Cellular Respiration and Metabolic Pathways

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Questions and Answers

What primarily regulates the rate of cellular respiration during exercise?

Hormonal balance in the blood

Body temperature regulation

Supply and demand of energy (correct)

Dietary intake of carbohydrates

Which enzyme is the main control point for glycolysis?

Hexokinase

Lactate dehydrogenase

Pyruvate kinase

Phosphofructokinase (correct)

How does feedback inhibition function during aerobic respiration?

By enhancing enzyme activity when product levels are high

By prolonging the reaction times of all enzymes involved

By making products act as non-competitive inhibitors on early enzymes (correct)

By increasing oxygen consumption whenever ATP levels decrease

What effect does a higher concentration of nutrients have on reaction rates?

Increases the reaction rate Signup and view all the answers

Which of the following statements about pyruvate dehydrogenase is true?

It is inhibited by NADH Signup and view all the answers

Which macromolecule can enter glycolysis after being broken down?

Carbohydrates Signup and view all the answers

What is generally measured as an indicator of basal metabolic rate?

Oxygen consumption Signup and view all the answers

Which factor does not directly affect the rate of reaction in metabolic pathways?

Dietary habits Signup and view all the answers

What is the process called when the amino group is removed from an amino acid?

Deamination Signup and view all the answers

Where does the deamination process primarily occur in the body?

Liver Signup and view all the answers

What is produced from the removal of the amino group during protein catabolism?

Urea Signup and view all the answers

How many Acetyl-CoA molecules can be produced from a 12-carbon fatty acid chain?

6 Signup and view all the answers

What is the first step in lipid catabolism for fat molecules?

β-oxidation Signup and view all the answers

When glycerol is metabolized, what can it eventually convert to in the glycolytic pathway?

Glyceraldehyde 3-Phosphate Signup and view all the answers

During the cleavage of each fatty acid, how many ATP are used?

1 ATP per cleavage Signup and view all the answers

What occurs when an amino group is transferred from one amino acid to another?

Transamination Signup and view all the answers

Study Notes

Regulating Cellular Respiration and Metabolic Pathways

Cellular respiration rate depends on supply and demand
High demand during exercise, low demand when resting
Basal metabolic rate (BMR) measures energy expenditure at rest, usually measured in oxygen consumption
BMR varies with age and sex

Regulation of Aerobic Respiration

Feedback inhibition is a process that allows the cell to control the rate of biochemical reactions
The product of the last reaction in a pathway inhibits the enzyme that catalyzes the first reaction in the pathway
This ensures that enough product is available for each reaction.
Feedback Inhibition of Enzymes in Aerobic Respiration
Many enzymes in glycolysis and the Krebs cycle are controlled by feedback inhibition of ATP and NADH
Phosphofructokinase (PFK) is the main control point in glycolysis
ATP inhibits PFK, signifying that when there is enough ATP, it binds to an allosteric site on the enzyme
Citrate inhibits PFK, Pyruate is not converted to acetyl-CoA until there's limited citrate
Feedback Inhibition of Pyruvate Dehydrogenase
Pyruvate dehydrogenase is inhibited by NADH, slowing the conversion of pyruvate to Acetyl-CoA, and CO2.

Other Factors Affecting Rate of Reaction

Temperature: Higher temperatures lead to faster reactions.
Nutrient concentration: Higher concentrations result in faster reactions.
Availability of oxygen: Critical for cellular respiration efficiency and reaction rate.

Interconnections of Metabolic Pathways

Mitochondria harvests energy from one glucose molecule
Carbohydrates that can be converted to glucose enter glycolysis
Other macromolecules (proteins, lipids) can also be used for energy

Protein Catabolism

Proteins are broken down into amino acids
Amino acids can be converted to intermediates of glycolysis or the Krebs cycle before being used.
Deamination removes amino groups from amino acids.
Ammonia is created during deamination which can then be converted to urea, excreted by the kidneys
Transamination transfers amine groups to other amino acids

Lipid Catabolism

Fat molecules are broken down into glycerol and fatty acids
Glycerol can be converted to a glucose molecule via gluconeogenesis
Glycerol is converted into Glyceraldehyde 3-Phosphate, which makes pyruvate
Fatty acids undergo beta oxidation to form Acetyl-CoA
Each 2-carbon unit becomes an acetyl Co-A to enter the Krebs Cycle
12 carbon fatty acid chain = 6 Acetyl-CoA molecules

ATP Production

Each cleavage of a fatty acid uses 1 ATP and produces 1 NADH and 1 FADH2
The number of ATP produced per fatty acid cleavage needs to be determined.
18 carbon fatty acid yields 9 Acetyl CoA's.
Through the Krebs Cycle and electron transport chain, these 9 Acetyl CoAs will contribute to 27 NADH, 9 FADH2, and 9 ATP.

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Description

Explore the regulation of cellular respiration and metabolic pathways, including the impact of exercise and rest on metabolic rates. Understand how feedback inhibition plays a critical role in aerobic respiration and the regulation of key enzymes like phosphofructokinase (PFK).