Regulating Cellular Respiration Quiz

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Questions and Answers

What primarily regulates the rate of cellular respiration during exercise?

Basal metabolic rate

Supply and demand for energy (correct)

Temperature changes

Availability of lipids

Which enzyme is considered the main control point for glycolysis?

Lactate dehydrogenase

Citrate synthase

Pyruvate kinase

Phosphofructokinase (correct)

What is the role of feedback inhibition in cellular respiration?

To ensure sufficient product availability (correct)

To create ATP from glucose

To increase enzyme activity

To speed up all metabolic pathways

How does the concentration of nutrients affect the rate of reaction in metabolic pathways?

Higher concentration increases reaction speed Signup and view all the answers

What inhibits pyruvate dehydrogenase in the process of aerobic respiration?

NADH Signup and view all the answers

In what manner does temperature affect metabolic reactions?

Higher temperature increases reaction speed Signup and view all the answers

What happens to pyruvate when citrate accumulates in the cell?

Pyruvate conversion to acetyl-CoA is stopped Signup and view all the answers

What occurs when the demand for ATP is low?

Cellular respiration decreases Signup and view all the answers

What process involves the removal of the amino group from an amino acid?

Deamination Signup and view all the answers

In which organ does the process of deamination primarily occur?

Liver Signup and view all the answers

What happens to the ammonia produced from the deamination of amino groups?

Converted into urea Signup and view all the answers

What type of molecule is produced after the hydrolysis of fat molecules?

Glycerol and fatty acids Signup and view all the answers

What is the outcome of 2 glycerol molecules during lipid catabolism?

Form a glucose molecule Signup and view all the answers

How many carbon atoms are removed in each cleavage during fatty acid oxidation?

2 carbon atoms Signup and view all the answers

What is produced alongside each cleavage of a fatty acid during β-oxidation?

1 ATP, 1 NADH, and 1 FADH2 Signup and view all the answers

For a fatty acid chain of 14 carbons, how many acetyl-CoA molecules are generated?

7 Signup and view all the answers

Study Notes

Regulating Cellular Respiration and Metabolic Pathways

Study questions in the text are:
- How does the cell control the rate at which it produces ATP?
- Explain how proteins and lipids can be used for energy.

Regulation of Aerobic Respiration

Rate of cellular respiration depends on:
- Supply and demand
- High demand during exercise
- Low demand when resting
Basal metabolic rate (BMR):
- Amount of energy expended per unit time at rest
- Measured in oxygen consumption
- BMR varies by age and sex (data provided in a chart)

Regulation of Aerobic Catabolic Pathways

Feedback inhibition:
- A process for cells to ensure sufficient product when biochemical reactions occur
- The product of the last reaction inhibits the enzyme catalyzing the first reaction
- Ensures enough product for reactions, reduces unnecessary reactions

Feedback Inhibition of Enzymes in Aerobic Respiration

Many enzymes in glycolysis and Krebs cycle are controlled by feedback inhibition of ATP and NADH
Phosphofructokinase (PFK) is the main control point for glycolysis
ATP inhibits PFK which means sufficient ATP causes inhibition for enough product
Citrate inhibits PFK, causing an accumulation of the substance when conversion to Acetyl-CoA does not occur until sufficient citrate is used by other steps

Pyruvate Dehydrogenase

Inhibited by NADH
Slows down conversion of pyruvate to Acetyl-CoA and CO2

Other Factors Affecting Rate of Reaction

Temperature: Higher temperature leads to faster reactions
Nutrient concentration: Higher concentration leads to faster reactions
Availability of oxygen

Interconnections of Metabolic Pathways

Mitochondria harvest energy from one molecule of glucose
Carbohydrates can be broken down into glucose and enter glycolysis
Other macromolecules (not carbohydrates) also have metabolic pathways

Protein Catabolism

Proteins first broken down to amino acids (hydrolysis)
Before feeding into glycolysis or Krebs cycle, amino groups must be removed
Deamination: removal of the amino group (-NH2) from amino acids
Amino acids can feed into different points of glycolysis or Krebs cycle through different processes
Process occurs in the liver
Amine group converted into ammonia (toxic), then to urea (harmless)
Urea is excreted by kidneys
Amine groups can be transferred to other amino acids (transamination)
Remaining carbon skeletons can feed into different points of glycolysis or Krebs cycle

Lipid Catabolism

Fat molecules broken down into glycerol and fatty acids
Two glycerol molecules combine to form one glucose molecule (gluconeogenesis)
Glycerol is converted into Glyceraldehyde 3-Phosphate (a precursor to pyruvate)
Fatty acids undergo beta-oxidation to become Acetyl-CoA
Carbon atoms are removed 2 at a time
Each 2-carbon unit becomes an acetyl Co-A for use in the Krebs Cycle
Cleavage of fatty acids uses 1 ATP, Produces 1 NADH, 1 FADH2
The amount of ATP yield from a particular fatty acid structure relates to the number of carbons it contains, in multiples of 2

Discussion Question

Calculate ATP production from a 14 Carbon Fatty acid chain

Summary

Carbohydrates, some amino acids, and glycerol enter the metabolic pathway through glycolysis
Pyruvate oxidation leads to the citric acid cycle
Oxidative phosphorylation occurs next to complete the process

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Description

Test your knowledge on how cellular respiration is regulated, including the production of ATP and the roles of proteins and lipids in energy metabolism. This quiz covers key concepts such as supply and demand during exercise, basal metabolic rate, and feedback inhibition in aerobic pathways.