Chapters 2.3, 2.4, 3.5: Chemical Reactions, Energy, Enzymes and Chapter 5.1–5.4: Cell Metabolism: Aerobic Respiration and Fermentation

What is energy?

The capacity to produce change

What is kinetic energy?

Energy of movement

What is potential energy?

Stored energy

What type of energy is heat?

Kinetic energy

What type of energy is stored in chemical bonds?

Potential energy

What does the First Law of Thermodynamics state?

Energy cannot be created or destroyed only transferred or transformed

In a closed system what happens to total energy?

It remains constant

What does the Second Law of Thermodynamics state?

Energy transfers increase entropy

What is entropy?

A measure of disorder or unusable energy

What happens to entropy during energy transformations?

It increases

Why can reactions that decrease entropy not occur spontaneously?

They require energy input

What is a chemical reaction?

A process where atoms combine or change bonding partners

What are reactants?

The starting molecules in a chemical reaction

What are products?

The molecules produced by a chemical reaction

What is hydrolysis?

A reaction where water breaks bonds and splits molecules

Hydrolysis breaks molecules into what?

Smaller molecules

What is the opposite of hydrolysis?

Condensation

What happens during condensation?

Two molecules combine to form a larger molecule and release water

What is Gibbs free energy (G)?

The energy available to do work in a reaction

What does a negative G value mean?

The reaction releases energy

What type of reaction has a negative G?

Exergonic reaction

What does a positive G value mean?

The reaction requires energy

What type of reaction has a positive G?

Endergonic reaction

In exergonic reactions are reactants higher or lower energy than products?

Higher energy

In endergonic reactions are reactants higher or lower energy than products?

Lower energy

Do exergonic reactions release or require energy?

Release energy

Do endergonic reactions release or require energy?

Require energy

What are catabolic reactions?

Reactions that break large molecules into smaller molecules

Do catabolic reactions release or require energy?

Release energy

What are anabolic reactions?

Reactions that build large molecules from smaller molecules

Do anabolic reactions release or require energy?

Require energy

What is activation energy?

The energy needed to start a chemical reaction

Do both endergonic and exergonic reactions require activation energy?

Yes

Why must activation energy be supplied?

To break existing bonds

What is reaction rate?

The speed at which products are formed

What three factors affect reaction rate?

Activation energy concentration and temperature

How does higher temperature affect reactions?

Increases molecular collisions and reaction rate

How does higher concentration affect reactions?

Increases collisions between molecules

What is chemical equilibrium?

When forward and reverse reactions occur at the same rate

At equilibrium do reactant concentrations change?

No

What are enzymes?

Proteins that speed up chemical reactions

What is catalysis?

Speeding up a chemical reaction

Do enzymes get consumed in reactions?

No

Can enzymes be reused?

Yes

What is a substrate?

The reactant molecule an enzyme acts on

Where does a substrate bind on an enzyme?

Active site

What is an enzyme substrate complex?

The temporary complex formed when an enzyme binds a substrate

Why are enzymes highly specific?

Their active sites have a specific 3D shape

What happens to the enzyme after products are released?

It remains unchanged and can be reused

What is induced fit?

The change in shape of the enzyme active site when the substrate binds

What is denaturation?

Loss of protein structure and function

What can cause denaturation?

Heat pH changes or chemicals

What is a ligand?

A chemical signal that binds to a receptor protein

What happens to a receptor when a ligand binds?

It undergoes a conformational change

What is binding affinity?

How strongly a ligand binds to a protein

What is a cofactor?

A non protein molecule that helps an enzyme function

What is a prosthetic group?

A tightly bound cofactor

What is a coenzyme?

A loosely bound organic cofactor

What is proteolysis?

Cleaving part of a protein to activate or deactivate it

What is phosphorylation?

Adding a phosphate group to a protein

What enzyme adds phosphate groups?

Kinase

What enzyme removes phosphate groups?

Phosphatase

What are metabolic pathways?

Series of chemical reactions where the product of one reaction becomes the substrate for the next

Are metabolic pathways catalyzed by enzymes?

Yes

Why are metabolic pathways efficient?

They break reactions into many small steps

What is ATP?

The main energy currency of the cell

What does ATP stand for?

Adenosine triphosphate

What does ATP hydrolysis produce?

ADP Pi and energy

What does ADP stand for?

Adenosine diphosphate

What type of reaction releases energy from ATP?

Hydrolysis

What are redox reactions?

Reactions involving transfer of electrons

What is oxidation?

Loss of electrons

What is reduction?

Gain of electrons

Do oxidation and reduction occur together?

Yes

What molecule carries electrons in cells?

NAD

What is the oxidized form of NAD?

NAD+

What is the reduced form of NAD?

NADH

What happens when NAD+ gains electrons?

It becomes NADH

What is cellular respiration?

The process cells use to harvest energy from food molecules

What molecule is broken down in cellular respiration?

Glucose

What is the overall cellular respiration equation?

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

What are the four stages of cellular respiration?

Glycolysis pyruvate oxidation citric acid cycle oxidative phosphorylation

Where does glycolysis occur?

Cytoplasm

What molecule starts glycolysis?

Glucose

How many carbons does glucose have?

6

What are the products of glycolysis?

2 pyruvate 2 NADH and net 2 ATP

What is the net ATP gain of glycolysis?

2 ATP

What two stages occur in glycolysis?

Energy investment and energy harvest

Where does pyruvate oxidation occur?

Mitochondrial matrix

What molecule is produced from pyruvate oxidation?

Acetyl CoA

What gas is released during pyruvate oxidation?

CO2

What cycle follows pyruvate oxidation?

Citric acid cycle

Where does the citric acid cycle occur?

Mitochondrial matrix

What are major products of the citric acid cycle?

NADH FADH2 GTP and CO2

What is another name for the citric acid cycle?

Krebs cycle

What is oxidative phosphorylation?

The stage where most ATP is produced using the electron transport chain and chemiosmosis

What molecule is the final electron acceptor in the electron transport chain?

Oxygen

What is produced when oxygen accepts electrons?

Water

What is chemiosmosis?

The use of a proton gradient to drive ATP synthesis

What enzyme produces ATP during chemiosmosis?

ATP synthase