Chapter 6 Energy and Metabolism

All cells use a molecule called ___ to carry and release energy cyclically.

ATP

____ energy s the energy required to destabilize existing chemical bonds and initiate a chemical reaction.

Activation

In the following chemical reaction, which molecule(s) is(are) reduced? Ae- + B --> A + Be-

B

Which of the following are included in metabolism.

Both the synthesis and breakdown of organic molecules.

What is the function of catabolic reactions?

Catabolic pathways are involved in the breakdown of larger molecules into smaller ones.

Any agent that speeds up the rate of a chemical reaction without being permanently changed or consumed by it is known as a(n)

Catalyst

___ energy is a form of potential energy stored within the covalent bonds of molecules.

Chemical

Which of the following statements about chemical reactions are true?

Chemical reactions are reversible. A reaction that is exergonic in the forward direction will be endergonic in the reverse direction.

___ are small organic molecules that temporarily attach to an enzyme and promote a chemical reaction without being changed during the reaction.

Coenzymes

All activities of living organisms involve changes in ____, which is the ability to do work.

Energy

Work in the cell or in the physical world can only be done with expenditure of ___; it is defined as the capacity to do work.

Energy

___ are proteins on RNA molecules that act as catalysts to speed up reactions in living organisms.

Enzymes

When an electron is added to a molecule, the molecule is oxidized.

False

The energy available to do work in a system is called ____ energy.

Free

Select the steps in the ATP cycle

Hydrolysis of ATP to release energy that can be used to drive endergonic reactions. Synthesis of ATP using energy released from exergonic reactions.

Which of the following describes the activity of a particular enzyme?

It can be affected by substances which bind the enzyme and alter its shape.

When the free energy change that occurs as a result of a chemical reaction is ____ than zero, the reaction is spontaneous.

Less

What statement describes metabolism?

Metabolism refers to the sum of all chemical reactions that occur within an organism.

During a chemical reaction, which molecules become oxidized?

Molecules that have an electron removed.

Select all of the following that can occur during the reduction of an atom or molecule.

One or more electrons are added to the atom or molecule. The net charge of the atom or molecule decreases due to negatively charged electron(s).

A fraction of the energy from the sun is captured by plants, algae, and some bacteria through the process of

Photosynthesis

In chemical reactions, ___ refers to the process when one or more electrons are added to the atom or molecule.

Reduction

Chemical reactions are ___, which means that they can proceed in either direction (reactants to products to reactants)

Reversible

Select all of the following that occur during the reduction of an atom or a molecule

The net charge of the atom or the molecule decreases due to the addition of negatively charged electrons. One or more electrons are added to the atom or molecule.

Select the true statements about endergonic reactions.

The products have higher free energy than the reactants. Endergonic reactions have a positive change in free energy. Endergonic reactions are not spontaneous.

How can the functioning of an enzyme be affected by the external environment?

The temperature and pH can greatly affect the function of some enzymes by causing denaturation.

Which of the following is the branch of chemistry concerned with energy changes?

Thermodynamics.

Select the cofactors that are called coenzymes.

Vitamin b6 Vitamin b12

RNA molecules have catalytic properties are called

ribozymes

A reaction that requires an input of energy is said to be a(n) ____ reaction

endergonic

Is any energy released during ATP hydrolysis? And if so, how much?

A considerable amount of energy is released.

Which of the following statements about chemical reactions are true.

A reaction that is exergonic in the forward direction will be endergonic in the reverse direction. Chemical reactions are reversible.

Select the characteristics of enzymes.

Enzymes are not changed or consumed in reactions. Enzymes may be used more than once n a cell. Most enzymes are proteins.

Order the steps in enzyme catalysis starting at the top.

1. Substrate binds to enzyme 2. Amino acids from enzyme interact with substrate. 3. Bonds in substrate(s) are broken and/or created; products form. 4. Products dissociate from the enzyme.

Order the steps in enzyme catalysis

1. Substrate binds to enzyme. 2. Amino acids from enzyme interact with substrate. 3. Bonds in substrates are broken and/or created; products form. 4.Products dissociate from the enzyme.

Cells use ____ hydrolysis to drive endergonic reactions

ATP

What type of reactions are involved in the synthesis of larger molecules from smaller precursor molecules?

Anabolic

Select the reasons why changes in the pH of the fluid in which in which an enzyme in dissolved affect the enzymes ability to function.

Enzymes cannot maintain their three-dimensional shape at extreme pHs. The balance between positively and negatively charged amino acids in the enzyme is shifted.

Catabolic or Anabolic?

Cells harvest energy during catabolic reactions and expend energy during anabolic reactions.

___ are small chemical components, usually inorganic ions, such as Zn2+, Cu2+, and Mn2+, that are often found in the active site participating directly in catalysis.

Cofactors

In photosynthesis, energy absorbed from sunlight is used to

Combine inorganic molecules into organic molecules.

Select the true statements about cellular enzymes.

Each cell has thousands of enzymes. Each enzyme in a cell catalyzes one or a few specif reactions.

Select the statements that are true of exergonic reactions.

Exergonic reactions are spontaneous. Exergonic reactions release energy during product formations.

Energy stored in the chemical bonds of a molecule cannot be harvested and used to make new bonds in a different molecule.

False

Heat is a measure of the random motion of molecules, a form of ___ energy.

Kinetic

In broad terms, energy can exist in two states; ___ energy and ___ energy.

Kinetic and potential

Which of the following statements are correct about a reaction that is endergonic?

The reaction requires an input of energy. The products contain more energy than the reactants.

Select the statements that describe the free energy (G) change of a spontaneous reaction.

There is a negative free energy charge. The free energy of the products is less than the reactants.

Select the true statements about about allosteric enzymes.

They have an allosteric site which differs from the active site. They can exist in either active or inactive form.

Which of the following statements about oxidized molecules are true?

They have less electrons and less energy than reduced molecules.

Each step of a metabolic pathway us catalyzed by a specific enzyme

True

Substances can bind to an enzyme and change its shape, affecting its activity.

True

The oxidized form of a molecule has less energy than its reduced form.

True

What occurs during a redox reaction?

When an atom or molecule is oxidized, the electron that is removed is transferred to another atom or molecule, which is thereby reduced.