Chapter 22

Based on 3 ATP molecules per NADH and 2 ATP molecules per FADH2 , the complete catabolism of 1 molecule of glucose produces _________ ATP Molecules

3 ATP are generated per NADH 2 ATP are generated per FADH2

What is the Net Result from the Electron Transport Chain?

34 ATP

What is the NET Result of it Altogether?

38 ATP

What is the Net Result in Anaerobic Glycolysis?

2 ATP 2 NADH 2 Pyruvate

What is the Net Result from the Citric Acid Cycle?

2 ATP 6 NADH 2 FADH2 4 CO2

What is the Net Result in Acetyl-Coenzyme A production?

2 CO2 2 NADH

What is a potential limiting factor that involves glycolysis and NAD+/NADH ?

A continuous reaction in glycolysis depends upon the availability of the oxidized form of the electron carrier NAD+. Thus, NADH must be continuously oxidized back into NAD+ in order to keep this step going. If NAD+ is not available, the second half of glycolysis slows down or stops. If oxygen is available in the system, the NADH will be oxidized readily, though indirectly, and the high-energy electrons from the hydrogen released in this process will be used to produce ATP. In an environment without oxygen, an alternate pathway (fermentation) can provide the oxidation of NADH to NAD+.

Digestion:

A general term for the breakdown [catabolism] of food into small molecules.

What is the name for when there IS oxygen?

Aerobic

What is the name for when there is NO oxygen?

Anaerobic

Is Glycolysis Aerobic or Anaerobic?

Anaerobic (no oxygen) though it can do both - but it is able to proceed without oxygen

Which is older Aerobic or Anaerobic pathways?

Anaerobic pathways (no oxygen) are the oldest.

As glucose and glycogen reserves are exhausted, metabolism turns to breakdown of __________.

As glucose and glycogen reserves are exhausted, metabolism turns to breakdown of Proteins. Protein is used at a rate as high as 75 g/day

What is the path for generating energy from fat?

Catabolism of fatty acids to acetyl-CoA, oxidation of acetyl-CoA via the citric acid cycle, and production of ATP energy from the electron transport is the path for generating energy from fat.

The complete oxidation of glucose produces 6 molecules of carbon dioxide...What stages of Catabolism are each produced?

Consider (in order) are (#1) Glycolysis, (#2) The Conversion of Pyruvate to Acetyl-CoA, and (#3) The Citric acid cycle. There is no need to consider oxidative phosphorylation because glucose is completely oxidized at the end of the citric acid cycle. (#1) Glycolysis: No molecules of carbon dioxide are produced during glycolysis (#2) The Conversion of Pyruvate to Acetyl-CoA: Conversion of one molecule of pyruvate to one molecule of acetyl-CoA yields one molecule of carbon dioxide. (#3) The Citric acid cycle: In the citric acid cycle, two molecules of carbon dioxide are released for each molecule of acetyl-CoA oxidized. **Because each glucose molecule produces two pyruvate molecules, the total is three molecules twice = 6 molecules of CO2)**

Overall Results of the citric acid cycle:

Conversion of 2 Acetyl CoA molceules Net production of 2 ATP molecules (one per acetyl CoA) Production of 6 molecules of reduced coenzyme NADH from NAD+ (2 x three) And 2 molecules of FADH2 (one per acetyl CoA)

Overall Results of Glycolysis:

Conversion of glucose to two pyruvate molecules Net production of 2 ATP molecules Production of two molecules of reduced coenzyme NADH from NAD

What is pur largest energy reserve?

Fats are our largest energy reserve. But...adjusting to dependence on fat for energy takes several days because there is no direct pathway for generating glucose from the fatty acids in fats.

Fructose is converted to ______________ in 2 ways.

Fructose is converted to glycolysis intermediates in 2 ways. Fructose 6-phosphate is the substrate for step 3 of glycolysis; glyceraldehyde 3-phosphate is the substrate for step 6

What absorbs fructose?

GLUT2 (high capacity , low specificity, insulin independent) and GLUT5

What absorbs glucose?

GLUT4 (and GLUT1) absorb glucose.

Galactose

Galactose from the hydrolysis of the disaccharide lactose is converted to glucose 6- phosphate, the substrate for step 2 of glycolysis, by a five-step pathway that begins with galactokinase

Glucagon is released when...

Glucagon is released when...blood glucose concentration drops.

What is the role of Glucagon?

Glucagon stimulates the breakdown of glycogen in the liver and release of glucose. Proteins and lipids are also broken down so that amino acids from proteins and glycerol from lipids can be converted to glucose in the liver by the gluconeogenesis pathway.

Gluconeogeneis:

Gluconeogeneis: The synthesis (creation) of Glucose

What is the preferred fuel for brain, muscle during activity, and red blood cells?

Glucose A stable blood glucose concentration is vital for proper functioning of the body.

What is the preferred fuel for the brain, working muscle cells, and red blood cells?

Glucose Glucose is the major fuel for your body. It is the preferred fuel for the brain, working muscle cells, and red blood cells.

What are the 4 other major monosaccharides from digestion?

Glucose (duh)—fructose, galactose, and mannose—eventually join the glycolysis pathway.

How many pathways are involved in the synthesis (creation) of Glucose from noncarbohydrates?

Glucose is so important for energy production that there are two pathways involved in the synthesis (creation) of glucose from noncarbohydrates. Gluconeogeneis The Cori cycle

____________ , the storage form of glucose in animals, is a branched polymer of glucose.

Glycogen, the storage form of glucose in animals, is a branched polymer of glucose.

Glycogenesis:

Glycogenesis = Glycogen synthesis (creation of Glycogen) Occurs when glucose concentrations are high. It begins with glucose 6-phosphate and occurs via three steps.

Glycolysis is a universal pathway to get _________from _________.

Glycolysis is a universal pathway to get energy from glucose.

Does the Absence of Food create an Increase or Decline in Blood Glucose Concentration?

In the Absence of food, there is a gradual decline in Blood Glucose Concentration.

Which Step in glycolysis is a Dehydration reaction?

Step 9

Hypoglycemia causes....

Hypoglycemia causes weakness, sweating, and rapid heartbeat, and in severe cases, low glucose in brain cells causes mental confusion, convulsions, coma, and eventually death. It causes increased urine flow as the normal osmolarity balance of fluids within the kidney is disturbed. Prolonged hyperglycemia can cause low blood pressure, coma, and death.

In Aerobic conditions, pyruvate is converted to __________.

In Aerobic (normal oxygen-rich) conditions, pyruvate is converted to Acetyl-CoA

Steps of Gluconeogenesis

In Step 1 of gluconeogenesis, pyruvate is converted to oxaloacetate by pyruvate carboxylase in an energy-expensive reaction that bypasses the last, irreversible step in glycolysis. Next, oxaloacetate is reduced to malate, transported into the cytosol, and reconverted to oxaloacetate In Step 2, phosphoenolpyruvate carboxykinase adds a phosphate group and rearranges oxaloacetate to produce phosphoenolpyruvate. This is the first of three instances that bypass irreversible steps in glycolysis. The next five reactions of the 10-step glycolysis pathway are reversible. They occur in reverse, catalyzed by the same enzymes as in glycolysis. Step 8 is the conversion of fructose 1,6 bisphosphate to fructose 6-phosphate. Fructose 1,6-bisphosphatase removes a phosphate group by hydrolysis in an energetically favorable reaction The next-to-last reaction converts fructose 6-phosphate to glucose 6-phosphate. The final reaction in the pathway is the third bypass of a glycolysis pathway reaction. Glucose 6-phosphatase hydrolyzes glucose 6-phosphate producing glucose and inorganic phosphate.

Anaerobic Reduction to Lactate:

In reduction of pyruvate to lactate, NADH serves as the reducing agent and is reoxidized to NAD+

In Anaerobic conditions, pyruvate is _________________________________.

In the absence of oxygen or anaerobic conditions, pyruvate is reduced to lactate OR converted to ethanol. Yeast converts pyruvate to ethanol under anaerobic conditions.

Insulin is released when...

Insulin is released when... blood glucose concentration rises.

What is the role of Insulin?

Insulin's role is to decrease blood glucose concentrations by signaling cells to take in glucose. Insulin sends GLUT4 to cell surface (GLUT4 and GLUT1 absorb glucose)

Lactate absorbed from the blood is converted to _________ , the reactant for the first step of gluconeogenesis.

Lactate absorbed from the blood is converted to pyruvate, the reactant for the first step of gluconeogenesis.

Lactate is a product of ____________ in red blood cells and in muscle cells during vigorous muscle activity

Lactate is a product of glycolysis in red blood cells and in muscle cells during vigorous muscle activity

Mannose

Mannose is a product of the hydrolysis of plant polysaccharides other than starch. It is converted by hexokinase and a multistep, enzyme-catalyzed rearrangement to fructose 6- phosphate as the substrate for step 3

Alcoholic Fermentation:

Microorganisms have evolved numerous anaerobic strategies for energy production, generally known as fermentation. When pyruvate undergoes fermentation by yeast, it is converted into ethanol plus carbon dioxide.

In Aerobic Conditions...

NAD+ ---> NADH/H+ Reduction

In Anaerobic Conditions...

NADH/H+ ---> NAD+ Oxidation

Can Phosphorylated molecules cross a cell membrane?

No, Phosphorylated molecules cannot cross a cell membrane. Example of this: Once Glucose enters a cell it is turned to Glucose 6-phosphate and then cannot cross the cell membrane. Keep in mind that it has other pathways though.

Normal blood glucose concentration ranges from __ to ___ mg/dL.

Normal blood glucose concentration ranges from 65 to 100 mg/dL.

Overall _____ molecules of ATP are produced from one glucose molecule during the Glycolytic pathway.

Overall 2 molecules of ATP are produced from one glucose molecule during the Glycolytic pathway.

What is the Oxidation Reaction Phase of Glycolysis?

Oxidation reaction: ATP neither consumed nor produced Note - formation of C-O-P bonds

What is the only pathway driven by molecular oxygen?

Oxidative phosphorylation

Identify each step in glycolysis that is a phosphorylation reaction:

Steps 1, 3, 7

What is the Preparatory Phase of Glycolysis?

Preparatory phase: Cuts glucose into TWO three-carbon chunks. Two ATP consumed - both times one end of the original 6-carbon molecule is phosphorylated.

What is the number of ATP molecules consumed and produced during each part of the glycolysis pathways to get the end (net result) of 2 molecules of ATP produced?

Preparatory phase: 2 ATP consumed Oxidation reaction: ATP neither consumed nor produced... ATP production phase:

Aerobic Oxidation of Pyruvate to AcetylCoA:

Pyruvate moves across the outer mitochondrial membrane, then must be carried by a transporter protein across the inner mitochondrial membrane. Once within the mitochondrial matrix, pyruvate encounters the pyruvate dehydrogenase complex, a large multienzyme complex that catalyzes the conversion of pyruvate to acetyl-CoA.

Identify each step in glycolysis that is an isomerization reaction:

Steps 2, 5, and 8

Steps 4 and 5 of Glycolysis:

Steps 4 and 5 of Glycolysis: Cleavage and Isomerization Step 4 converts the 6-carbon bisphosphate from step 3 into two 3-carbon monophosphates, an aldose phosphate, and one ketose phosphate. Aldolase catalyzes the breakage of the bond between carbons 3 and 4 in fructose 1,6-bisphosphate, and a C=O group is formed.

Step 1 of Glycolysis:

Step 1 of Glycolysis: Phosphorylation Glucose is carried in the bloodstream to cells, where it is transported across the cell membrane into the cytosol. As soon as it enters the cell, glucose is phosphorylated, which requires an energy investment from ATP. These phosphorylated glucose molecules are then trapped within the cells (bc phosphates are charged and charged things cannot cross cell membranes unaided.) The glucose 6-phosphate, is an allosteric inhibitor for the enzyme for this step (hexokinase)

Which Step in glycolysis is a Phosphate Transfer Reaction?

Step 10

Step 2 of Glycolysis:

Step 2 of Glycolysis: The Isomerization of Glucose 6-Phosphate to Fructose 6-Phosphate The enzyme (glucose 6-phosphate isomerase) converts glucose 6-phosphate (an aldohexose) to fructose 6-phosphate (a ketohexose). Isomerase converts (glucose 6-phosphate) --> ( fructose 6-phosphate) This conversion prepares the molecule for addition of another phosphoryl group in the next step.

Step 3 of Glycolysis:

Step 3 of Glycolysis: A Second Energy Investment as Fructose 6-Phosphate Is Converted to Fructose 1,6-Bisphosphate by Reaction with ATP When the cell is short of energy, ADP and AMP concentrations build up and activate the step 3 enzyme, phosphofructokinase. When energy is in good supply, ATP and citrate build up and allosterically inhibit this enzyme.

Which step in glycolysis is a Cleavage reaction?

Step 4

Which step in glycolysis is an Oxidation reaction?

Step 6

Steps 6-7 of Glycolysis:

Steps 6-7 of Glycolysis: Energy Generation Step 6 is the oxidation of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate by glyceraldehyde 3-phosphate dehydrogenase. Some of the energy from the exergonic oxidation is captured in NADH. Step 7 generates the first ATP of glycolysis by transferring a phosphate group from 1,3-bisphosphoglycerate to ADP.

Steps 8-10 of Glycolysis:

Steps 8-10 of Glycolysis: Energy Generation Steps 8 and 9 are an isomerization of 3-phosphoglycerate to 2-phosphoglycerate catalyzed by phosphoglycerate mutase (step 8) followed by dehydration of 2-phosphoglycerate by enolase (step 9). This generates phosphoenolpyruvate, the second energy providing phosphate of glycolysis. Step 10 is a highly exergonic, irreversible transfer of a phosphate group to ADP catalyzed by pyruvate kinase.

The Cori cycle

The Cori cycle converts lactate into pyruvate, the substrate for gluconeogenesis, a pathway that makes glucose from noncarbohydrate molecules beginning with pyruvate.

The absence of food results in the increased release of ________ from __________.

The absence of food results in the increased release of Glucose from Glycogen.

Glycolysis:

The biochemical pathway that breaks down a molecule of glucose into two molecules of pyruvate plus energy (two ATP molecules and two NADH molecules)

What two hormones does the body use to regulate blood glucose levels?

The body uses the hormones Insulin and Glucagon to control blood glucose levels along with mechanisms to store and release glucose as needed.

The brain and other tissues are able to switch over to producing up to 50% of their ATP from catabolism of _______________ instead of glucose.

The brain and other tissues are able to switch over to producing up to 50% of their ATP from catabolism of ketone bodies instead of glucose.

The conversion of glucose to pyruvate is a __________________ in most living systems.

The conversion of glucose to pyruvate is a central metabolic pathway in most living systems.

When glucose enters a cell, it is converted to glucose 6-phosphate. This "Costs" ______ ATP.

When glucose enters a cell, it is converted to glucose 6-phosphate. This "Costs" 1 ATP

What is the ATP production Phase of Glycolysis?

The second half of glycolysis: return on investment: (Steps 6 through 10) The second half of glycolysis involves phosphorylation without ATP investment (step 6) and produces two NADH and four ATP molecules per glucose. #6 step uses electron carrier NAD+, to oxidize the sugar (glyceraldehyde-3-phosphate) which then produces NADH #7 step 1,3-bisphosphoglycerate donates a high-energy phosphate to ADP, forming one molecule of ATP. Then 3-bisphosphoglycerate is oxidized, and 3-phosphoglycerate is formed. #8 A carbonyl group on the 1,3-bisphosphoglycerate is oxidized to a carboxyl group, and 3-phosphoglycerate is formed. #9 The enzyme Enolase causes 2-phosphoglycerate to lose water from its structure; this is a dehydration reaction, resulting in the formation of a double bond that increases the potential energy in the remaining phosphate bond and produces phosphoenolpyruvate (PEP). #10 step is catalyzed by the enzyme pyruvate kinase (reverse reaction of pyruvate's conversion into PEP) and results in the production of a second ATP molecule by substrate-level phosphorylation and the compound pyruvic acid (or its salt form, pyruvate).

The total energy output from oxidation of glucose is the combined result of how many pathways?

The total energy output from oxidation of glucose is the combined result of 4 pathways.

When energy is needed, glucose 6-phosphate goes through _________ to ___________and then _____________, which enters the _______________.

When energy is needed, glucose 6-phosphate goes through Glycolysis to Pyruvate and then to Acetyl-Coenzyme A, which enters the Citric Acid Cycle.

When glucose enters a cell, what it is converted to?

When glucose enters a cell, it is converted to Glucose 6-phosphate. This "Costs" one ATP This change results in the glucose (now glucose 6-phosphate) not being able to pass the cell membrane, thus trapping the glucose within the cell. But there are several other pathways for glucose 6-phosphate.

Does gluconeogenesis uses the same enzymes as those used in glycolysis?

Yes