Carb- Book Qs

• The primary site within the human body where carbohydrate digestion occurs is the small intestine
• Mouth is the first site within the human body where breaking of polysaccharide glycosidic bonds occurs
• The enzymes that convert disaccharides to monosaccharides are associated with intestinal mucosal cells
• ATP is needed for monosaccharides to enter the bloosdstream
• The overall process of glycolysis converts a C6 molecule into two C3 molecules
• 4 and 6 are the total number of steps in the C6 and C3 stages of glycolysis respectively
• The first two intermediates in the process of glycolysis are glucose 6-phosphate and glucose 1-phosphate
• Pyruvate, the end product of glycolysis, is a three-carbon keto acid
• When one glucose molecule is processed through the glycolysis pathway, relative to ATP production/consumption, there is a net gain of two ATP
• Steps 1 and 3 are the two steps of glycolysis where ATP is converted to ADP
• In the human body, under oxygen-rich and oxygen-poor conditions, respectively, pyruvate is converted t acetyl CoA and lactate
• The major purpose of lactate fermentation is the production of NAD+
• Lactate Fermentation is the process involves in the conversion of a C3 molecule to another C3 molecule
• Accumulation of lactate in muscle cells is the cause of stiffness and soreness after vigorous exercise
• Intestinal mucosal cells are the sites where hydrolysis of disaccharides, effected by the enzymes maltase, sucrase, and lactase, occurs.
• The small intestine is the location where pancreatic digestive enzymes convert poly- saccharides to disaccharides.
• Digestion of carbohydrates begins in the mouth, where salivary enzymes convert some polysaccharides to smaller polysaccharides through breakage of glycosidic linkages.
• Intestinal mucosal cells are the sites where disaccharides, through hydrolysis, are converted to the monosaccharides glucose, fructose, and galactose.
• What effect does gastric juice in the stomach have on dietary polysaccharides?

  has no effect on polysaccharides
• Specify the number of carbon atoms present and the number of phosphate groups present in each of the following glycolysis intermediates: Glucose 6-phosphate

  Glucose is a hexose. Glucose 6-phosphate is a Co molecule that carries one phosphate group, attached to carbon 6.
• Specify the number of carbon atoms present and the number of phosphate groups present in each of the following glycolysis intermediates: Fructose 1,6-bisphosphate

  Fructose is a hexose. Fructose 1,6-bisphosphate is a Co molecule that carries two phosphate groups, one attached to carbon 1 and the other attached to carbon 6.
• Specify the number of carbon atoms present and the number of phosphate groups present in each of the following glycolysis intermediates: Glyceraldehyde 3-phosphate

  Glyceraldehyde 3-phosphate is a C3 molecule with one phosphate group, attached to carbon 3
• Specify the number of carbon atoms present and the number of phosphate groups present in each of the following glycolysis intermediates: 3-Phosphoglycerate

  3-Phosphoglycerate, like glyceraldehyde, is a C3 molecule. It has one phosphate group, attached to carbon 3.
• Indicate at what step in the glycolysis pathway each of the following events occurs: First phosphorylation of ADP occurs.

  Phosphorylation of ADP produces ATP with the added phosphate coming from a glycolysis intermediate. This process occurs for the first time in Step 7, where 1,3-bisphosphoglycerate is converted to 3-phosphoglycerate. It occurs a second time in Step 10.
• Indicate at what step in the glycolysis pathway each of the following events occurs: First "energy-rich" compound is produced.

  In carbohydrate metabolism, an "energy-rich" compound is a high-energy phosphate. Two such compounds are produced during glycolysis, the first in Step 6 and the second in Step 9. The Step 6 compound is 1,3-bisphosphoglycerate.
• Indicate at what step in the glycolysis pathway each of the following events occurs: Second "energy-rich" compound undergoes reaction.

  The second "energy-rich" compound is phosphoenolpyruvate, which is produced in Step 9 and undergoes reaction in Step 10.
• Indicate at what step in the glycolysis pathway each of the following events occurs: First isomerization reaction occurs.

  There are three isomerization reactions in glycolysis. They occur in Steps 2, 5, and 8. In the first occurrence, Step 2, glucose 6-phosphate is converted to fructose 6-phosphate. Glucose and fructose are isomeric hexose molecules
• A kinase is an enzyme that is involved with phosphate group transfer. The phosphofructo portion of the enzyme name refers to a fructose phosphate. Transfer of a phosphate group to a fructose phosphate occurs in Step 3. Fructose 6-phosphate is converted to fructose 1,6-bisphosphate.
• A mutase is an enzyme that shifts the position of a functional group within a molecule. Such a functional group shift occurs in Step 8, where 3-phosphoglycerate is isomerized to 2-phosphoglycerate. The phosphoglycerol portion of the enzyme name indicates that a glycerate phosphate is the substrate for the enzyme.
• A triosephosphate isomerase effects the isomerization of a triose. Such a process occurs in Step 5, where dihydroxyacetone phosphate (a ketone) is converted to glyceraldehyde 3-phosphate (an aldehyde). Ketones and aldehydes with the same number of carbon atoms are often isomers.
• The only enol species in glycolysis is the compound phosphoenolpyruvate produced in Step 9 through a dehydration reaction that introduces a carbon-carbon double bond in the molecule. An enolase effects such a change.
• Which of the following statements concerning glycolysis is correct?

  a.The pathway for the process is a cyclic pathway.

  b. It occurs in the mitochondrial matrix.

  c. Molecular O2 is not needed for the process to occur.

  d. no correct response

  C
• CO2 is a product for both acetyl CoA formation and ethanol fermentation. In both of these processes, the C3 pyruvate is converted to a C2 species and CO2 No CO2 production occurs during lactate fermentation, as C3 pyruvate is converted to C3 lactate.
• The only pathway that produces a C3 molecule is lactate fermentation. In the other two pathways, a C2 molecule and CO2 are produced.
• NAD, as an oxidizing agent, is needed in pathways that function under aerobic conditions. NADH, as a reducing agent, is needed in pathways that function under anaerobic conditions. The only pathway that involves aerobic conditions is acetyl CoA formation.
• Alcohol fermentation, an anaerobic process, produces ethanol, a C2 molecule. The other anaerobic process, lactate fermentation, produces the C3 molecule lactate.
• In which of the following conversions is CO2 produced?

  a.lactate to pyruvate

  b. pyruvate to acetyl CoA

  c. pyruvate to lactate

  d. no correct response

  B
• For the complete oxidation of a glucose molecule, the majority of the ATP produced comes from which of the following phases in the oxidation process?

  a.glycolysis

  b. citric acid cycle

  c. electron transport chain

  d. no correct response

  C
• The net yield of ATP for the complete oxidation of one molecule of glucose is 30 ATP
• The net yield of ATP per glucose molecule in the process of glycolysis is

  a.12 ATP

  b. 14 ATP

  c. 18 ATP

  d. no correct response

  D