Bac-T Exam 2

What is matter?

Matter is anything that takes up space or has mass, and it cannot be created or destroyed, just rearranged.

What is the capacity to do work or supply heat?

Energy

What is the total amount of energy available to do work called?

Free energy (G)

What work do cells do?

They build macromolecules (ex: DNA, RNA, proteins) and they perform active transport (ex: making concentration gradients)

What is stored energy in chemical bonds or in electrochemical gradients?

Potential energy

What is energy in motion called? Ex: electromagnetic energy (light) or thermal energy

Kinetic energy

What is the first law of thermodynamics?

Energy cannot be created nor destroyed, but it can be transformed.

What is the second law of thermodynamics?

The amount of disorder (entropy) in the universe tends to increase spontaneously.

A reaction that releases energy into the environment, is spontaneous, and has a ΔG < 0.

Exergonic Reaction

A reaction that uses or absorbs energy from the environment, is nonspontaneous, and has a ΔG > 0.

Endergonic Reaction

Contains crammed phosphate groups which give it high amounts of energy; most cellular reactions use this.

ATP hydrolysis

Reactions that add Pi to ADP are…

Exergonic

Reactions that take Pi from ATP are…

Endergonic

Building large biomolecules (anabolic) where the desired products have more free energy (ΔG) than the reactants are considered…

Endergonic

Breaking down molecules (catabolic) to create products with a lower (ΔG) than the reactants are considered…

Exergonic

Why do cells couple catabolic and anabolic reactions?

Because together the reaction can occur faster and we need a constant energy supply.

_____ is and energy carrier.

ATP

What does phosphorylation do?

Stores energy

What is substrate level phosphorylation?

Moving a phosphate group from organic molecule to another. Ex: glycolysis

What is oxidative phosphorylation?

Adding a phosphate group through redox reactions.

What is photophosphorylation?

Adding a phosphate group using light energy.

_______ can also carry energy.

Electrons

This redox reaction occurs when there’s a LOSS of electrons which lowers the energy.

Oxidation reaction

This redox reaction occurs when there is a GAIN of electrons, which increases the energy and adds a negative charge.

Reduction reaction

Remember OIL RIG

What is activation energy? (Ea)

The energy that reactions require to reach their transition state.

What are the proteins that catalyze reactions that in turn make them happen faster?

Enzymes

How do enzymes speed reactions?

They help reactants arrive in the correct orientation and stabilize the transition state to lower activation energy (Ea).

Enzymes DO NOT affect start/end points and the free energy of the reaction DOES NOT change, only the ________.

Activation energy (Ea)

Enzyme used for hydrolysis (catabolic)

Hydrolase

Enzyme that rearranges atoms within and a molecule. (neither catabolic nor anabolic)

Isomerase

Enzyme that join two or more chemicals together (anabolic)

Ligase or polymerase

Enzyme that splits a chemical into smaller parts without the use of water. (catabolic)

Lyase

Enzyme that transfers electrons or hydrogen atoms from one molecule to another.

Oxidoreductase

Enzyme that moves a functional group from one molecule to another (may be anabolic)

Transferase

Holoenzymes require multiple parts to activate. What are they?

• Apoenzyme: protein component (many enzymes are just protein)

• Inorganic cofactors: inorganic ions ex: Fe, Mg, Cu, Zn

• Coenzymes: organic cofactors ex: CoA in cellular respiration

• Active site: catalyzes the reaction, where the reactants bind

What does enzyme activity depend on?

• Temperature: needs energy for rxn, but too much it will denature

• pH: optimal range for correct folding

• Substrate concentration

The type of inhibition that targets the active site by mimicking the substrate and is concentration dependent.

Competitive inhibition

This regulation occurs when the active site activities when substrates bind to a different site on the enzyme.

Allosteric activation

The type of inhibition that changes the shape of the active site when a substance binds to another site on the enzyme.

Allosteric inhibition

How do enzymes function in metabolic pathways?

Sequential activation and/or feedback inhibition