Lecture 8: Biochemistry and Energy Principles in Cell Metabolism

What is the overarching concept of energy use in organisms?

Organisms use energy for cellular processes, acquired from molecular bonds.

What does the 1st Law of Thermodynamics state?

Energy is neither created nor destroyed.

What does the 2nd Law of Thermodynamics state?

When energy is converted from one form to another, some energy becomes unavailable to do work.

In biochemical reactions, does the reaction increase or decrease potential energy?

decrease potential energy

What is metabolism?

The sum of all catabolic and anabolic pathways in an organism, linked by ATP.

What characterizes spontaneous, exergonic reactions?

They have a negative ΔG and release energy.

What characterizes nonspontaneous, endergonic reactions?

They have a positive ΔG and consume energy.

Potential energy in nonpolar bonds...

longest, weakest bonds -> most potential energy

Potential energy in polar bonds...

shortest, strongest bonds -> less potential energy

What does OIL RIG stand for in redox reactions?

Oxidized is losing electrons; Reduced is gaining electrons.

What is the role of NADH and FADH2 in metabolism?

They are important molecules that are oxidized and reduced continuously.

Reduction of FAD and NAD are _________ and need to be ______.

Endergonic, non-spontaneous

coupled with another reaction

What are coupling reactions?

An exergonic reaction drives an endergonic reaction

What is the ATP cycle?

The continuous recycling of ATP in organisms, coupling exergonic and endergonic reactions.

What happens during ATP hydrolysis?

Energy is released when ATP is hydrolyzed; it is a catabolic reaction.

Phosphate in ATP is removed

exergonic reaction (energy released)

Phosphate is added to ATP

endergonic reaction (energy added)

How do enzymes affect biochemical reactions?

Enzymes reduce the energy investment needed for reactions and increase reaction rates. Also contain binding sites to couple reactions.

What is competitive inhibition in enzyme activity?

A molecule similar to the substrate binds to the enzyme, blocking substrate binding.

What is allosteric regulation?

The binding of a regulatory subunit changes the enzyme's shape, affecting substrate binding.

What is the difference between catabolic and anabolic reactions?

Catabolic reactions break down molecules, while anabolic reactions build molecules.

What is the significance of phosphate bonds in ATP?

They hold a lot of energy, and their hydrolysis releases free energy for cellular work.

What is the function of cofactors in enzyme activity?

Cofactors are nonprotein molecules or inorganic ions that some enzymes require to function.

What is the result of coupling exergonic and endergonic reactions?

An exergonic reaction drives an endergonic reaction, allowing energy transfer.

How does the ATP cycle couple with other reactions in cells?

ATP hydrolysis provides energy for endergonic reactions, while ATP synthesis requires energy.

What is the role of redox reactions in metabolism?

They transfer electrons and protons, playing a crucial role in energy transformations.

What is the importance of understanding enzyme kinetics?

It helps in determining the maximum reaction rate based on substrate concentration.

What is the significance of the ATP molecule in metabolism?

ATP acts as an energy currency, coupling reactions and providing energy for cellular processes.

What happens to potential energy during biochemical reactions?

The products typically have less potential energy than the reactants.

What is the relationship between bond formation and energy?

Breaking unstable bonds requires energy, while forming stable bonds releases energy.

What is the role of enzymes in metabolic pathways?

Each step in a metabolic pathway is catalyzed by a different enzyme, facilitating incremental changes.

What is the difference between hydrolysis and condensation reactions?

Hydrolysis breaks down molecules, while condensation builds them up.

How do metabolic pathways evolve?

They likely evolved backwards, with complex pathways derived from simpler ones.

What is the significance of the ATP synthesis process?

It is an endergonic reaction that requires energy input to form ATP.

What is the function of the electron transport chain in photosynthesis?

It facilitates the transfer of electrons from water, yielding oxygen.

What does the term 'coupling reactions' refer to?

It refers to the process where the energy released from one reaction drives another reaction.