glycogen phosphorylase, the active form is the phosphorylated or dephosphorylated?
Phosphorylated
89
Deficiency in acid maltase
Pompe disease
90
Deficiency in glucose 6 phosphatase
Von gierke disease
91
Deficiency in skeletal muscle glycogen phosphorylase
McArdle's disease
92
Deficient in Andersen's disease
Branching enzyme
93
Cori's disease deficiency
Debranching enzyme
94
Deficient PFK
Tarui's disease
95
Major dietary source of galactose
Lactose
96
Activated form of galactose
UDP galactose
97
Glucose 1 phosphate + UDP glucose forms _____ through which enzyme
UDP galactose and glucose 1 phosphate
Enzyme: galactose 1 P uridyl transferase
98
UDP galactose --> UDP galactose
| Enzyme?
UPD hexose 4 epimerase
99
Main products of the pentose phosphate pathway
NADPH
| Ribose 5 phosphate
100
Substrate of the pentose phosphate pathway
Gucose 6 phosphate
101
The pentose phosphate pathway is divided into the
Oxidative and non oxidative phase
102
Main product of the oxidative phase of the PPP
NADPH
| Ribulose 5 P
103
Phase 1 of PPP is
Oxidative and irreversible
104
Key enzyme in oxidative phase of pentose phosphate pathway
G6PD
105
Key enzymes in non-oxidative phase of the pentose phosphate pathway
Transketolases
106
Transketolases require
Thiamine
107
Rate limiting step in the pentose phosphate pathway
Glucose 6 P to 6 phosphogluconate
| Enzyme: G6PD
108
Reduced glutathione is recreated using
NADPH
| Enzyme: glutathione REDUCTASE
109
Reduced glutathione sequestere harmful H2O2 using
Glutathione peroxidase
110
Drugs that precipitate G6PD deficiency
AAA
Antibiotics (sulfonamides, chloramphenicol)
Antimalarials (primaquine)
Antipyretics (except ASA and Paracetamol)
111
Chronic granulomatous disease is secondary to to deficiency in
NADPH OXIDASE
112
Chronic granulomatous disease is caused by what type of bacteria
Catalase positive
113
Sorbitol dehydrogenase is found in
The seminal vesicles only
Catalyzes sorbitol to fructose (main sperm energy source)
114
Glucose to sorbitol
| What enzyme?
Aldose reductase
115
Mannise is an important component in
Glycoproteins
116
How is mannose 6 P used?
Mannose 6 P is converted to fructose 6 P by
| Phosphomannose isomerase
117
Fructose 1 P to dihydroxyacetone phosphate
| What enzyme?
Aldolase B
118
Fructose to fructose 1 P
Fructokinase or hexokinase
