Integration of Metabolism Unit 1

What is bioenergetics?

The study of how energy is captured, transferred, and used in biological systems.

How is energy captured and utilized in cells?

Energy from nutrients is converted into ATP, which powers cellular work like biosynthesis, transport, and movement.

What is metabolism?

The sum of all chemical reactions in a cell or organism.

How are metabolic pathways organized?

As stepwise, enzyme-regulated reactions that are tightly controlled to maintain balance.

What is regulation of metabolism?

Control of metabolic pathways through enzymes, hormones, and energy availability.

What are catabolic pathways?

Pathways that break down molecules to release energy (ex: glycolysis).

What are anabolic pathways?

Pathways that build complex molecules using energy (ex: protein synthesis).

What are amphibolic pathways?

Pathways that function in both catabolism and anabolism (ex: citric acid cycle).

How do anabolic and catabolic pathways work together?

Catabolism provides energy and building blocks for anabolism.

What is an oxidation–reduction (redox) reaction?

A reaction involving the transfer of electrons.

What is oxidation?

Loss of electrons

What is reduction?

Gain of electrons

Why are redox reactions important in metabolism?

They allow energy transfer and ATP production.

What are the major metabolic fuels?

Carbohydrates, fats, and proteins.

Which macromolecules serve as metabolic fuels?

Carbohydrates (glucose), lipids (fatty acids), and proteins (amino acids).

What is the fed state?

A state where energy comes mainly from dietary glucose.

What is the fasting/starved state?

A state where stored fuels (fat and glycogen) are used for energy.

What is tissue specificity in fuel use?

Different tissues prefer different fuels (e.g., brain prefers glucose)

What is metabolic flexibility?

The ability to switch between fuel sources depending on availability.

What is energy balance?

The relationship between energy intake and energy expenditure.

What is positive energy balance?

Intake > expenditure (weight gain).

What is negative energy balance?

Expenditure > intake (weight loss).

What determines basal metabolic rate (BMR)?

Age, gender, body size, genetics, and hormone levels.

Does daily energy expenditure change with age?

Yes, it generally decreases due to loss of lean muscle mass.

What factors influence food intake?

Hormones, hunger signals, stress, environment, and psychology.

What is the first law of thermodynamics?

Energy cannot be created or destroyed, only transformed.

What is the second law of thermodynamics?

Entropy (disorder) increases in spontaneous processes.

What is an exothermic reaction?

A reaction that releases energy.

What is an endothermic reaction?

A reaction that requires energy input.

What is Gibbs free energy (ΔG)?

The energy available to do work.

When is a reaction spontaneous?

When ΔG is negative.

How do non-spontaneous reactions occur in cells?

Through coupling with ATP hydrolysis.

Why is ATP essential?

It is the primary energy currency of the cell.

How is energy released from ATP?

By breaking the phosphate bond during hydrolysis.

What is the ATP–ADP cycle?

ATP is continuously broken down and regenerated to transfer energy.

What determines amino acid properties?

The chemical nature of the side chain (R group).

How are amino acids grouped?

Nonpolar, polar, charged, acidic, or basic.

What interactions occur between amino acids?

Hydrogen bonds, ionic interactions (salt bridges), and hydrophobic interactions.

What are the four levels of protein structure?

Primary, secondary, tertiary, quaternary.

Why is protein structure important?

Structure determines function.

How can a mutation affect protein function?

By altering amino acid sequence and folding.

What is the primary function of enzymes?

To speed up chemical reactions.

What is an active site?

The region where substrate binds and the reaction occurs.

What is a cofactor?

A non-protein helper required for enzyme activity.

What are the two enzyme-substrate models?

Lock-and-key and induced fit.

How can enzymes be regulated?

By modifying enzyme activity or changing enzyme quantity.

What is the central dogma of biology?

DNA → RNA → Protein.

Where do mutations occur?

At the DNA level.

How can mutations affect metabolism?

By altering enzyme structure and function.

How does sickle cell disease illustrate mutation effects?

A DNA mutation causes an amino acid change, altering protein structure and metabolism.