Metabolism Be sure you can identify or write out a reaction involving oxidation/
ID: 3508601 • Letter: M
Question
Metabolism
Be sure you can identify or write out a reaction involving oxidation/reduction, and whether a reaction might be endergonic or exergonic. What are a couple of ways that you might be able to identify an exergonic reaction?
What are coupled reactions and why is it important physiologically for reactions to be coupled?
Be sure to review how enzymes work with respect to activation energy. How do enzymes behave in reactions? What factors can affect their behavior and how do these factors alter the way the enzyme works? One example might be pH, but physiologically there are others.
What is the difference between allosteric regulation and competitive inhibition? What are some of the enzymes in glycolysis and the TCA cycle that are highly regulated? Why these enzymes and not others in the pathways?
For both glycolysis and the TCA cycle: Be able to identify the inputs, the outcomes, where fuels come from, and their ultimate fates. Be sure you could identify and quantify how many ATPs would be gained if I gave you the compound. For example: try to quantify how many ATPs you would get from a 22-carbon saturated fatty acid. How many ATPs and glucose molecules would you get from the glucogenic amino acid, arginine?
Understand what determines whether glycolysis is aerobic or anaerobic. When would you use each of these two pathways? What happens to lactate when it is produced in anaerobic glycolysis?
What are the major processes that occur in the TCA cycle and the electron transport chain? Where are each of these pathways located in the cell? What regulates the activity of these metabolic pathways?
The electron transport chain is a great example of energy transformation. Be able to articulate where these transformations are occurring and how this is advantageous for the production of ATP. Be able to explain why the electrons carried by NADH + H+ yield a greater number of ATP molecules than those electrons carried by FADH2.
Be able to explain how fats and proteins contribute to metabolism. What is the major role of each of these fuels and when would your body choose to utilize them?
What is the difference between a glucogenic and ketogenic amino acid?
What is gluconeogenesis? What fuels can be used for this pathway? What is the purpose of gluconeogenesis?
Explanation / Answer
Q Be sure you can identify or write out a reaction involving oxidation/reduction, and whether a reaction might be endergonic or exergonic. What are a couple of ways that you might be able to identify an exergonic reaction?
A: Oxidation is gain of oxygen.
Reduction is loss of oxygen.
Because both reduction and oxidation are going on side-by-side, this is known as a redox reaction.
Endergonic and exergonic are two types of chemical reactions or processes in thermochemistry or physical chemistry.
Endergonic reactions:
Exergonic Reactions
B. Endergonic reactions always require energy to start. Some exergonic reactions also have an activation energy, but more energy is released by the reaction than is required to initiate it. For example, it takes energy to start a fire, but once combustion starts, the reaction releases more light and heat than it took to get it started.
By measuring the H of a reaction. If it is lower than zero, than you have a endergonic reaction, and if you have a number higher than zero, you have an exergonic reaction.
What are coupled reactions and why is it important physiologically for reactions to be coupled?
Q. Be sure to review how enzymes work with respect to activation energy. How do enzymes behave in reactions? What factors can affect their behavior and how do these factors alter the way the enzyme works? One example might be pH, but physiologically there are others.
A)The activation energy is the energy required to start a reaction. Enzymes are proteins that bind to a molecule, or substrate, to modify it and lower the energy required to make it react.
B)The Central Role of Enzymes as Biological Catalysts. A fundamental task of proteins is to act as enzymes—catalysts that increase the rate of virtually all the chemical reactions within cells. Although RNAs are capable of catalyzing some reactions, most biological reactions are catalyzed by proteins.
C)Various factors affecting enzymes are: (1) Concentration of Enzyme (2) Concentration of Substrate (3) Effect of Temperature (4) Effect of pH (5) Effect of Product Concentration and (6) Effect of Activators.
D)
Factor # 1. Concentration of Enzyme:
As the concentration of the enzyme is increased, the velocity of the reaction proportionately increases. In fact, this property of enzyme is made use in determining the activities of serum enzymes for diagnosis of diseases.
Factor 2: Concentration of Substrate
Increase in the substrate concentration gradually increases the velocity of enzyme reaction within the limited range of substrate levels.
Factor 3: Effect of Temperature
Velocity of an enzyme reaction increases with increase in temperature up to a maximum and then declines. The optimum temperature for most of the enzymes is between 40°C-45°C.
Factor 4: Effect of pH
Increase in the hydrogen ion concentration (pH) considerably influences the enzyme activity and a bell-shaped curve is normally obtained. Each enzyme has an optimum pH at which the velocity is maximum. Most of the enzymes of higher organisms show optimum activity around neutral pH (6-8)
Factor 5: Effect of Product Concentration
The accumulation of reaction products generally decreases the enzyme velocity
Factor 6: Effect of Activators.
Some of the enzymes require certain inorganic metallic cations like Mg2+, Mn2+, Zn2+, Ca2+, Co2+, Cu2+, Na+, K+ etc. for their optimum activity. Rarely, anions are also needed for enzyme activity e.g. chloride ion (CI–) for amylase.
Q. What is the difference between allosteric regulation and competitive inhibition?
Competitive Inhibition:
1. The inhibitor binds to the active site of enzyme.
2. It does not change conformation of enzyme.
3. The active Site is swamped by inhibitor.
4. The inhibitor resembles the substrate in its broad structure.
5. The inhibitor is not connected by metabolic pathway catalysed by the enzyme.
6. It does not have a regulatory function.
Allosteric Inhibition:
The inhibitor attaches to an area other than the active site.
2. The conformation of an enzyme is changed.
3. The conformation of the active site is changed so that substrate cannot combine with it.
4. The inhibitor has no structural similarity with the substrate.
5. Inhibitor is a product or intermediate of the metabolic pathway connected with that enzyme.
6. Allosteric inhibition has a regulatory function as it stops the excess formation of a product.
Q. Be sure you could identify and quantify how many ATPs would be gained if I gave you the compound. For example: try to quantify how many ATPs you would get from a 22-carbon saturated fatty acid.
A Step 1.- Number of Carbons/2 = Number of Acetyl CoA formed.
Step 2.- Number of rounds in the Beta-oxidation necessary for converting the whole fatty acid to Acetyl Co A units: Number of Acetyl CoA minus 1 [(n/2)-1]
Step 3 If you consider that each NADH yields 2.5 ATP and each FADH2 yields 1.5 ATP then multiply the number of rounds times 4 and multiply the number of Acetyl CoA times 1o
Step 4.- Take two ATP that was used for the activation of the Fatty Acid
Fatty acid with 22 Carbons
Step 1: 22/2 = 11 Acetyl CoA
Step 2: 11-1 = 10 rounds
Step 3: (10 x 4) + (11 x10)
Step 4 = -2
Total: 148 ATP
Q The electron transport chain is a great example of energy transformation. Be able to articulate where these transformations are occurring and how this is advantageous for the production of ATP. Be able to explain why the electrons carried by NADH + H+ yield a greater number of ATP molecules than those electrons carried by FADH2.
Q Be able to explain how fats and proteins contribute to metabolism. What is the major role of each of these fuels and when would your body choose to utilize them?
Fat metabolism:
Fatty acids come from the diet, adipocytes (fat cells), carbohydrate, and some amino acids. After digestion, most of the fats are carried in the blood as chylomicrons. The main pathways of lipid metabolism are lipolysis, beta oxidation, ketosis, and lipogenesis.
Lipolysis (fat breakdown) and beta-oxidation occur in the mitochondria. It is a cyclical process in which two carbons are removed from the fatty acid per cycle in the form of acetyl CoA, which proceeds through the Krebs cycle to produce ATP, CO2, and water.
Ketosis occurs when the rate of formation of ketones by the liver is greater than the ability of tissues to oxidize them. It occurs during prolonged starvation and when large amounts of fat are eaten in the absence of carbohydrate.
Protein metabolism:
Digestion breaks protein down to amino acids. If amino acids are in excess of the body’s biological requirements, they are metabolized to glycogen or fat and subsequently used for energy metabolism. If amino acids are to be used for energy their carbon skeletons are converted to acetyl CoA, which enters the Krebs cycle for oxidation, producing ATP. The final products of protein catabolism include carbon dioxide, water, ATP, urea, and ammonia.
ROLE of Proteins:
Proteins are often called the body’s building blocks. They are used to build and repair tissues. They help you fight infection. Your body uses extra protein for energy
Role of fat: Fats also give you energy and help you feel satisfied after eating
Q What is the difference between a glucogenic and ketogenic amino acid?
Amino acids can be classified into three groups based on the catabolism. They are Glucogenic amino acids, Ketogenic amino acids and mixed amino acids (both Glucogenic and Ketogenic). The main difference between glucogenic amino acids and ketogenic amino acids is that
Q What is gluconeogenesis? What fuels can be used for this pathway? What is the purpose of gluconeogenesis?
Gluconeogenesis is a metabolic pathway that leads to the synthesis of glucose from pyruvate and other non-carbohydrate precursors, even in non-photosynthetic organisms.
Fuels used for this pathway
The precursors of gluconeogenesis are lactate, glycerol, amino acids, and with propionate making a minor contribution. The gluconeogenesis pathway consumes ATP, which is derived primarily from the oxidation of fatty acids. The pathway uses several enzymes of the glycolysis with the exception of enzymes of the irreversible steps namely pyruvate kinase, 6-phosphofructokinase, and hexokinase.
Importance of gluconeogenesis
For eg. After about 18 hours of fasting or during intense and prolonged exercise, glycogen stores are depleted and may become insufficient. At that point, if no carbohydrates are ingested, gluconeogenesis becomes important
The excretion of pyruvate would lead to the loss of the ability to produce ATP through aerobic respiration, i.e. more than 10 molecules of ATP for each molecule of pyruvate oxidized
Q The electron transport chain is a great example of energy transformation. Be ble to articulate where these transformations are occurring and how this is advantageous for the production of ATP. Be able to explain why the electrons carried by NADH + H+ yield a greater number of ATP molecules than those electrons carried by FADH2.
Q Be able to explain how fats and proteins contribute to metabolism. What is the major role of each of these fuels and when would your body choose to utilize them?
Fat metabolism:
Fatty acids come from the diet, adipocytes (fat cells), carbohydrate, and some amino acids. After digestion, most of the fats are carried in the blood as chylomicrons. The main pathways of lipid metabolism are lipolysis, betaoxidation, ketosis, and lipogenesis.
Lipolysis (fat breakdown) and beta-oxidation occurs in the mitochondria. It is a cyclical process in which two carbons are removed from the fatty acid per cycle in the form of acetyl CoA, which proceeds through the Krebs cycle to produce ATP, CO2, and water.
Ketosis occurs when the rate of formation of ketones by the liver is greater than the ability of tissues to oxidize them. It occurs during prolonged starvation and when large amounts of fat are eaten in the absence of carbohydrate.
Protein metabolism:
Digestion breaks protein down to amino acids. If amino acids are in excess of the body’s biological requirements, they are metabolized to glycogen or fat and subsequently used for energy metabolism. If amino acids are to be used for energy their carbon skeletons are converted to acetyl CoA, which enters the Krebs cycle for oxidation, producing ATP. The final products of protein catabolism include carbon dioxide, water, ATP, urea, and ammonia.
ROLE of Proteins:
Proteins are often called the body’s building blocks. They are used to build and repair tissues. They help you fight infection. Your body uses extra protein for energy
Role of fat: Fats also give you energy and help you feel satisfied after eating
Q What is the difference between a glucogenic and ketogenic amino acid?
Amino acids can be classified into three groups based on the catabolism. They are Glucogenic amino acids, Ketogenic amino acids and mixed amino acids (both Glucogenic and Ketogenic). The main difference between glucogenic amino acids and ketogenic amino acids is that
Q What is gluconeogenesis? What fuels can be used for this pathway? What is the purpose of gluconeogenesis?
Gluconeogenesis is a metabolic pathway that leads to the synthesis of glucose from pyruvate and other non-carbohydrate precursors, even in non-photosynthetic organisms.
Fuels used for this pathway
The precursors of gluconeogenesis are lactate, glycerol, amino acids, and with propionate making a minor contribution. The gluconeogenesis pathway consumes ATP, which is derived primarily from the oxidation of fatty acids. The pathway uses several enzymes of the glycolysis with the exception of enzymes of the irreversible steps namely pyruvate kinase, 6-phosphofructokinase, and hexokinase.
Importance of gluconeogenesis
For eg. After about 18 hours of fasting or during intense and prolonged exercise, glycogen stores are depleted and may become insufficient. At that point, if no carbohydrates are ingested, gluconeogenesis becomes important
The excretion of pyruvate would lead to the loss of the ability to produce ATP through aerobic respiration, i.e. more than 10 molecules of ATP for each molecule of pyruvate oxidizedv
Q The electron transport chain is a great example of energy transformation. Be ble to articulate where these transformations are occurring and how this is advantageous for the production of ATP. Be able to explain why the electrons carried by NADH + H+ yield a greater number of ATP molecules than those electrons carried by FADH2.
Q Be able to explain how fats and proteins contribute to metabolism. What is the major role of each of these fuels and when would your body choose to utilize them?
Fat metabolism:
Fatty acids come from the diet, adipocytes (fat cells), carbohydrate, and some amino acids. After digestion, most of the fats are carried in the blood as chylomicrons. The main pathways of lipid metabolism are lipolysis, betaoxidation, ketosis, and lipogenesis.
Lipolysis (fat breakdown) and beta-oxidation occurs in the mitochondria. It is a cyclical process in which two carbons are removed from the fatty acid per cycle in the form of acetyl CoA, which proceeds through the Krebs cycle to produce ATP, CO2, and water.
Ketosis occurs when the rate of formation of ketones by the liver is greater than the ability of tissues to oxidize them. It occurs during prolonged starvation and when large amounts of fat are eaten in the absence of carbohydrate.
Protein metabolism:
Digestion breaks protein down to amino acids. If amino acids are in excess of the body’s biological requirements, they are metabolized to glycogen or fat and subsequently used for energy metabolism. If amino acids are to be used for energy their carbon skeletons are converted to acetyl CoA, which enters the Krebs cycle for oxidation, producing ATP. The final products of protein catabolism include carbon dioxide, water, ATP, urea, and ammonia.
ROLE of Proteins:
Proteins are often called the body’s building blocks. They are used to build and repair tissues. They help you fight infection. Your body uses extra protein for energy
Role of fat: Fats also give you energy and help you feel satisfied after eating
Q What is the difference between a glucogenic and ketogenic amino acid?
Amino acids can be classified into three groups based on the catabolism. They are Glucogenic amino acids, Ketogenic amino acids and mixed amino acids (both Glucogenic and Ketogenic). The main difference between glucogenic amino acids and ketogenic amino acids is that
Q What is gluconeogenesis? What fuels can be used for this pathway? What is the purpose of gluconeogenesis?
Gluconeogenesis is a metabolic pathway that leads to the synthesis of glucose from pyruvate and other non-carbohydrate precursors, even in non-photosynthetic organisms.
Fuels used for this pathway
The precursors of gluconeogenesis are lactate, glycerol, amino acids, and with propionate making a minor contribution. The gluconeogenesis pathway consumes ATP, which is derived primarily from the oxidation of fatty acids. The pathway uses several enzymes of the glycolysis with the exception of enzymes of the irreversible steps namely pyruvate kinase, 6-phosphofructokinase, and hexokinase.
Importance of gluconeogenesis
For eg. After about 18 hours of fasting or during intense and prolonged exercise, glycogen stores are depleted and may become insufficient. At that point, if no carbohydrates are ingested, gluconeogenesis becomes important
The excretion of pyruvate would lead to the loss of the ability to produce ATP through aerobic respiration, i.e. more than 10 molecules of ATP for each molecule of pyruvate oxidized
- A chemical reaction having a common intermediate in which energy is transfered from one side of the reaction to the other.
Examples:
1. The formation of ATP is endergonic and is coupled to the dissipation of a proton gradient.
2. ATP + glucose -> ADP + glucose-1-phosphate and glucose-1-phosphate + fructose -> sucrose + phosphate - a molecule of sucrose is synthesized from glucose and fructose at the expense of the energy stored in ATP and transferred by glucose-1-phosphate - In a coupled reaction energy required by 1 process is supplied by another process, thus preventing the application of extra energy from outside and allowing the reaction to occur on its own.