What is and who founded the vitalistic dogma
Fermentation of sugars to alcohol inextricably tied to living cells founded by Louis Pasteur in 1860
How did metabolism become chemistry?
Serendipitous finding by Hans and Eduard Buchner in 1897 with cell-free yeast extracts that fermentation could take place outside the cell.
What is the underlying unity in biochemistry
Studies of muscle extracts showed that many of the reactions of lactic acid fermentation were shared with alcoholic fermentation
Fermentation of produces what?
Ethanol and lactate
True or false: Glycolysis is an anaerobic process
True, oxygen is not required to complete glycolysis
What are the net products of the glycolysis of one glucose molecule?
2 pyruvate, 2 ATP, and 2 NADH+
In the lecture, glycolysis is broken into 3 stages. What happens in the 1st stage?
In the lecture, glycolysis is broken into 3 stages. What happens in the 2nd stage?
In the lecture, glycolysis is broken into 3 stages. What happens in the 3rd stage?
In glycolysis, glucose is phosphorylated to glucose 6-phosphate by________ and ATP
hexokinase
True or false: Glucose-6-phosphate is negatively charged and can pass back out through the plasma membrane
False: glucose-6-phosphate cannot pass through the plasma membrane; this is why glucose is quickly phosphorylated
Glucose-6-phosphate is converted to Fructose-6-phosphate by what enzyme?
Phosphoglucose isomerase
fructose 6-phosphate is phosphorylated to fructose 1,6-bisphosphate by ___________ and ATP
phosphofructokinase
True or false: phosphofructokinase contains additional binding sites for allosteric effectors
True. phosphofructokinase has several activators and inhibitors
The splitting of fructose 1,6-bisphosphate to DHAP and GAP is carried out by which enzyme?
Aldolase
How many glyceraldehyde-3-phosphates are produce per glucose?
Two of these 3 carbon units are produced for every six carbon glucose
What is the function of NAD+ in glycolysis?
Oxidizing agent and cofactor allowing inorganic phosphate to be added to GAP
3 stages of glycolysis are essentially irreversible. What are the enzymes at these 3 stages?
Hexokinase, phosphofructokinase, pyruvate kinase. Note: all are kinases
True or false: ATP acts as an allosteric activator for phosphofructokinase
False: ATP act as an allosteric inhibitor of phosphofructokinase
Name 3 activators of phosphofructokinase
AMP, insulin, fructose 2,6-bisphosphate
Which product (other than ATP) of the TCA cycle inhibits phosphofructokinase?
Citrate
What are the allosteric effectors of pyruvate kinase? specify activator or inhibitor
Alanine (inhibitor), Fructose 1,6-bisphosphate (activator)
True or false: The phosphorylation of pyruvate kinase inhibits the enzyme
True
Which hormone stimulates the expression of pyruvate kinase by effecting transcription?
Insulin
Where does galactose enter the glycolytic pathway?
Where does fructose from adipose tissue enter the glycolytic pathway?
Where does fructose from the liver enter the glycolytic pathway?
Why is there less regulation on fructose metabolism?
Fructose from the liver bypasses regulation of phosphofructokinase, does not lead to F-2,6-BP, hence less regulation on fructose metabolism
How is fructose modified for entry into the glycolytic pathway as GAP and DHAP?
Why does much fructose go to adipose tissue and converted to fat instead of being metabolized like glucose?
Hexokinase preferentially utilizes glucose rather than fructose
What is a common cause of galactosemia?
deficiency of galactose 1-phosphate uridyl transferase activity, which catalyzes conversion of galactose to glucose 6-phosphate
What are some symptoms of galactosemia?
vomiting and diarrhea after consumption of milk by infants; can eventually lead to mental retardation
Lactose intolerance is commonly caused by a deficiency of which enzyme?
Lactase
True or false: Fermentations cannot provide energy in the absence of oxygen
False. Thats exactly what it does!
Which process is used by humans to get energy from pyruvate in the absence of oxygen?
The Cori Cycle
Cori cycle reduces pyruvate from glycolysis to lactic acid, producing ________ for use in glycolysis
NAD+
True or false: NAD+ is needed to complete glycolysis, once all NAD+ reduced to NADH, glycolysis stops
True
How is NAD+ regenerated under oxygen debt?
The Cori Cycle
Lactate is converted to pyruvate through gluconeogenesis for another round of glycolysis in which tissue?
The Liver
Which tissue other than the liver shares the burden when the muscles are under oxygen debt?
Cardiac tissue
True of false: Cardiac cells can utilize lactate for use in the citric acid cycle and oxidative phosphorylation
True
Glucose synthesis occurs mostly in _________?
The Liver
What are sources of precursor molecules for gluconeogenesis?
amino acids (from muscle breakdown)
lactate (lactic acid)
glycerol (from fat breakdown)
The first enzyme of gluconeogenesis, pyruvate carboxylate, is located where?
In the mitochondria
The last enzyme of gluconeogenesis, glucose-6-phosphatatse is located where?
membrane bound in the endoplasmic reticulum
True or false: most enzymes of gluconeogenesis are located in the mitochondrial matrix?
False. Except for pyruvate carboxylate and glucose-6-phosphatase, all gluconeogenesis enzymes are cytoplasmic.
What is the product of pyruvate carboxylase?
Oxaloacetate
Oxaloacetate in gluconeogenesis is reduced to what?
Malate
What four enzymes are regulators of gluconeogenesis?
Phosphoenolpyruvate carboxykinase, pyruvate carboxylase, fructose 1,6-bisphosphatase, and glucose 6-phosphatase
Gluconeogenesis and glycolysis are ___________ regulated
reciprocally
Which tissues have glucose 6-phosphatase?
Liver and kidneys
True or false: Most gluconeogenesis reactions end at glucose 6-phosphate and not glucose
True
Which enzyme and its associated components are only located in the endoplasmic reticulum.
glucose 6-phosphatase
How does the normal serum glucose level compare to GLUT1 and 3 Km present in all mammalian tissue?
it is about 4.8mM above Km
How does the normal serum glucose level compare to GLUT4 Km present in muscle and fat tissue?
the same
How does the normal serum glucose level compare to Km of GLUT2 present in liver and pancreatic beta-cells?
serum glucose level is below the Km
True or false: GLUT5 in the small intestine is primarily a fructose transporter
True
Under strict anaerobic conditions, the catabolism of one glucose molecule would yield a net of______________________?
2 ATP and 2 lactic acid molecules
Consider the conversion: alanine to lactic acid to glucose. This is an example of___________?
gluconeogenesis
Which of the following enzymes does not function in association with a membrane?
A. Permease
B. Na+/K+ ATPase
C. Adenylate cyclase
D. Phosphofructokinase
E. Coenzyme Q reductase
Phosphofructokinase
Insulin increases the activity of which of the following?
A. Enolase
B. Phosphorylase a
C. Phosphofructokinase
D. Glucose-6-phosphatase
E. Fructose 1-6 diphosphatase
Phosphofructokinase
ATP inhibits phosphofructokinase even though ATP is also a substrate for the enzyme. This phenomenon is an example of _______________?
allosteric inhibition