BI108 Quiz 2

What is electrical energy?

The movement of charged particles (i.e. electrons)

What is thermal energy?

The motion of ions/molecules measured as temperature

What is potential energy?

Energy of position (i.e. position of electrons in bonds)

What is free energy?

The total energy available to do work, combination of entropy, thermal energy, and potential energy.

How is change in free energy expressed?

ΔG → positive = endergonic + non-spontaneous, negative = exergonic and spontaneous

What is the structure and function of ATP?

Structure: 3 phosphate groups attached to ribose (5-C sugar) and adenine (nitrogenous base) with 4 closely-packed negative charges making high potential energy

Function: source of energy for cells and provide energy for non-spontaneous reactions

Reactions: What is phosphorylation?

A phosphate group ion is transferred to another molecule (i.e. ATP - ADP)

Reactions: What is an endergonic reaction?

results in the increase of free energy

Reactions: What is an exergonic reaction?

results in the decrease of free energy (spontaneous)

Reactions: Why are exergonic reactions not necessarily fast?

Due to:

• Spatial orientation: it is unlikely for reactants to bump into each other randomly, much less at the right orientation

• Activation energy: in the transition state (between breaking and making bonds), reactants are less stable than before the reaction started, meaning free energy/activation energy spikes

Reactions: What are anabolic reactions?

polymers made from monomers where energy input is required (endergonic and nonspontaneous)

Reactions: What are catabolic reactions?

Monomers made from polymers where energy is outputted (exergonic and spontaneous)

Reactions: What is a redox reaction?

They change electron position in a covalent bond and drive ATP production → 2 parts:

Oxidation: loss of electrons (spontaneous and exergonic)

Reduction: gain of electrons (non-spontaneous and endergonic)

What do enzymes do?

They act as catalysts to one specific reaction by increasing the probability that reactants line up and lower activation energies

What is the structure and function of the enzyme-substrate complex?

Structure: held together by hydrogen bonds, electrical attraction, temporary covalent bonds, and Van der Waals forces

Function: a substrate binds to the active site of an enzyme causing a conformational change

What are the 3 types of enzyme regulation?

Active site inhibition: inhibitor binds to active site preventing substrates from binding to active site (competitive inhibition)

Allosteric inhibition: inhibitor binds elsewhere on enzyme to change the shape of the active site so substrate cannot bind

Allosteric activation: activator binds elsewhere on enzyme to change the shape of the active site to allow substrate to bind

What are kinases?

Enzymes that catalyze phosphorylation

What are the 5 steps of cellular respiration?

Glycolysis → pyruvate processing → citric acid cycle → ETC → ATP synthase

Cellular respiration: What happens during glycolysis?

A sequence of enzyme-catalyzed reactions where glucose breaks into 2 3-carbon molecules (pyruvate). Steps 1-5 require ATP, while steps 6-10 yield NADH and ATP

Cellular respiration: What happens during pyruvate processing?

In a single, multi-unit enzyme complex, pyruvate is used to create acetyl CoA using acetyl coenzyme A, oxidizing 2 carbons in glucose to CO2

Cellular respiration: What happens during the citric acid cycle?

A sequence of 9 enzyme-catalyzed reactions where acetyl CoA oxidizes glucose

Cellular respiration: What happens in the ETC?

NADL and FADH2 carry electrons from citric acid cycle:

1. NADH goes to complex 1 triggering redox reactions in complexes 2 and 4

2. FADH2 goes to complex 2 and transfers electrons to trigger redox reactions in complexes 2, 3, and 4

3. NADH, FADH2, and Q bring electrons to a series of redox reactions releasing energy allowing protons to move

4. Complex 4 makes O2 act as an electron acceptor → O-O double bond breaks, electrons are added, protons follow, forming H2O

Cellular respiration: What does ATP synthase do?

1. protons enteer and flow through F0 subunit, making it spin

2. axle of rotor spins

3. twisting of axle makes F1 subunit change shape to catalyze the addition of a phosphate group for ADP→ATP

Cellular respiration: What are the electron carriers?

NADL, FADH2, and Q

What is metabolism and what are the principles?

It describes all chemical reactions occurring in a biological system at a given time, the principles are:

1. complex pathways happen over multiple reactions

2. each reaction is catalyzed by an enzyme

3. key enzymes are regulated to alter rate of reaction

4. many pathways are similar in all organisms

5. in eukaryotes, pathways occur in different organelles