BIO227: Chapter 3- energy, chemical reactions, and enzymes

what is energy

energy is the capacity to do work

the energy of motion is ____ energy

kinetic

the type of potential energy that is stored in a molecule’s chemical bonds is called ____ energy

chemical

which function(s) primarily as energy storage in the human body

glycogen and triglycerides

the energy of electromagnetic waves is ___ energy

radiant

the movement of charged particles is ____ energy

electrical

the energy of position or stored energy is _____ energy

potential

A ball rolling across a table exhibits ____ kinetic energy

mechanical

what is true of chemical energy

chemical energy is used for synthesis of molecules, chemical energy is used to establish concentration gradients, chemical energy is a form of potential energy

the vibrating string on a violin imparts ____ kinetic energy to the air around it

sound

glucose is stored in the liver and muscles in the form of a polymer called ___

glycogen

A type of kinetic energy in the form of electromagnetic waves is ___ energy

radiant

T or F? the heart moves blood by imparting electrical energy to the blood

false

T or F? heat energy is usually available to do work

false

what form of kinetic energy is imparted by the tympanic membrane

sound energy

the measurement of heat energy is called _____

temperature

what has the highest amount of radiant energy

gamma rays

the study of energy transformations is called ____

thermodynamics

the collective term for all of the chemical reactions in a living organism is _____

metabolism

the movement of charged particles is _____ energy

electrical

what is the kinetic energy that is associated with random motion of atoms, ions, or molecules

heat

the substances present at the beginning of a chemical reaction are called _____

reactants

the combination of all catabolic and anabolic chemical reactions is referred to as ______

metabolism

chemical reactions can be classified based on changes in chemical _________

structure

the movement of ions across a membrane is an example of ____ energy

electrical

which type of reaction results when a large molecule breaks down into smaller molecules

decomposition

a method of writing a summary of the changes that occur in a chemical reaction is a ____ equation

chemical

which of the following are criteria for classifying chemical reactions

changes in chemical energy, changes in chemical structure, reversibility or irreversibility

the propagation of an impulse in a neuron is an example of _____ energy

electrical

catabolic reactions are ____ reactions

decomposition

what describes all the decomposition reactions in the body

catabolism

the collective term for all the synthesis reactions in the body is ____

anabolism

what type of reaction involves both synthesis and decomposition

exchange

the type of chemical reaction that occurs when two or more atoms, ions, or molecules combine to form a larger chemical structure is called a(n) _____ reaction

synthesis

when electrons are transferred from one chemical structure to another, an _____ - _____ reaction occurs

oxidation-reduction

when a molecule or ion loses an electron during a reaction, it is said to have been ____

oxidized

when a molecule or ion gains an electron during a reaction, it is said to have been ____

reduced

a reaction in which electrons are transferred from one chemical structure to another is referred to as a(n) _____

oxidation-reduction reaction

what explains why the term “reduced” is used in an oxidation-reduction reaction?

the addition of an electron makes the product more negatively charged

if an electron and a hydrogen ion are removed from a structure during a chemical reaction, the structure is said to have been ____

oxidized

in the mnemonic, “LEO says GER,” the acronym “LEO” stands for ____

loses electrons oxidized

NADH is the reduced form of NAD+ because _____

NAD+ has gained both a H+ ion and 2 electrons

when electrons move during an oxidation-reduction reaction, they possess ____ energy that can be used to do ____

kinetic; work

exergonic and endergonic terms are used to describe _____

the amount of energy associated with a chemical reaction

in an example exergonic reaction, energy is _____

released

in the mnemonic, “LEO says GER,” the acronym “GER” stand for _____

gains electrons is reduced

the reduced form of NAD+ is _____

NADH

in an endergonic reaction, energy is ____

required

when glucose is oxidized, it ___ chemical energy

releases

what are the terms that can be used to classify reactions based on the relative amounts of energy in reactants and products?

exergonic and endergonic

in an irreversible reaction, reactants are ____

only converted to a product

in an ____ reaction, the amount of energy in the products is less than the amount of energy in the reactants.

exergonic

in a(n) ____ reaction, the reactants become products and the products become reactants again

reversible

reaction rate is the measure of ____

how quickly a chemical reaction takes place

if the rate of a reaction leads to a net loss of reactants, then the reaction is considered ____

irreversible

a biologically active catalyst is known as a(n) ____

enzyme

at equilibrium, a reversible reaction proceeds in ____direction(s)

both reverse and forward

the measure of how quickly a chemical reaction takes place is known as the reaction ____

rate

the activation energy of a catalyzed reaction is _____ that of an uncatalyzed reaction

lower than

in an ____ reaction, the products have more energy than the reactants

endergonic

the smallest enzymes are around ___ amino acids long

60

a molecule or ion that aids an enzyme to ensure a reaction occurs is known as a(n) _____

cofactor

what is true of an enzyme

it is a catalyst, it decreases activation energy, it increases reaction rates

the name of an enzyme is generally bases on the name of the ______ or products involved in a chemical reaction

substrate

an enzyme is saturated if it ____ bind more substrate

cannot

T or F? the presence of an enzyme lowers the activation energy required to start the reaction

true

most enzymes are ____ proteins that range in size from 60 to 2500 amino acids

globular

a substance that binds to an enzyme to stop its action is called a(n) _____

inhibitor

a molecule that assists an enzyme in performing its function is known as a(n) _____

cofactor

the regulation of an enzyme by addition of a phosphate is referred to as ____

phosphorylation

the suffix -ase often signifies a substance is a(n)

enzyme

if further increases in substrate concentration do not result in further increases in reaction rate, then an enzyme is likely ____

saturated

what is the optimal pH range for most human enzymes

6 to 8

enzyme ____ bind to an enzyme to turn it off, thus preventing it from catalyzing a reaction

inhibitors

the process of removing a phosphate is ____

dephosphorylation

potential energy

chemical

kinetic energy

electrical, mechanical, sound, radiant, heat

first law of thermodynamics

energy cannot be created nor destroyed; it can only change in form

second law of thermodynamics

all things tend toward entropy (gasoline)

ATP cycling

ATP formed from energy released in exergonic reactions, energy in their bonds transferred to ADP and free phosphate to form ATP

Reaction rate

measure of how quickly a chemical reaction takes place

activation energy

energy required to break existing chemical bonds, helps determine reaction rate

mechanism of enzyme action

1. substrate enters active site, forming enzyme-substrate complex

2. conformational change = closer fit

3. stresses chemical bonds, permitting new bonds to be formed

4. products released; enzyme may repeat process

cofactors

molecules or ions required for normal enzyme function

6 major classes and their enzymes

oxidoreductase, transferase, hydrolase, isomerase, ligase, lyase

dehydrogenase

enzymes subclass that moves H between molecules

oxidoreductases

catalyze oxidation-reduction reactions

transferases

transfer functional groups between molecules

hydrolases

break bonds by adding water

lyases

cleave bonds without using water

isomerases

rearrange atoms within a molecule to create isomers

ligases

join two molecules together by forming new bonds

kinase

subclass that transfers a phosphate functional group

effects on enzyme and substrate concentration

increase in enzyme concentration, increase in substrate concentration, increase only up to saturation

effects of temperature

increased temperature, increased reaction rate. severe increase in temp. leads to protein denaturation with loss of function

competitive inhibitor

binds to the same active site on an enzyme as the substrate, directly competing for that space

noncompetitive inhibitor

binds to a different site on the enzyme (allosteric site), causing a conformational change that indirectly affects the enzyme’s ability to bind the substrate

what is the general function of enzymes

to speed up chemical reactions by acting as catalysts

what are catalysts

a substance that speeds up a chemical reaction, or lowers the temperature or pressure needed to start one, without itself being consumed during the reaction

what is the activation site of enzymes

the specific region on the enzyme where a substrate molecule binds and undergoes a chemical reaction