Important terms and exam questions to study for Medical Biochemistry, Vrije
Universiteit Amsterdam (AB_1198)
Study these well, and you will be guaranteed of a good grade on your exam!
Amino acids ---> Which of the following three molecules cannot be stored for
energy?
Glucose, amino acids, fats
Acetyl-CoA ---> In the TCA cycle, two carbons in the form of _________ are
added to oxaloacetate at the start of the cycle.
CO2; H2O ---> In the TCA cycle, two carbons of Acetyl-coA are released as
______ and hydrogens are released as ______ .
In the cytoplasm. ---> Where does glycolysis occur?
fatty acids. ---> When there's sufficient ATP, excess Acetyl-coA is converted to:
fatty acids. ---> An excess of glucose is converted into:
acetoacetate and beta-hydroxybutyrate ---> What are the names of the two main
ketone bodies?
Glucose stimulates hexokinase to convert it into glucose-6-phosphate.
Glucose-6-phosphate then inhibits hexokinase. ---> How is hexokinase allostericly
regulated?
Liver and pancreas, inside the nucleus. ---> Where is glucokinase found?
Most tissues (excludes liver and pancreas beta cells) in the cytoplasm. ---> Where
is hexokinase found?
This mechanism allows glycogen phosphorylase activity to be regulated by the level
of glucose so that glycogen is not broken down when glucose is already plentiful.
---> Glucose binds to glycogen phosphorylase and competitively inhibits the
enzyme. What is the physiological advantage of this?
Hexokinase. ---> What glycolytic enzyme has a high Vmax, high Km, and low
affinity for glucose?
, Glucokinase = In the liver, high affinity for glucose.
Hexokinase = Non-liver cells, low affinity for glucose. ---> What is the main
difference between glucokinase and hexokinase?
When blood glucose are high. It is released after a carbohydrate rich meal. --->
When does the body release insulin?
When glucose levels are low (ezelsbruggetje: glucaGON(E)). ---> When does the
body release glucagon?
Insulin stimulates the production (i.e. the amount of enzymes) of hexokinase and
glucokinase. ---> Which two enzymes does insulin stimulate?
Converts glucose to glucose-6-phosphate by using ATP. ---> What does
glucokinase do?
Converts glucose into glucose-6-phosphate by using ATP. ---> What does
hexokinase do?
3.5 - 5.6 mmol/l ---> In a healthy person the blood glucose level under fastening
conditions is:
Plasma contains fibrinogen (blood clotting agent) and red blood cells; serum does
not. The serum is obtained after blood clotting, while plasma can be obtained before
the coagulation of the blood. ---> What is the difference between serum and
plasma? How are both obtained?
When on a carb-free diet, glucose is not readily available and needs to be made by
gluconeogenesis in the liver. Amino acids are used in the liver for this process. They
are first converted into Acetyl-CoA and can then go through gluconeogenesis. --->
Current recommendations advise to use extra protein or amino acid supplements
when on a carb-free diet. Why is this essential, and for which process in the liver are
they used?
- Insulin stimulates the uptake of glucose (GLUT4 receptors), as well as glycolysis
and lipolysis and glycogen synthesis. Insulin inhibits glycogenolysis.
- Glucagon activates gluconeogenesis and glycogenolysis, as well as lipogenesis.
Glucagon inhibits glycolysis by inhibiting hexokinase and glucokinase. ---> What
are the effects of insulin and glucagon on fat cells and on muscle cells?
When Acetyl-CoA is in high concentration pyruvate carboxylase is activated. This
signifies that products have been converted into acetyl coa and can be further
Universiteit Amsterdam (AB_1198)
Study these well, and you will be guaranteed of a good grade on your exam!
Amino acids ---> Which of the following three molecules cannot be stored for
energy?
Glucose, amino acids, fats
Acetyl-CoA ---> In the TCA cycle, two carbons in the form of _________ are
added to oxaloacetate at the start of the cycle.
CO2; H2O ---> In the TCA cycle, two carbons of Acetyl-coA are released as
______ and hydrogens are released as ______ .
In the cytoplasm. ---> Where does glycolysis occur?
fatty acids. ---> When there's sufficient ATP, excess Acetyl-coA is converted to:
fatty acids. ---> An excess of glucose is converted into:
acetoacetate and beta-hydroxybutyrate ---> What are the names of the two main
ketone bodies?
Glucose stimulates hexokinase to convert it into glucose-6-phosphate.
Glucose-6-phosphate then inhibits hexokinase. ---> How is hexokinase allostericly
regulated?
Liver and pancreas, inside the nucleus. ---> Where is glucokinase found?
Most tissues (excludes liver and pancreas beta cells) in the cytoplasm. ---> Where
is hexokinase found?
This mechanism allows glycogen phosphorylase activity to be regulated by the level
of glucose so that glycogen is not broken down when glucose is already plentiful.
---> Glucose binds to glycogen phosphorylase and competitively inhibits the
enzyme. What is the physiological advantage of this?
Hexokinase. ---> What glycolytic enzyme has a high Vmax, high Km, and low
affinity for glucose?
, Glucokinase = In the liver, high affinity for glucose.
Hexokinase = Non-liver cells, low affinity for glucose. ---> What is the main
difference between glucokinase and hexokinase?
When blood glucose are high. It is released after a carbohydrate rich meal. --->
When does the body release insulin?
When glucose levels are low (ezelsbruggetje: glucaGON(E)). ---> When does the
body release glucagon?
Insulin stimulates the production (i.e. the amount of enzymes) of hexokinase and
glucokinase. ---> Which two enzymes does insulin stimulate?
Converts glucose to glucose-6-phosphate by using ATP. ---> What does
glucokinase do?
Converts glucose into glucose-6-phosphate by using ATP. ---> What does
hexokinase do?
3.5 - 5.6 mmol/l ---> In a healthy person the blood glucose level under fastening
conditions is:
Plasma contains fibrinogen (blood clotting agent) and red blood cells; serum does
not. The serum is obtained after blood clotting, while plasma can be obtained before
the coagulation of the blood. ---> What is the difference between serum and
plasma? How are both obtained?
When on a carb-free diet, glucose is not readily available and needs to be made by
gluconeogenesis in the liver. Amino acids are used in the liver for this process. They
are first converted into Acetyl-CoA and can then go through gluconeogenesis. --->
Current recommendations advise to use extra protein or amino acid supplements
when on a carb-free diet. Why is this essential, and for which process in the liver are
they used?
- Insulin stimulates the uptake of glucose (GLUT4 receptors), as well as glycolysis
and lipolysis and glycogen synthesis. Insulin inhibits glycogenolysis.
- Glucagon activates gluconeogenesis and glycogenolysis, as well as lipogenesis.
Glucagon inhibits glycolysis by inhibiting hexokinase and glucokinase. ---> What
are the effects of insulin and glucagon on fat cells and on muscle cells?
When Acetyl-CoA is in high concentration pyruvate carboxylase is activated. This
signifies that products have been converted into acetyl coa and can be further
