Glycolysis

Biochemistry and Genetics 1 Dr. Grogan's Material for Mini-II 5 questions Answer key is at the end IN REVERSE ORDER!!! 1) Mice are made which have a selective knock-out of the GLUT4 transporter in muscle. The mice survive, but have unusual glucose metabolism. These mice would MOST LIKELY DIFFER from normal mice by having: A) glucose uptake only by liver parenchymal cells B) post-excercise plasma hypoglycemia C) failure of all insulin-dependent responses, and insulin-resistance D) post-prandial plasma hyperglycemia E) failure to secrete enough insulin from pancreas after meals 2) While glucokinase is an important enzyme in liver, it is also present in pancreatic β-cells. A patient is shown to have low glucokinase activity in pancreatic β-cells by enzymatic analysis. This patient is MOST LIKELY to? A) deliver more GLUT4 receptor to the plasma membrane of muscle cells B) transport too much glucose into pancreas, reducing uptake by other tissues C) develop a type of insulin-resistant diabetes mellitus D) be unable to utilize glucose in pancreas E) secrete less insulin when glucose levels increase to high levels 3) In Tauri Disease (Glycogen Storage Disorder Type VII) nausea, vomiting, myoglobinuria, cramping and other symptoms develop due to a mutation of phosphorfructokinase-1 (PFK-1). Symptoms usually appear in these patients after intense excercise. Why? A) glucose 6-phosphate is diverted to storage in muscle and cannot be regenerated B) muscle PFK-1 is not regulated as occurs in other tissues like liver C) lactate accumulation in excercising muscle has a positive allosteric effect on PFK-1 D) glucose dephosphorylation occurs which reduces net ATP yields from glycolysis E) muscle has an extreme requirement for ATP from anaerobic glycolysis in excercise 4) A deficiency of Triose Phosphate Isomerase (TPI) often leads to hemolytic anemia. Why are erythrocytes particularly susceptible to low levels of this enzyme? (Note - progressive neurodegenerative disorders also develop in severe TPI deficiency)

A) muscle and other tissues do not require this enzyme B) erythrocytes cannot make any ATP without this enzyme C) the PFK-1 reaction becomes reversible with high fructose 2,6 bis-P concentrations D) cells are forced to make ATP, without oxygen, in order to maintain ion gradients E) hemoglobin function depends on adequate levels of glyceraldehyde 3phosphate 5) Analysis of a patient's blood shows chronic hyperlactatemia (high lactic acid levels). This suggests that the patient's oxidation of glucose to CO2 is: A) the result of a high ATP to ADP ratio B) utilizes both glycolytic and TCA (Kreb's cycle) enzymes equally C) the result of a deficiency of lysosomal enzymes D) not complete E) blocked by the action of glucagon Answer Key (in reverse order): D, B, E, E, D