29 Questions
What is the result of the cross-linking of lens proteins by S-S- bond formation?
Cataracts
What is the result of the accumulation of galactose and galactitol in the eye?
Raised intra-ocular pressure
What is the effect of galactose 1-phosphate accumulation in tissues?
Damage to the liver, kidney, and brain
What is the intermediate of glycolysis that fructose is converted to?
Glyceraldehyde 3-phosphate
What is the enzyme that hydrolyses dietary sucrose?
Sucrase
What is the primary physiological response that triggers gluconeogenesis?
Fasting, starvation, or prolonged exercise
Which enzymes are the major control sites for gluconeogenesis?
PEPCK and Fructose 1,6-bisphosphatase
Which hormone decreases the activity of PEPCK?
Insulin
What is the result of increased rates of gluconeogenesis in the absence of adequate insulin?
Hyperglycemia
Which mechanism does glucagon use to stimulate gluconeogenesis?
Lowering the level of fructose 2,6-bisphosphate
What plays a major role in determining the rate of gluconeogenesis?
Insulin/glucagon ratio
Where does the Citric acid cycle occur?
Mitochondria
What is the end product of the complete oxidation of glucose derivatives?
CO2 and H2O
What is the molecule that most fuel molecules enter the Citric acid cycle as?
Acetyl CoA
How many ATPs are produced during one complete turn of the Citric acid cycle?
12 ATP
What is one of the byproducts of the Citric acid cycle?
All of the above
What happens to one of the three carbons that enter the mitochondria as pyruvate?
It is lost as Co2
What is the primary source of glucose for the central nervous system and other glucose-dependent tissues during fasting and starvation?
Liver glycogen
How long does the glucose stored as liver glycogen last during fasting?
8-10 hours
What is the process by which the body produces glucose from non-carbohydrate precursors during fasting and starvation?
Gluconeogenesis
What is the major site of gluconeogenesis?
Liver
In which organ is galactose primarily metabolized?
liver
What is the purpose of the epimerase reaction during lactation?
to synthesize lactose
What is one of the main substrates of gluconeogenesis?
Lactate
What is formed from the breakdown of proteins in the skeletal muscles during starvation?
Amino acids
What is the result of the reduction of galactose by aldose reductase?
galactitol
What is the consequence of a lack of galactokinase enzyme?
accumulation of galactose in tissues
What is the name of the more severe type of galactosaemia?
Classical type
What is the source of galactose in the diet?
lactose
This quiz covers the effects of galactosemia on body tissues, including the depletion of NADPH and the development of cataracts and glaucoma. Test your knowledge of the biochemical consequences of this genetic disorder.
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