Chapter 6 - Energy, Enzymes, and Biological Reactions

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142 Terms

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Slide 2 - 6.1 Energy, Life, and Laws of Thermodynamics

Define Energy

defined as the capacity to do work

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Slide 2 - 6.1 Energy, Life, and Laws of Thermodynamics

Different forms of energy

chemical,

electrical,

thermal,

and radiant energy (including light, gamma rays, and X-rays)

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Slide 2 - 6.1 Energy, Life, and Laws of Thermodynamics

Energy can be converted from one form to another – in plants, the radiant energy of sunlight is transformed into __________ in the form of ________

chemical energy; organic molecules

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Slide 3 - Kinetic Energy and Potential Energy

All forms of energy can exist in one of two states namely _______ or ___________, which are interconvertible

kinetic or potential

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Slide 3 - Kinetic Energy and Potential Energy

Kinetic energy - Define and provide examples

energy of an object in motion

Ex: a falling rock, electricity and light

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Slide 3 - Kinetic Energy and Potential Energy

Potential energy - Define and provide examples

is stored energy

Examples: a rock at the top of a hill, chemical energy, gravitational energy, and stored mechanical energy

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Slide 4 - Energy Flow in Natural Systems

What is Thermodynamics?

study of energy and its transformations

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Slide 4 - Energy Flow in Natural Systems

When discussing thermodynamics, scientists refer to a ________, which is the object under study – everything outside it is the _______.

system

surroundings

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Slide 4 - Energy Flow in Natural Systems

What are the three types of systems?

All living organisms are _____ systems.

isolated, closed, and open systems

open

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Slide 5 - Systems in Thermodynamics

does not exchange matter or energy with its surroundings. Which system?

Isolated

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Slide 5 - Systems in Thermodynamics

exchanges both matter and energy with its surroundings

Open System

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Slide 5 - Systems in Thermodynamics

exchanges energy with its surroundings

Closed System

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Slide 5 - Systems in Thermodynamics - Diagram

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Slide 6 - First Law of Thermodynamics

State First law of thermodynamics

Energy can be transformed from one form to another, or transferred from one place to another, but it cannot be created or destroyed

Also called the principle of conservation of energy

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Slide 6 - First Law of Thermodynamics

In any process that involves energy change, the total amount of energy in a system and its surroundings ______________

remains constant

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Slide 7 - Energy Flow from the Sun

For most organisms, the ultimate source of energy is the _____

sun

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Slide 7 - Energy Flow from the Sun

plants capture kinetic energy of __________and convert it to the __________ of complex organic molecules

light ; chemical potential energy

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Slide 7 - Energy Flow from the Sun

________________ energy stored in sugars and other organic molecules is used for ________, ________, and other work of living organisms

Chemical potential

growth; reproduction

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Slide 7 - Energy Flow from the Sun

Most of the solar energy absorbed by green plants is converted into _______ energy (which is largely unusable by living organisms). and ________ into space

heat

radiated

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Slide 7 - Energy Flow from the Sun - Diagram

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Slide 8 - Second Law of Thermodynamics

Second law of thermodynamics

The total disorder (entropy) of a system and its surroundings always increases (although the total energy in the universe does not change)

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Slide 8 - Second Law of Thermodynamics

Second law of thermodynamics - what is entropy

The total disorder (entropy) of a system and its surroundings

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Slide 8 - Second Law of Thermodynamics

Living organisms seem to _______ in entropy as they grow. When nutrients and waste products are considered, total energy _________ (increases / decreases / remains constant ) and entropy ________ (increases / decreases / remains constant )

decrease ;

remains constant

increases

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Slide 9 - 6.2 Free Energy and Spontaneous Reactions

A chemical or physical reaction that occurs without an input of energy is a

A spontaneous reaction

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Slide 9 - 6.2 Free Energy and Spontaneous Reactions

Two factors related to the first and second laws of thermodynamics that must be considered to determine whether a reaction is spontaneous are:

(1) the change in energy content of a system, and

(2) its change in entropy

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Slide 10 - Energy Content and Entropy

Reactions tend to be spontaneous if the products have [more/less] _______ energy than the reactants

less

potential

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Slide 10 - Energy Content and Entropy

What is enthalpy (H)?

The potential energy in a system is its enthalpy (H)

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Slide 10 - Energy Content and Entropy

Reactions that release energy are ______

exothermic

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Slide 10 - Energy Content and Entropy

Reactions that absorb energy are _______

endothermic

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Slide 10 - Energy Content and Entropy

A reaction where the products have less potential energy than the reactants is an ___________ (exothermic / endothermic) reaction.

endothermic

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Slide 10 - Energy Content and Entropy

In an endothermic reaction, the products have ______(more/less) __________energy than the reactants

more

potential

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Slide 10 - Energy Content and Entropy - Please verify this question

when the products are less ordered (more random) than the reactants, the reactions tend to be __________

spontaneous

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Slide 10 - Energy Content and Entropy - Please verify this question

Reactions tend to occur spontaneously if the entropy of the products is _____________(greater / lesser) than the entropy of the reactants

greater

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Slide 11 - Change in Free Energy (1 of 2)

The portion of a system’s energy that is available to do work is called _____ energy (G)

free

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Slide 11 - Change in Free Energy (1 of 2)

The change in free energy, ΔG can be calculated for any chemical reaction from the formula

<p></p>
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Slide 11 - Change in Free Energy (1 of 2)

ΔH is the change in ___________

enthalpy

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Slide 11 - Change in Free Energy (1 of 2)

T is the _________

absolute temperature in degrees Kelvin (K)

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Slide 11 - Change in Free Energy (1 of 2)

ΔS is the________

change in entropy

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Slide 12 - Change in Free Energy (2 of 2)

For a reaction to be spontaneous, ΔG must be __________

negative

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Slide 12 - Change in Free Energy (2 of 2)

In some processes, such as the combustion of methane, the large loss of potential energy, ___________, dominates in making a reaction spontaneous

negative enthalpy (ΔH)

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Slide 12 - Change in Free Energy (2 of 2)

In other reactions, such as the melting of ice at room temperature, a __________ dominates

decrease in order (ΔS increases)

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Slide 13 - Equilibrium Point

In many spontaneous biological reactions reactants _______ (may / may not) convert completely to products even though the reactions have a negative ΔG

may not

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Slide 13 - Equilibrium Point

The reactions run in the direction of completion (toward reactants or toward products) until they reach the ___________

equilibrium point

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Slide 13 - Equilibrium Point

Define Equilibrium Point

a state of balance between the opposing factors pushing the reaction in either direction

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Slide 14 - Equilibrium Point

As a system moves toward equilibrium, what happens to its free energy when the system c

its free energy becomes progressively lower and reaches its lowest point when the system achieves equilibrium (ΔG = 0)

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Slide 14 - Equilibrium Point

Can moving away from equilibrium be spontaneous?

To move away from equilibrium requires free energy and thus will not be spontaneous

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Slide 14 - Equilibrium Point

The more negative the ΔG, the _______ completion the reaction will move before equilibrium is established

closer to

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Slide 15 - Equilibrium Point of a Reaction

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Slide 16 - Reversible Reactions

Many reactions have a ΔG that is near zero and are readily _________

reversible

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Slide 16 - Reversible Reactions

Reactions are readily reversible by adjusting the concentration of ______________

products and reactants slightly

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Slide 16 - Reversible Reactions

Reversible reactions are written with a double arrow:

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Slide 17 - Reactions in Living Organisms

Many reactions in living organisms never reach equilibrium because of the following:

living systems are open – the supply of reactants is constant and products do not accumulate

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Slide 17 - Reactions in Living Organisms

The ΔG of life is always __________ (positive / negative)

negative

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Slide 17 - Reactions in Living Organisms

Why is ΔG of life is always negative

organisms constantly take in energy-rich molecules and use them to do work

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Slide 17 - Reactions in Living Organisms

At what stage do organisms reach equilibrium?

only when they die

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Slide 18 - Exergonic and Endergonic Reactions

What are the characteristics of an Exergonic reaction?

Reaction that releases free energy

ΔG is negative because the products contain less free energy than the reactants

<p>Reaction that releases free energy </p><p>ΔG is negative because the products contain less free energy than the reactants</p>
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Slide 18 - Exergonic and Endergonic Reactions

What are the characteristics of an Endergonic reaction?

Reactants must gain free energy from the surroundings to form the products

ΔG is positive because the products contain more free energy than the reactants

<p>Reactants must gain free energy from the surroundings to form the products</p><p>ΔG is positive because the products contain more free energy than the reactants</p>
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Slide 18 - Exergonic and Endergonic Reactions

In which of the reactions the ΔG is positive?

Endergonic

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Slide 18 - Exergonic and Endergonic Reactions

In which of the reactions the energy is released?

Exergonic reaction

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Slide 19 - Metabolic Pathways

What is a metabolic pathway?

a series of reactions in which the products of one reaction are used immediately as the reactants for the next reaction in the series

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Slide 19 - Metabolic Pathways

In which pathway, the energy is released by the breakdown of complex molecules to simpler compounds;

catabolic pathway (or a single catabolic reaction)

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Slide 19 - Metabolic Pathways

In a catabolic pathway, the overall ΔG is ____________(positive / negative)

negative

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Slide 19 - Metabolic Pathways

In which pathway, the energy is used to build complicated molecules from simpler ones;

anabolic pathway (or an anabolic reaction or biosynthetic reaction)

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Slide 19 - Metabolic Pathways

In a anabolic pathway, the overall ΔG is ____________(positive / negative)

positive

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Slide 20

ATP stands for

adenosine triphosphate

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Slide 20 - Adenosine Triphosphate (ATP): Energy Currency of the Cell

The nucleotide adenosine triphosphate (ATP) consists of the

__________ linked to the ___________ base adenine and a chain of _________

five-carbon sugar ribose

nitrogenous

three phosphate groups

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Slide 20 - Adenosine Triphosphate (ATP): Energy Currency of the Cell

What makes the bonding arrangement in Phosphate groups unstable?

The negative charges of the phosphate groups repel each other strongly, making the bonding arrangement unstable

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Slide 20 - Adenosine Triphosphate (ATP): Energy Currency of the Cell

Removal of one or two phosphate groups is a _________ reaction that releases ___________

spontaneous

large amounts of free energy

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Slide 21 - Hydrolysis of ATP

The breakdown of ATP is a [hydrolysis/dehydration synthesis] reaction

hydrolysis

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Slide 21 - Hydrolysis of ATP

Hydrolysis of ATP results in ?

results in the formation of adenosine diphosphate (ADP) and a molecule of inorganic phosphate (Pi )

<p>results in the formation of adenosine diphosphate (ADP) and a molecule of inorganic phosphate (Pi )</p>
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Slide 21 - Hydrolysis of ATP

ADP can be hydrolyzed to _______

adenosine monophosphate (AMP)

<p>adenosine monophosphate (AMP)</p>
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Slide 21 - Energy Coupling, using ATP

In the process of energy coupling, when ATP is hydrolyzed, the _______ group is transferred to a __________ involved in an ________ reaction

terminal phosphate

reactant molecule

endergonic

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Slide 21 - Energy Coupling, using ATP

What is phosphorylation?

The addition of a phosphate group to a molecule is called phosphorylation (the modified molecule is phosphorylated)

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Slide 22 - Energy Coupling, using ATP

what are the features of the enzyme that energy coupling requires, and why?

Energy coupling requires an enzyme with a specific site that binds both ATP and the reactant molecule to bring the ATP and reactant molecule into close association

<p>Energy coupling requires an enzyme with a specific site that binds both ATP and the reactant molecule to bring the ATP and reactant molecule into close association</p>
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Slide 23 - Regeneration of ATP

ATP synthesis from ADP and Pi is an _________ reaction that uses energy from the _____________, ___________, and ________(food)

endergonic

exergonic breakdown of carbohydrates,

proteins

fats

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Slide 23 - Regeneration of ATP

The continual hydrolysis and resynthesis of ATP is called the ________

ATP/ADP cycle

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Slide 23 - Regeneration of ATP

Approximately how many ATP molecules are hydrolyzed and resynthesized each second in a typical cell

10 million

<p>10 million</p>
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Slide 24 - 6.4 Role of Enzymes in Biological Reactions

Even when a reaction is spontaneous (negative ΔG), the reaction will not start unless ____________

a small amount of activation energy (Ea) is added

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Slide 24 - 6.4 Role of Enzymes in Biological Reactions

What are the effects of Activation energy on bonds. Explain with an example

unstable and ready to be broken (the transition state)

Example: Activation energy is like the effort required to raise a rock over the rim of a depression and start it rolling downhill

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Slide 25 - Activation Energy Diagram

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Slide 25 - Enzymes Reduce Activation Energy Diagram

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Slide 26 - Enzymes

A catalyst is a chemical agent that ___________ the rate of a reaction without being ______ by the reaction

accelerates (catalyzes)

changed

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Slide 26 - Enzymes

The most common biological catalysts are _____called ________,

proteins

enzymes

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Slide 26 - Enzymes

what is the effect of enzymes on the rate of reaction? and how does it do that?

Enzymes increased the rate of reaction by lowering the activation energy of the reaction

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Slide 26 - Enzymes

Enzymes _______(do/do not) alter the ΔG of the reaction

do not

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Slide 26 - Enzymes

The free energy ___________ (varies / stays the same); the difference is in the path the reaction takes

The free energy stays the same; the difference is in the path the reaction takes

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Slide 27 - Enzymes

What determines the function of a protein? (give the term)

The 3-D structure of a protein (its conformation) determines its function

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Slide 27 - Enzymes

each enzyme has a _________that catalyzes a _________

specific protein structure

specific reaction

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Slide 27 - Enzymes

Cells have thousands of different enzymes, found in different areas inside and outside of the cell

The name of an enzyme typically refers to its ________ or _________, and ends in _______

substrate

type of reaction

–ase (e.g., proteinases)

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Slide 28 - An Enzyme and its Substrate

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Slide 29 - Enzymatic Reactions

What happens in an enzymatic reaction?

an enzyme combines briefly with reacting molecules and is released unchanged when the reaction is complete

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Slide 29 - Enzymatic Reactions

The reactant that an enzyme acts on is called the _____

substrate

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Slide 29 - Enzymatic Reactions

Each type of enzyme catalyzes the reaction of __________ or ___________. this is called ______

a single type of substrate molecule

group of closely related molecules

enzyme specificity

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Slide 29 - Enzymatic Reactions

The substrate interacts with a small pocket or groove in the _________, called the __________

enzyme molecule

active site

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Slide 29 - Enzymatic Reactions

When the substrate binds at the active site, both ______ and _________ are distorted

enzyme

substrate molecules

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Slide 29 - Enzymatic Reactions

What is an induced fit?

When the substrate binds at the active site, both enzyme and substrate molecules are distorted – this makes the chemical bonds in the substrate ready for reaction (induced fit)

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Slide 29 - Enzymatic Reactions

When does a catalysis occur?

What happens in a catalysis?

Catalysis occurs once an enzyme-substrate complex is formed

When catalysis occurs, the substrate is converted into one or more products

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Slide 31 - Catalytic Cycle of Enzymes

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Slide 32 - Cofactors and Coenzymes

What is a cofactor

a nonprotein group that binds to the enzyme, promotes catalytic activity

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Slide 32 - Cofactors and Coenzymes

What does a cofactor help with?

Many enzymes require a cofactor, for catalytic activity