Random (Metabolism) Flashcards
Inhibitors of glycolysis
- Arsenate and iodoacetate - glyceraldehyde 3 phosphate dehydrogenase
- Flouride - enolase
Allosteric regulation of glycolysis
Phosphofructokinase Activators: Fructose 2,6 bisphosphate, ADP, AMP Inhibitors: ATP, citrate, acidic pH
PDH complex is dependent on
TPP Lipoamide Coenzyme A FAD NAD+
Main precursors of gluconeogenesis
Pyruvate Lactate Glucogenic AA Glycerol Propionate
Regulatory enzymes of gluconeogenesis
Pyruvate carboxylase
PEP-CK
Fructose 1,6 bisphosphatase
Glucose 6 phosphatase
Type 0 glycogen storage disease
- liver glycogen synthase deficiency
- low glycogen stores
Type 1 GSD
- Von Gierkes
- glucose 6 phosphotase deficiency
- accumulation of glycogen
- fasting hypoglycemia
- enlargement of liver
- lactic acidosis
Type 2 GSD
- Pompes
- lysosomal ā(1,4) ā(1,6) glucosidase
- glycogen accumulates in lysosomes
- heart failure
Type 3 GSD
- Coris
- debranching enzyme ā(1,6) glucosidase
- hepatomegaly
- symptoms vanish at puberty
- similar to von Gierkes
Type 4 GSD
- Anderson’s
- branching enzyme amylo(1,4-1,6) transglycolase
- most severe
- long unbranched chains accumulate and are recognized as foreign bodies
- cardiac and liver failure before age 5
Type 5 GSD
- McArdles
- muscle glycogen phosphorylase
- sufficient glycogen stores but cannot be released
- can’t tolerate strenuous activity
Type 6 GSD
- Hers
- liver glycogen phosphorylase
- impaired hepatic glycogenolysis
- hepatomegaly
Type 7 GSD
- Taruis
- phosphofructokinase in muscle and RBC
- hemolytic anemia
- exercise intolerance
Chief regulatory enzyme of HMP shunt
Glucose 6 phosphate dehydrogenase
G6PD inhibited by
NADPH
Essential fructosuria
Fructokinase
Accumulation of fructose and its excretion in urine
Hereditary fructose intolerance
Aldolase B
Accumulation of fructose 1 phosphate
High intake of fructose rich food
Excess formation of fatty acids Increased TAG and LDL Decreased intracellular organic phosphate Decreased synthesis of ATP Increased synthesis of purines Gout
Why retinopathy in diabetes?
Accumulated glucose is converted to sorbitol with aldose reductase.
But sorbitol dehydrogenase is only present in seminal vesicles and ovaries.
So sorbitol accumulates in retina and tissues causing retinopathy
Galactosemia
Galactose 1 P uridyl transferase Excess galactose in blood Excess is converted to galactitol MR, jaundice, hepatomegaly, proteinuria CONGENITAL CATARACT
Gestational diabetes mellitus
When carbohydrate intolerance is noticed for the first time during pregnancy
- can cause neonatal mortality
- fetus secrets more insulin leading to increased birth weight of fetus
Type 1 DM
- Decreased insulin production
- early onset
- T cells attack insulin secreting cells of islets of langerhans
Type 2 DM
- decreased response to insulin
- late onset
Metabolic syndrome
Abdominal obesity + hypertryglyceridemia + high BP + high plasma glucose
- Insulin resistance syndrome
- increased risk of CAD and type 2 DM
Kimmelstiel Wilson syndrome
- Complication of DM
- Nephrosclerosis
- proteinuria
- renal failure
Mucopolysaccharidoses
Intralysosomal accumulation of GAG in tissues
- coarse facial features
- thick skin
- corneal opacity
- MR
Tay Sachs disease
- Failure of degradation of gangliosides
- Low Hexosaminidase A
- cherry red spot in macula
Hyperammonemia
- feature of liver failure
- also called portal systemic encephalopathy
- toxins produced in intestines bypass liver
- conc. in blood increases
- CNS dysfunction
- jaundice, hepatomegaly
Lactose intolerance
- deficiency of lactase
- lactose accumulates in gut
- diarrhea and flatulence
- secondary - lactase activity decreases as age advances
- treated with curd or yeast as they are rich in lactase
Glucose galactose malabsorption
- Defective SGluT-1
- transporter of glucose in intestine
- secondary active transport
Congenital renal glycosuria
- defective SGluT-2
- transporter of glucose in kidneys
- secondary active transport
Oral rehydration solution
- treatment for diarrhea
- contains glucose and sodium
- allows absorption of Na to replenish NaCl levels and glucose to provide energy
Pasteur effect
The inhibitory effect of oxygen on glycolysis
Warburg hypothesis
- cancer cells utilise energy from glycolysis
- they require lesser oxygen
- inhibition of glycolysis depletes ATP in cancer cells leading to cell death.
- warburg effect and hypoxia are frequently seen in human cancers
Deficiency of glycolytic enzymes
- mainly pyruvate kinase and hexokinase
- hemolytic anaemia
- hexokinase deficient RBC have low 2,3 BPG and high O2 affinity
- PK deficient RBC have high 2,3 BPG and low O2 affinity
Malignant hyperthermia
- occurs when halothane is given as anaesthetic
- calcium release channel is defective
- inappropriate release of Ca from sarcoplasmic reticulum
- uncontrolled heat generation
- ATP depletion
- Lactic acidosis
- CPK elevated
Essential pentosuria
-one of members of Garrods triad
-decreased xylitol dehydrogenase and xylitol reductase
-L glucose is not converted to D glucose and is excreted in urine
-benedicts test +ve
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