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BIOC 431-Exam III Questions with Correct Answers
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BIOC 431-Exam III Questions with Correct Answers
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BIOC 431-Exam III Questions withCorrect Answers
role of hydrolases for converting carbohydrates into intermediates for glycolysis -
Answer-to break glycosidic bonds using water
role of kinases for converting carbohydrates into intermediates for glycolysis - Answer-to
phosphorylate the monosaccarides
role of isomerases for converting carbohydrates into intermediates for glycolysis -
Answer-to change monosaccharides into glucose or fructose
role of dehydrogenases for converting carbohydrates into intermediates for glycolysis -
Answer-to make sugars from sugar-alcohols
example of hydrolase and role - Answer-amylase- hydrolyzes the internal glycosidic
linkages of starch producing short polysaccharide fragments or oligosaccharides
invertase- breaks sucrose into fructose and glucose
lactase- breaks lactose into galactose and glucose
role of fructose - Answer-metabolized primarily in the liver to replenish glycogen
and triglycerides, however most cells only weakly absorb fructose
pathway to fructose 6-phosphate - Answer-mannose --> (by hexokinase) mannose-6-
phosphate --> (phosphomannose isomerase) fructose 6-phosphate
glycerol - Answer-glycerol -->(glycerol transferase) glycerol-3-P --> (glycerol-3-P
dehydrogenase) dihydroxyacetone-P
galactose - Answer-(mutarotase) --> galactose --> (galactokinase) gal-1-P --> (UDP
galactose epimerase) UMP-P-Glc + (Gal‐1‐P uridyltransferase) UMP-P-Gal -->
(hydrolase) Glc-1-P
Source of UDP‐Glucose - Answer-glucose-1-P + Uridine Triphosphate --> (Glucose‐1‐P
uridylyltransferase) UDP‐Glucose + Pyrophosphate (PPi)
breakdown of Pyrophosphate (PPi) - Answer-(Pyrophosphatase) --> Pi (free phosphate)
phosphoglucomutase role; What compound might this
enzyme need small amounts
of to work? - Answer-glucose-1-P --> glucose 6-P; glucose-1,6-biphosphate
What enzyme activities do we need for dietary intake? - Answer-hydrolysis
1. Starch or glycogen + H2O--> Maltose
,2. Maltose (glucose‐a‐1,4‐a‐glucose) + H2O --> (maltase) 2 Glucose)
What class of enzyme? - Answer-hydrolyases
Phosphorolysis of Intracellular Glycogen, what class of enzyme - Answer-Glycogen
phosphorylase, Transferase
Fermentation - Answer-Lactate dehydrogenase
The Cori Cycle: - Answer--Allows Lactate dehydrogenase to run in reverse by
changingthe cellular conditions.
-The cellular conditions change because the cell changes.
-The liver was not challenged by exercise, and maintained a
high NAD+/NADH ratio.
Ethanolic Fermentation - Answer-Has been a huge impact on the human condition.
A current interest in renewable fuels
Pyruvate --> (Pyruvate
decarboxylase-lyase) Acetaldehyde --> (Alcohol
Dehydrogenase-oxidoreductase) Ethanol
-example of decarboxylation of a a‐keto acid.
TPP - Answer-TPP is a carrier cofactor, stabilizes carbocations
Pyruvate dehydrogenase - Answer-takes place in mitochondria, NAD+ and CoA‐SH are
co‐substrates
TPP, lipoic acid, and FAD are prosthetic groups
Structure of Coenzyme A - Answer-Coenzymes are not a permanent part of the enzyme
structure.
- They associate, fulfill a function, and dissociate
The function of CoA is to accept and carry carbonyl‐containing molecules
Structure of Lipoic acid - Answer-Prosthetic groups are strongly bound to the protein
Lipoic acid is covalently linked to the enzyme via a lysine residue
Flavin cofactors - Answer--allow single electron transfers
-Permits the use of molecular oxygen as an ultimate electron acceptor
• flavin‐dependent oxidases allow acceptance of ONE or TWO protons and electrons
-Flavin cofactors are tightly bound to proteins (prosthetic groups)
Does the degradation of ingested starch to form glucose that can enter glycolysis
require an input of
energy? Explain. - Answer-No, phosphorolysis, addition of water
example of transferase
, Is it more energetically expensive to feed monosaccharides other than glucose into
glycolysis? Explain. - Answer-
Why is the cell's ability to regenerate NAD+ critical to glycolysis? Which glycolysis
enzyme requires NAD+? - Answer-failure to regenerate NAD+ would leave the cell with
no electron acceptor for the oxidation of glyceraldahyde 3-phosphate, and glycolysis
would stop
Do all organisms perform alcohol fermentation and lactic acid fermentation? - Answer-
Yes-Lactic acid fermentation is where sugars (glucose,fructose,sucrose) are converted
into energy & lactate. Alcohol fermentation is where sugars (glucose, fructose, sucrose)
are converted into energy and produce ethanol and carbon dioxide.
How does the Cori cycle relate to athlete recovery from sprints? - Answer-There are
some instances in life, however, such as sprinting to catch a bus or a 5 Rep Max Back
Squat, that might require ATP (energy) production faster than our bodies can deliver
oxygen. In these instances, muscles generate energy anaerobically, meaning "without
oxygen". Without oxygen, the pyruvate breaks down to a substrate called lactate.
1.In the presence of oxygen, lactate unbinds from the acid inside the muscle and it is
drawn into the bloodstream where it binds to oxygen.
2. The oxygen bound lactate is transported through the blood to the liver.
3. In the liver, the lactate is ultimately converted back to glucose.
What structural aspect of TPP allows it to act as an "electron sink"? - Answer-the
thiazolium ring
In general, what is the role of TPP in biological reactions? - Answer-TPP works as a
coenzyme in many enzymatic reactions, such as:
- Pyruvate dehydrogenase complex (AcetylCoA synthesis for acetylcholine)
pyruvate + CoA --> acetylCoA
TPP activates:
-the Krebs cycle (enzymes 1-3) and reduces glucose and pyruvate availability for
synthetic pathways
The oxidative decarboxylation of pyruvate (i.e., pyruvate dehydrogenase), is a highly
exergonic reaction.
How is the energy released by this reaction conserved? - Answer-The transfer of
electrons from NADH to oxygen generates 2.5 molecules of ATP per pair of electrons.
The complex cannot reattach radioactivity labeled CO2 to acetyl-CoA to yield carboxyl-
labeled pyruvate.
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