BIOCHP6

_______ energy is a form of potential energy stored within the covalent bonds of molecules. Name the type of energy that is a form of potential energy stored in chemical bonds.

Chemical

During a chemical reaction, which molecules become oxidized?

Molecules that have an electron removed

_________ energy is the energy required to destabilize existing chemical bonds and initiate a chemical reaction.

activation

In order to be initiated, all chemical reactions, even exergonic ones, need

activation energy

Thermodynamics

branch of chemistry concerned with energy changes "heat changes"

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

endergonic reaction

During each step of the metabolic pathway that adds phosphate groups to various sugars, a separate ______ is needed to catalyze the reaction.

enzyme

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

exergonic reaction

True or false: Biochemical pathways evolved quickly over time.

false

True or false: When an electron is added to a molecule, the molecule is oxidized.

false, addition of an electron is called reduction

In the earliest cells, the first catalyzed chemical reactions were probably reactions composed of how many steps?

one

Which of the ATP's phosphate bonds is hydrolyzed in most cellular reactions?

outermost

energy

the capacity to do work

1 joule equals

0.239 cal.

One kilocalorie equals

1000 calories

How much energy is released when the outermost phosphate bond of ATP is hydrolyzed under standard conditions?

7.3 kcal/mol

When you consider the second law of thermodynamics, which of the following is more likely to occur?

A column of bricks tumbles over Soda fizzes Ice melts

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

A considerable amount of energy is released

What is entropy?

A measure of disorder or randomness in a system

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.

The two main steps in the ATP cycle are the synthesis of ATP from ________ and Pi, and the subsequent hydrolysis of ATP, which releases _____ that drives endergonic reactions.

ADP, energy

What molecule is a common energy source for living organisms? All cells use a molecule called _______ to carry and release energy cyclically Cells use ________ hydrolysis to drive endergonic reactions.

ATP

Which of the following are included in metabolism?

Both the synthesis and breakdown of organic molecules

Select the statements that correctly describe differences between anabolic and catabolic reactions.

Catabolic reactions release energy, while anabolic reaction need energy input. In catabolic reactions large molecules are broken down, while in anabolic reactions large molecules are made from smaller ones.

Select the true statements about endergonic reactions.

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

What is the first law of thermodynamics?

Energy cannot be created or destroyed

Which of the following is another way to state the second law of thermodynamics?

Entropy increases. the overall entropy in the Universe is constantly increasing

What statement describes metabolism?

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

Hydrolysis of which covalent bonds in ATP releases a considerable amount of energy?

Phosphate-phosphate bond

Select reasons why metabolic pathways are regulated.

Regulation allows cells to operate efficiently. By regulating metabolic pathways, cells conserve raw materials. By regulating metabolic pathways, cells waste less energy.

Select the steps in the ATP cycle.

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

How does feedback regulation regulate enzyme activity?

The final product of a metabolic pathway inactivates the first enzyme in the pathway by binding to its allosteric site.

What is the second law of thermodynamics?

The second law states that transfer of energy from one form to another increases entropy.

Certain reactions in cells are endergonic. How do cells make those reactions proceed?

They couple them with ATP hydrolysis.

Which of the following is true about spontaneous energy transformations?

They proceed to convert matter from a more ordered to a less ordered form.

In a chemical reaction, an electron is transferred from molecule X to molecule Y. Which of the two molecules is oxidized in this reaction?

X, being transferred

Cells harvest energy during __________ reactions and expend energy during ___________ reactions

catabolic, anabolic

The process of influencing chemical bonds to lower the activation energy of a reaction is called

catalysis

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

_________ stored in the chemical bonds of a molecule can be used to make new bonds in a different molecule. 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 All activities of living organisms involve changes in ______. which is the ability to do work The first law of thermodynamics states that the total amount of _______ in the universe remains constant All living things require which of the following, in order to carry out chemical reactions and thereby survive?

energy

kinetic energy

energy of motion

According to the second law of thermodynamics, _______ increases when energy is transferred from one form to another and some energy is lost as heat in the process..

entropy

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

false- cells routinely use the energy stored in some chemical bonds to make new bonds.

What is the term used to describe the energy of a system that is available to do work? The energy available to do work in a system is called

free energy

When a physical system becomes more disordered, the entropy In general, energy transformations can proceed spontaneously when disorder _______

increases

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

kinetic

Heat is a measure of the random _______ of molecules

motion

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

reversible

potential energy

stored energy

With very few exceptions, all energy that enters biological systems ultimately comes from the

sun

True or false: Thermodynamics is the study of energy changes in the Universe. True or false: Each step of a metabolic pathway is catalyzed by a specific enzyme.

true