BIOCHEM CH.1

What is an electron?

A negatively charged subatomic particle.

Where are electrons located?

Around the outside, or periphery, of the atom.

What commonly moves during biochemical reactions?

Electrons.

Why are electrons important in biochemical reactions?

Their movement can transfer energy.

What is a proton?

A positively charged subatomic particle.

Where are protons located?

In the nucleus of the atom.

Which is heavier, a proton or an electron?

A proton.

What determines the identity of an element?

The number of protons.

Does the number of protons normally change during a biochemical reaction?

No.

What would happen if the number of protons changed?

The atom would become a different element.

What is a neutral hydrogen atom made of?

One proton and one electron.

What is a hydrogen ion?

A hydrogen atom that has lost its electron.

What is another name for a hydrogen ion?

A proton.

What is the symbol for a hydrogen ion?

H+.

Why is H+ considered a proton?

Hydrogen has one proton, so after losing its electron only the proton remains.

Are hydrogen ions mobile in biochemical systems?

Yes, they are highly mobile.

What do hydrogen ions help do in biochemical reactions?

Balance charges.

What does pH reflect?

The concentration of hydrogen ions.

What does a high H+ concentration mean?

A low pH.

What does a low H+ concentration mean?

A high pH.

What can pH affect in the body?

Enzyme activity.

Why can pH change enzyme activity?

It can change the charges and shape of amino acids in the enzyme.

What is an electron-rich region?

An area with more electron density.

What charge does an electron-rich region have?

A partial or full negative charge.

What is an electron-poor region?

An area with less electron density.

What charge does an electron-poor region have?

A partial or full positive charge.

What is a neutral molecule?

A molecule with balanced positive and negative charges.

What happens between opposite charges?

They attract.

What happens between like charges?

They repel.

What happens between a positive and a negative charge?

They attract each other.

What happens between two positive charges?

They repel each other.

What happens between two negative charges?

They repel each other.

What does ATP stand for?

Adenosine triphosphate.

What is ATP?

The cell’s main usable energy molecule.

What are the two major parts of ATP?

Adenosine and three phosphate groups.

What is adenosine made of?

Ribose and adenine.

What type of molecule is ribose?

A sugar.

What is adenine?

A nitrogenous base.

How many phosphate groups does ATP have?

Three.

What charge do ATP’s phosphate groups have?

Negative.

What happens between ATP’s negatively charged phosphate groups?

They repel one another.

Why does ATP have high potential energy?

Its negatively charged phosphate groups strongly repel each other.

What type of bonds connect ATP’s phosphate groups?

Phosphoanhydride bonds.

What happens when ATP’s terminal phosphate bond is broken?

Net energy is released.

What does ATP become after losing one phosphate group?

ADP.

What does ADP stand for?

Adenosine diphosphate.

What is the inorganic phosphate released from ATP called?

Pi.

What are the products of ATP hydrolysis?

ADP and Pi.

What is the general ATP hydrolysis reaction?

ATP → ADP + Pi.

What is ATP hydrolysis?

Breaking ATP using water to release a phosphate group.

What does ATP hydrolysis provide?

Energy for cellular work.

What kinds of cellular work can ATP power?

Movement, transport, synthesis, and signaling.

What is phosphorylation?

Adding a phosphate group to a molecule.

What happens when ADP gains a phosphate?

It becomes ATP.

Does ATP simply contain “energy” inside a bond?

No. Its hydrolysis causes a favorable change that releases usable energy.

Why is ATP hydrolysis favorable?

It reduces repulsion between negatively charged phosphate groups.

What organelle produces most ATP in eukaryotic cells?

The mitochondrion.

What is the plural of mitochondrion?

Mitochondria.

What are the two important mitochondrial compartments in this video?

The intermembrane space and the matrix.

What is the mitochondrial matrix?

The inner central compartment of the mitochondrion.

What is the intermembrane space?

The space between the inner and outer mitochondrial membranes.

Where is proton concentration higher during oxidative phosphorylation?

In the intermembrane space.

Where is proton concentration lower during oxidative phosphorylation?

In the matrix.

What is a concentration gradient?

A difference in concentration between two areas.

What is a proton gradient?

A difference in H+ concentration across a membrane.

Which way do particles naturally move down a concentration gradient?

From high concentration to low concentration.

Which way do protons naturally want to move in the mitochondrion?

From the intermembrane space into the matrix.

What is an electrical gradient?

A force caused by differences in charge.

What is an electrochemical gradient?

The combined effect of concentration and electrical gradients.

What two forces drive protons across the inner mitochondrial membrane?

The concentration gradient and the electrical gradient.

What is ATP synthase?

A membrane protein that uses proton flow to make ATP.

Where is ATP synthase located?

In the inner mitochondrial membrane.

What passes through ATP synthase?

Protons.

What does ATP synthase act like?

A gate or turbine.

What powers ATP synthase?

Protons flowing down their electrochemical gradient.

What molecules does ATP synthase combine?

ADP and Pi.

What molecule does ATP synthase produce?

ATP.

What is chemiosmosis?

The movement of protons down their gradient through ATP synthase.

What does chemiosmosis directly power?

ATP synthesis.

What is oxidative phosphorylation?

The process of using electron transport and a proton gradient to make ATP.

Where does oxidative phosphorylation occur?

Across the inner mitochondrial membrane.

Why do mitochondria need separate compartments?

To maintain different proton concentrations.

Why is the inner mitochondrial membrane important?

It prevents protons from freely moving back into the matrix.

Why do protons need ATP synthase to return to the matrix?

The inner membrane is not freely permeable to protons.

What happens if the proton gradient disappears?

ATP production decreases.

What happens if protons leak across the membrane without passing through ATP synthase?

Less ATP is produced.

What kind of energy is stored in a proton gradient?

Potential energy.

What is another name for the stored energy in a proton gradient?

Proton-motive force.

What does proton-motive force include?

A chemical gradient and an electrical gradient.

What happens to the energy of the proton gradient when protons move through ATP synthase?

It is used to form ATP.

What is the water-turbine comparison for ATP synthase?

Flowing protons turn ATP synthase like flowing water turns a turbine.

What is the main difference between electrons and protons in ordinary biochemical reactions?

Electrons move, while nuclear protons usually remain unchanged.

What changes during many biochemical reactions?

The location or sharing of electrons.

What usually does not change during biochemical reactions?

The identity of the element.

What is the charge of an electron?

Negative.

What is the charge of a proton?

Positive.

What is the charge of H+?

Positive.

What is the charge relationship between H+ and a negative group?

They attract.

What is the charge relationship between two phosphate groups in ATP?

They repel.

What is the major purpose of oxidative phosphorylation?

To produce ATP.