Why does the OH group add to the b-carbon rather than to the a-carbon in the second reaction in the
b-oxidation of fats?
B carbon has a partial positive charge (therefore the nucleophilic OH group attracted to the B carbon)
16 carbon fatty acid makes how many acetyl-CoAs?
8 (cause the acyl group of acetyl CoA has 2 carbons)
B oxidation of 16 carbon compound
7 (each round yields one and you can cleave it 7 times cause each round takes out two carbons)
The oxidation of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate is an endergonic reaction, but the flow through this point in glycolysis proceeds smoothly. How is the unfavorable equilibrium constant overcome?
the reaction that follows is super exergonic so it balances out
How many molecules of NAD + are required to convert one molecule of glucose to pyruvate
2 (each glucose is converted into 2 glyceraldehyde 3-phosphate and each of these need one molecules of NAD+ to be made into one pyruvate each)
What functional group of pyruvate is reduced when pyruvate is converted to lactate?
ketone
What coenzyme is required to convert pyruvate to acetaldehyde?
thiamine pyrophosphate
What compound is formed when alanine is transaminated?
pyruvate
What functional group of isocitrate is oxidized in the third reaction of the citric acid cycle?
secondary alcohol
The citric acid cycle is also called the tricarboxylic acid cycle (or TCA cycle). Which of the citric acid cycle intermediates are tricarboxylic acids?
citrate and isocitrate
Which of the eight enzymes in the citric acid cycle has a name that refers to the reverse reaction?
succinyl-CoA synthetase
Which of the ten enzymes in glycolysis has a name that refers to the reverse reaction?
aldolase, pyruvate kinase, phosphoglycerate kinase
each NADH makes
2.5ATP
each FADH makes
1.5 ATP
How many molecules of ATP are obtained from the conversion of one molecule of glycerol to pyruvate NOT including the fourth stage of catabolism?
net: one (glycerol to dihydroxyacetone phosphate consumes one atp and then dihydroxyacetone phosphate to pyruvate produces two ATP)
How many molecules of ATP are obtained from the conversion of one molecule of glycerol to pyruvate INCLUDING the fourth stage of catabolism?
the one ATP from the first three stages and then the two new NADH making a total of 6 (cause one NADH formed from the conversion of one molecule of glycerol to dihydroxyacetone phosphate and one formed formed from dihydroxyphosphate to pyruvate)
What is the name of the enzyme that converts glycerol to glycerol-3-phosphate?
glycerol kinase
What is the name of the enzyme that converts phosphatidic acid to 1,2-diacylglycerol?
phosphatidic acid phosphate
Hexokinase
-first enzyme that catalyzes irreversible reaction in glyclolysis
-regulatory enzyme inhibited by too much glucose-6-phosphate
-feedback inhibitor
-glucose to glucose-6-phosphate
Phosphofructokinase
-high concentration of ATP says that more ATP is being produced than is being used so no need to break down glucose anymore
-inhibits the enzyme by binding to it and causing a conformational change that decrease it's affinity for the substrate (allosteric
Pyruvate carboxylase
-first enzyme that catalyzes irreversible reaction in gluconeogenesis
-acetyl CoA is allosteric activator of pyruvate carboxylase and a feedback inhibitor of pyruvate dehydrogenase
-high concentration of acetyl CoA signals there is no need for energy so p
A phosphoanhydride bond is known as a ________ bond.
high energy
ATP reacts readily in enzyme-catalyzed reactions, but it reacts quite slowly in the absence of the enzyme. Which of the following best accounts for the kinetic stability of ATP?
ATP is negatively charged at physiological pH and thus repels the approach of nucleophiles.
metal ions is found at the active site of ATP-requiring enzymes and facilitates the approach of nucleophiles to the phosphorus atoms?
Mg2+
Which of the following statements best explains the source of energy behind the ATP molecule?
Energy is released when a phosphoanhydride bond of ATP is broken.
In order to enter the citric acid cycle, a compound must be either an intermediate of the cycle or what other two molecules?
aacetyl-CoA or pyruvate
Most of the energy provided by chemical nutrients is provided in what stage of catabolism?
fourth stage
What class of enzyme puts a phosphoryl group on its substrate?
kinase
Why does the OH group add to the ?-carbon rather than to the ?-carbon in the second reaction in the ?-oxidation of fats?
The ?-carbon of the ?,?-unsaturated carbonyl compound has a partial positive charge
How many molecules of NAD+ are required to convert one molecule of glucose to pyruvate?
2
In glycolysis, each molecule of glucose is converted to two molecules of
pyruvate
In glycolysis, conversion of a molecule of glucose into 2 molecules of pyruvate results in a net production of ________ molecules of ATP.
2
Under anaerobic conditions, what compound in mammalian cells is used to oxidize NADH back to NAD+ so that glycolysis can continue?
pyruvate
Under anaerobic conditions in yeast cells, pyruvate is converted to acetaldehyde and ________, with the acetaldehyde being subsequently converted to ________ in a step that oxidizes NADH to NAD+.
carbon dioxide, ethanol
Acetyl-CoA enters the citric acid cycle by reacting with ________ to form ________.
oxaloacetate,citrate
In the citric acid cycle, the acetyl group of each molecule of acetyl-CoA is converted into two molecules of
co2
How many citric acid cycles would be needed to produce nine molecules of NADH?
three (each cycle makes three itself)
How many citric acid cycles would be needed to produce nine molecules of FADH2?
9 (each cycle only makes one)
In the citric acid cycle, FAD oxidizes succinate to
fumerate
each round of the citric acid cycle makes
three molecules of NADH
each round of the citric acid cycle makes how many molecules of FADH2?
1
In the metabolism of fatty acids through ?-oxidation, each passage through the four reactions
removes two carbons
What type of enzyme is needed to catalyze the reaction in which 3-phosphoglycerate is converted to 2-phosphoglycerate?
-mutase
-catalyzes a reaction in which the product of the reaction is an isomer of the substrate.
The synthesis of which nonessential amino acid is impeded by the disease phenylketonuria (PKU)?
tyrosine
The oxidation of a fatty acid to an ?,?-unsaturated fatty acid is accomplished using ___________ as the oxidizing agent.
FAD
How many molecules of ATP are produced in glycolysis?
2 (each molecule consumes two and forms four)
What is the only non-citric acid cycle intermediate that can enter the citric acid cycle?
acetyl-CoA
What two steps are involved in the conversion of citrate to isocitrate in the citric acid cycle?
The first step is a dehydration; the second step is the conjugate addition of water
anabolism
simple molecules + energy ? complex molecules
Which of the following does not account for the large amount of energy released when ATP reacts with a nucleophile?
greater solubility of the products
The enzyme that catalyzes the reaction of ATP with glucose to form glucose-6-phosphate is a(n) _____
kinase
What two steps are involved in the conversion of oxaloacetate to citrate to in the citric acid cycle?
The first step is an aldol addition; the second step is hydrolysis of a thioester
Which reactions in the citric acid cycle form a product with a new asymmetric center?
conversion of fumarate to (S)-malate
conversion of citrate to isocitrate
What are four possible fates of pyruvate in a mammalian cell?
to be converted to lactate
to be converted to acetyl-CoA
to be converted to oxaloacetate
to be converted to alanine
How would blood glucose levels be affected before and after a 24-hour fast if there is a deficiency of fructose-1,6-bisphosphatase?
At the beginning of a fast, blood glucose level would be normal. After a 24-hour fast, blood glucose level would be very low.
When pyruvate is reduced by NADH to lactate, which hydrogen in lactate comes from NADH?
hydrogen on the alpha carbon
Which of the ten reactions in glycolysis are
a. phosphorylations?
reactions 1 and 3
Which of the ten reactions in glycolysis are
b. isomerizations?
reactions 2, 5 and 8
Which of the ten reactions in glycolysis are
c. oxidations?
reaction 6
Which of the ten reactions in glycolysis are
d. dehydrations?
reaction 9
Which reaction links glycolysis and the citric acid cycle? and how is the reaction catalyzed?
conversion of pyruvate to acetyl-CoA, catalyzed by the pyruvate dehydrogenase complex
If the phosphorus atom in 3-phosphoglycerate is radioactively labeled, where will the label be when the reaction that forms 2-phosphoglycerate is over?
label will be on the phosphate group attached to the enzyme (phosphoglycerte mutase) that catalyzes the isomerization of 3-phosphoglycerate to 2-phosphoglycerate
Which carbon atoms of glucose end up as a carboxyl group in pyruvate?
C3 and C4
Which carbon atoms of glucose end up in ethanol under anaerobic conditions in yeast?
half from C1 and C2 and the other half from C5 and C6
How many molecules of acetyl-CoA are obtained from the b-oxidation of one molecule of a 16-carbon saturated fatty acyl-CoA?
8
How many molecules of CO2 are obtained from the complete metabolism of one molecule of a 16-carbon saturated fatty acyl-CoA?
16
How many molecules of ATP are obtained from the b-oxidation of one molecule of a 16-carbon saturated fatty acyl-CoA?
0
How many molecules of NADH and FADH2 are obtained from the b-oxidation of one molecule of a 16-carbon saturated fatty acyl-CoA?
7 and 7 cause each cleavage makes one
How many molecules of ATP are obtained from the NADH and FADH2 formed in the b-oxidation of one molecule of a 16-carbon saturated fatty acyl-CoA?
28 (based on the 2.5 for NADH and 1.5 for FADH)
step 1 of TCA
oxaloacetate + acetyl-CoA -> citrate
step 2 of TCA
citrate --> isocitrate
isomerzation reaction, mutase is the type of enzyme that does it
E2 dehydration followed by conjugate addition of water
step 3 of TCA
isocitrate --> a-ketoglutarate
first molecule of CO2 released
step 1: secondary alcohol group is oxidized to a ketone by NAD+
step 2: ketone loses CO2 with Mg2+ acting as a catalyst
step 4 of TCA
a-ketoglutarate --> succinyl-CoA
releases the second molecule of CO2, required PDC , results in the overall transfer of an acyl group to CoASH
step 5 of TCA
succinly-CoA --> succinate
step 1: hydrogen phosphate reacts with succinyl CoA to form in a nucleophilic acyl subsition to form an intermediate which will then transfer its phosphate group to ADP
step 6 of TCA
succinate --> fumerate
FAD oxidizes
step 7 of TCA
fumerate --> (S)-malate
conjugate addition of water to the double bond
step 8 of TCA
(S)-malate --.> oxaloacetate
oxidation of the secondary alcohol group of (s)-malate by NAD+ AND THE CYCLE STARTS AGAIN YAAAY
four steps of beta oxidation
oxidation, conjugate addition of water, oxidation and then reverse claisen condensation
step 1 of Glycolysis
Glucose --> Glucose 6-phosphate.
Uses hexokinase enzyme.
ATP --> ADP
step 2 of Glycolysis
Glucose 6-phosphate <--> Fructose 6-phosphate
Uses phosphohexose isomerase enzyme
step 3 of Glycolysis
Fructose 6-phosphate --> Fructose 1,6-bisphosphate
Uses PFK-1 (phosphofructokinase-1) enzyme.
ATP --> ADP
Step 4 of Glycolysis
Fructose 1,6-bisphosphate <-> dihydroxyacetone + glyceraldehyde 3-phosphate.
Uses aldolase enzyme.
the dihydroxyacetone will make G3P in step 5
Step 5 of Glycolysis
Dihydroxyacetonephosphate <--> glyceraldehyde 3-phosphate
Uses triose phosphate isomerase enzyme, forms an enediol that then forms G3P
Step 6 of Glycolysis
Glyceraldehyde 3-Phosphate <--> 1,3-biphosphoglycerate.
Uses G3P dehydrogenase enzyme.
NAD+ <--> NADH
Step 7 of Glycolysis
1,3-bisphosphoglycerate + ADP <--> 3-phosphoglycerate + ATP
Uses phosphoglycerate kinase enzyme.
Step 8 of Glycolysis
3-phosphoglycerate <--> 2-phosphoglycerate
Uses phosphoglycerate mutase enzyme.
Step 9 of Glycolysis
2-phosphoglycerate <--> Phosphoenolpyruvate (PEP)
Uses enolase enzyme.
Dehydration reaction (loss of water).
Step 10 of Glycolysis
phosphoenolpyruvate to pyruvate