Chapter 4 Part 1: How Cells Obtain Energy

Vocabulary flashcards covering cellular energy, laws of thermodynamics, energy forms, activation energy, enzyme function, inhibition mechanisms, metabolism, and coupled reactions.

Thermodynamics

The study of energy and energy transfer in physical matter, including living organisms.

Energy

The ability to do work or create change.

Open system

A system in which energy and matter can enter or leave.

Closed system

A system in which neither energy nor matter can enter or leave.

First Law of Thermodynamics

The law stating that energy can neither be created nor destroyed, and after an energy transformation, the same amount of energy still exists.

Second Law of Thermodynamics

The law stating that when energy changes form, the amount of useful energy decreases because no energy conversion is $100\%$ efficient and heat is given off as a waste product.

Entropy

The tendency for order to decrease in a system unless energy is applied to counteract it.

Potential energy

Stored energy (such as positional energy or chemical energy stored in molecular bonds like ATP).

Kinetic energy

The energy of movement, which includes light, heat, electricity, and the movement of physical objects.

Activation energy

The energy required to initiate a chemical reaction by forcing the electron shells of atoms together.

• even energy releasing reaction require activation energy

Enzyme

A biological catalyst made of protein.

-specific to substrate

Substrate

A specific molecule or substance acted on by an enzyme.

Active site

A special location on an enzyme specific to its substrate where substrate binding occurs.

Induced fit

The process where an enzyme changes its shape upon binding a substrate to speed up the chemical reaction.

Coenzymes

Molecules that assist catalysts in performing reactions, which often originate from vitamins.

Competitive inhibition

A form of enzyme inhibition where a molecule other than the normal substrate binds to the active site, preventing the normal substrate from binding.

Alcohol dehydrogenase

An enzyme that breaks down methanol into formaldehyde, causing blindness, which can be treated using ethanol as a competitive inhibitor.

Non-competitive inhibition

A form of enzyme inhibition where a molecule binds to a site other than the active site, altering the enzyme so that it is less likely to catalyze a reaction.

Metabolism

The sum of all chemical reactions occurring within a cell.

Metabolic pathway

A linked sequence of chemical reactions in which the product of one reaction becomes the reactant for the next reaction.

Coupled reaction

A process in which the energy released from one chemical reaction is directly used to drive another chemical reaction.

What allows there to be order in living things when they are constantly losing energy as heat?

The sun provides a constant influx of energy.

Molecular movement

Most reactions occur more easily at higher temperature

molecules are always in motion.

Molecules move faster at higher temperature making reactions more likely.

but there is a temperature limit in living things!