Biology 1002B Lecture Notes - Lecture 3: Exergonic Reaction, Kinetic Energy, Chemical Energy

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13 Jun 2018

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Reading Outcomes

Meaning of potential, kinetic, chemical energy

- Kinetic energy is the energy possessed by an object because it is in motion (ex. flow of e-)

- Potential energy is stored energy, the energy an object has because of its position or

chemical structure

- Chemical energy present in a molecule has to do with the position of electrons within its

atoms (the farther away an electron is from the nucleus of an atom the greater potential

energy that electron possesses)

Closed, open vs. isolated systems

- A closed system can exchange energy, but not matter, with its surroundings

- an open system, both energy and matter can move freely between the system and the

surroundings

- An isolated system is one that does not exchange matter or energy with its surroundings

First Law of Thermodynamics, Second Law of Thermodynamics

- 1st Law: energy can be transformed or transferred, but it cannot be created or destroyed

- 2nd Law: the entropy of a system and the surroundings will increase, energy will always

become more spread out

Entropy as energy spreading

- whenever a chemical reaction results in an increase in the number of molecules, entropy

increases

- increases because the energy has spread out over a greater number of molecules

- increases when a solid is converted into a liquid or a liquid into a gas

Gibbs Free Energy (∆G = ∆H - T∆S)

- determines spontaneity

- Exergonic: a spontaneous process where the free energy of the products is less than the free

energy of the reactants, ΔG is negative

- Endergonic: a non-spontaneous process where the free energy of the products is greater

than the free energy of the reactants, ΔG is positive

- Classic example: melting water. The large positive TΔS is greater than ΔH (even though it’s

endothermic +), making ΔG for the reaction negative

Enthalpy

- The total potential energy of a system

- Exothermic: releases energy to surroundings, the products have less potential energy than

the reactants

- Endothermic: absorb energy from the surroundings, result in the products having more

potential energy than the starting molecules

Distinction among the terms: exothermic, endothermic, exergonic, endergonic

- Exothermic: releases energy to surroundings

- Endothermic: absorbs energy from surroundings

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- Exergonic: spontaneous process where free energy is released

- Endergonic: non-spontaneous process where free energy is absorbed

Why the breakdown of glucose increases entropy

- The reaction between molecules of carbon dioxide and water that produces glucose and

oxygen requires energy to occur, but the reverse reaction can take place all by itself

- All biological molecules break down (entropy increases). This is why a constant supply of

energy (food) is required to sustain all life

- releases energy and disordered molecules into the environment, the second law of

thermodynamics is upheld, as the entropy of the system and its surroundings increases

Lecture 6 Outcomes

Cells as open systems and how they maintain low entropy

- thermodynamically open because they exchange energy and matter with their surroundings

- they bring in energy and matter to sustain life

- cells need energy to do work (taking things that are disorganized & combine them to make

something that has structure and function, ex. protein synthesis)

- cells maintain low entropy by counter-acting the break down of molecules by performing work

(cellular processes)

Why we need to eat

- the cellular processes decrease entropy in the cell, but then the macromolecules will break

down (half-lives), when it spreads out (proteins turn into many amino acids) it releases energy

and allows the cells to harvest the energy again to do work

Components of Gibbs Free Energy equation and how they affect whether or not a

reaction will be spontaneous

- ∆G = ∆H - T∆S

- Free Energy (∆G) can be + Endergonic, or - Exergonic

- Enthalpy (∆H) can be + Endothermic, or - Exothermic

- Entropy (∆S) can be + More Spread Out, - Less Spread Out

- Reactions tend to be spontaneous (-∆G exergonic) when rxn is A > B, they occur as written

- bond energy in products - reactants is a contributing factor to how much free energy you have

Exergonic reaction energy profile

- the free energy difference between reactants and products

- exergonic: the change in free energy is negative because free energy of products is less than

reactants (spontaneous)

Transition state and energy of activation

- Activation Energy (EA): the free energy required for the reaction to occur

- Transition State: bonds are about to break, requires free energy

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Document Summary

Kinetic energy is the energy possessed by an object because it is in motion (ex. flow of e-) Potential energy is stored energy, the energy an object has because of its position or chemical structure. Chemical energy present in a molecule has to do with the position of electrons within its atoms (the farther away an electron is from the nucleus of an atom the greater potential energy that electron possesses) A closed system can exchange energy, but not matter, with its surroundings. An open system, both energy and matter can move freely between the system and the surroundings. An isolated system is one that does not exchange matter or energy with its surroundings. First law of thermodynamics, second law of thermodynamics. 1st law: energy can be transformed or transferred, but it cannot be created or destroyed. 2nd law: the entropy of a system and the surroundings will increase, energy will always become more spread out.

Related Questions

As entropy increases there will be more useful energy to doâworkâ. True or false?

False. As entropy increases, there will generally be less usefulenergy to do work. We can think of entropy as usually being presentin the form of heat energy. Imagine a car motor, which attempts toturn chemical potential energy into kinetic energy (movement). Lessefficient motors will get hotter for the same amount of fuelconsumed. When you drive a car you hope that most of the fuelenergy is converted into kinetic energy and not lost as heat(entropy). The hotter the car (and thus the more entropy) the lessefficient the ability to do âworkâ (the moving of the vehicle).

True. As entropy increases, there will generally be more usefulenergy to do work. We can think of entropy as usually being presentin the form of heat energy. In most biological and mechanicalsystems it is heat energy which is captured to do useful 'work'.Heat energy, the random movement of molecules, and increases inentropy are central to doing useful work.

Biological systems sometimes appear on the surface to break theSecond Law of Thermodynamics â by seemingly increasing the order inthe overall system. They donât. Why?

a. Earth (and living things on it) are not a closed system. Thesun's constant input of energy in the form of photons is harnessedby living things to create internal order within themselves. Butwithout such a constant input of energy, most biological systems onearth would break down.

b. The Second Law tells us that no natural process can occurunless it is also associated with an increase in the entropy of theuniverse. A living organism (such as an animal or plant) brings inmatter and energy from its environment and uses this to creategreater order within its body: the processes of life. But it isimportant to keep in mind that all animals and plants are also partof a larger system of the environment around them. While creating asmall âpocketâ of order, the processes of life (metabolism,movement, etc..) releases heat into the environment â thusincreasing the entropy of the universe and following the2^nd law.

c. Living things, by harnessing energy to create order (withinand around themselves) actually create a paradox in questionssurrounding the first and second laws of thermodynamics andseemingly violate many previously held assumptions.

d. Both a and b above are correct.

When plants capture energy in the photons of sunlight andconvert that energy into the chemical bonds of organic molecules,are they creating new energy?

No, the energy is being transferred from one form into another.But no new energy is being created.

No, the overall total energy is decreasing over time.

Yes, by capturing photons, the plants are creating newenergy.

Yes, by capturing photons, the plants are creating new energy -of a different wavelength.

ceruleanhamster867

Question 1 When energy changes from one form to another, some of the energy that can be used to do work is always lost. The loss of this energy is mostly in the form of _________.
a. heat
b. potential energy
c. kinetic energy
d. light energy
e. mechanical energy

Question 2 Which of the following is exergonic?
a. binding fatty acids and glycerol molecules together to form lipids
b. building proteins from amino acids
c. binding sugars molecules together to form glycogen
d. breaking bonds in starch to release glucose
e. adding a phosphate group to ADP to form ATP

Question 3 The first law of thermodynamics states that:
a. energy can neither be created nor destroyed.
b. the universe is increasing in entropy.
c. all living organisms must eat to derive energy.
d. energy is required to bring molecules into a cell against a concentration gradient.
e. in energy-yielding reactions, matter goes from a more-ordered to a less-ordered state.

Question 4 Which of the following is true of energy?
a. It can be transferred from one form to another with 100 percent efficiency.
b. It can be created.
c. It can be stored in chemical bonds.
d. It can never be stored.
e. It can be released by forming chemical bonds.

Question 5 Metabolism is:
a. the sum of all the energy a cell uses.
b. the sum of all the vitamins a cell contains.
c. the sum of all the enzymes a cell contains.
d. the sum of all the chemical reactions that an organism carries out.
e. the sum of all the ATP a cell contains.

Question 6 Entropy is the measure of ________ in a system.
a. disorder
b. order
c. energy
d. work
e. heat

Question 7 What percentage of the energy stored in glucose are humans cells able to use to do useful work?
a. 37%
b. 100%
c. 15%
d. 52%
e. 48%

Question 8 What is activation energy?
a. the energy gained by living things, allowing them to remain active
b. the energy produced by the breakdown of ATP to ADP.
c. the energy required to initiate or begin a chemical reaction
d. the energy created by enzymes during exergonic reactions
e. the energy lost by living things in the form of heat

Question 9 Which of the following is true of allosteric enzymes?
a. Their activity can be reduced when the product binds the enzyme.
b. Their activity can be reduced when a coenzyme binds to them.
c. Their activity can be reduced when the substrate binds the enzyme.
d. Their activity can be increased when the product binds the enzyme.

Question 10 Which of the following is a true statement about enzymes?
a. They are made of proteins.
b. They are altered by the reactions they catalyze.
c. They increase the energy of activation of chemical reactions.
d. All of the above are true.
e. None of the above is true.

Question 11 What is the energy currency of cells?
a. ADP
b. enzymes
c. glucose
d. vitamins
e. ATP

Question 12 Kinetic energy is ____________, while potential energy is _____________.
a. stored energy; energy that is being used
b. stored energy; energy that can't be used
c. energy that is being used; stored energy
d. energy that can't be used; stored energy

Question 13 The energy released during ________ reactions can be used to drive ________ reactions, and this is called ________ reactions.
a. exergonic; endergonic; coupled
b. endergonic; exergonic; coupled
c. exergonic; endergonic; mutually dependent
d. coupled; mutually dependent; independent
e. endergonic; exergonic; mutually dependent

Question 14 ADP + P + Energy --> ATP Which of the following is a true statement about the chemical reaction above?
a. This is a coupled reaction.
b. This is an exergonic reaction.
c. The product of the reaction contains more energy than that of all of the reactants combined.
d. This is an endergonic reaction.
e. This is an example of a catabolic reaction.

greychimpanzee211

1.When something appears blue, it is absorbing all colors except__________.

yellow

blue

red

green

orange

2.During heavy exercise, lactic acid can build up in ourmuscles. Why? How does this resemble the metabolism of bacteria andyeast?

lactic acid is results from insufficient oxygen during sugarmetabolism; it is fermentation

lactic acid accumulates when we are dehydrated; bacteria andyeast use the same pathway

lactic acid is built up from carbon dioxide; bacteria and yeaststore energy in this way

3.Why must a cell keep a similar concentration of dissolvedsubstances with the fluid surrounding them?

to avoid dilution of potential energy

to avoid osmotic imbalance and rapid gain or loss of water

to maintain the correct amount of dehydration and hydrolysis

4.What is entropy?

the amount of energy in a system

the amount of disorganization

the amount of organization

5.Burning a log is the reverse reaction found in photosynthesis.What products would be formed in burning a log?

carbon dioxide and water

glucose and oxygen

oxygen and carbon dioxide

oxygen and water

6.The main reason that cellular respiration needs to occur stepby step instead of a single, big reaction is

cells don't store enough oxygen

too much energy would be released for the cell to harness

cells don't have many mitochondria.

cells produce the enzymes needed for cellular respiration veryslowly

7.Enzymes are catalysts because they operate to:

raise activation energy

lower activation energy

supply activation energy

supply the reactants

8.When ATP powers a reaction it becomes ADP. The ADP

can reform ATP by an exergonic reaction

is a waste product for lysosomal breakdown

can reform ATP by an endergonic reaction

can reform ATP by an oxidation reaction

can reform ATP by an equilibrium reaction

9.The energy source that drives photosynthesis is

water

glucose

carbon dioxide

oxygen

sunlight

10. What is the process by which enzymes regulate their ownactivity?

osmosis

self-propulsion

feedback inhibition

11.Coupled reactions are reactions in which a

endergonic reaction drives a spontaneous reaction

exergonic reaction drives a spontaneous reaction

endergonic reaction drives an exergonic reaction

exergonic reaction drives an endergonic reaction

12.How is water used in photosynthesis?

as a substrate for ATP synthase

as an electron donor

to combine with ADP forming ATP

as an electron acceptor

13.Why are the âDark Reactionsâ of photosynthesis referred to asâDarkâ?

they do not require light

they can only occur at night

they generate excess sugar and the leaves turn brown

14.What is the difference between potential and kineticenergy?

potential is stored, kinetic is being used

potential is being used, kinetic is ready to be used

potential is negative, kinetic is positive

15.The products of cellular respiration are

carbon dioxide, water, and ATP

glucose, water, and ATP

glucose, carbon dioxide, and ATP

oxygen, ATP, and water

carbon dioxide, glucose, and water

16.All of the following are correct about energy except:

The biological world gets its energy from the sun.

Chemical bonds store potential energy.

A boulder perched on a hill has kinetic energy.

Energy is defined as the ability to do work.

All forms of energy can be converted to heat.

17.What is needed for the end product of glycolysis, pyruvate,to enter the citric acid cycle?

More glucose for energy

ATP

Oxygen

Carbon dioxide

18.The enzyme that forms a transmembrane channel in mitochondriaand phosphorylates ADP

a carrier protein

ATP synthase

acetyl CoA

19.Fermentation is most common in

plants

microorganisms

animals

20.During adsorption of sunlight by photosystems, H+ ions aregenerated. Where do they come from? What are they used for?

from the breakdown of sugar; they help form water

water; they help form sugar

from carbon dioxide; they help dissolve NaCl

21.Glycolysis

does not use oxygen

uses oxygen

uses carbon dioxide

22.Photosynthesis is

not dependent on chlorophyll

a process that produces glucose and oxygen

a process that produces water and carbon dioxide

23.Breakdown of glucose generates many ATP molecules, each ofwhich can be used independently. Why is ATP ideally suited to powerbiological reactions?

ATP has many hydrogen bonds

ATP has enough energy to power one biological reaction

ATP readily dissolves in water

24.Objects that are not actively moving but have the capacity todo so are said to possess:

kinetic energy

entropy

potential energy

living energy

25.The first stage of cellular respiration, called ___________,takes place in the cytoplasm of the cell and needs no oxygen.

photorespiration

citric acid cycle

glycolysis

oxidation

26.Diffusion

requires energy

utilizes proteins to move molecules across a membrane

moves molecules against a concentration gradient

does not require energy

cannot occur without a membrane present

27.What is the name of the molecule on which an enzymeworks?

substrate

monomer

polymer

28.ATP contains

phenylalanine

two phosphate groups

three nitrate groups

three phosphate groups

29.How does chlorophyll function in photosynthesis?

by absorbing carbon dioxide

by absorbing the sun's energy

by absorbing water

30.Objects that are moving are said to possess:

living energy

potential energy

entropy

kinetic energy

31.The respiration pathway that evolved first is probably

glycolysis

aerobic respiration

citric acid cycle

32.The energy source for the process of photosynthesis is

oxygen

sunlight

carbon dioxide

chlorophyll

glucose

33.Burning wood generates heat and light. What type of reactionis this?

exergonic

kinetic energy

endergonic

potential energy

equilibrium

34.What is meant by a âcoupled reactionâ in terms of energy?

many poymers are built simultaneously

energy released by one reactions powers another reaction

some reactions occur in the same organelle

35.The First Law of Thermodynamics states:

energy is constantly being created by entropy events

energy can be changed from one form to another, but cannot becreated or destroyed

energy can be used and then destroyed because of entropy'sactions on it

energy can be destroyed while it is producing entropy

36.How do we dispose of the carbon derived from the glucose thatis metabolized during respiration?

by breathing out

via our urine

it is broken down in lysosomes

37.Both plant and animal cells have mitochondria because theyboth

carry on respiration

carry on photosynthesis.

require water

38.What is Activation Energy?

the energy needed to initiate a reaction

the energy that transports water into cells

potential energy

39.If you put a plant in a chamber and shine a light on it

oxygen will decrease and carbon dioxide will increase

oxygen will increase and carbon dioxide will decrease

oxygen and carbon dioxide will increase

oxygen and carbon dioxide will decrease

40.What are the inputs and the output molecules for the overallphotosynthetic process?

input sugar and oxygen; output carbon dioxide and water

input oxygen and water; output sugar and carbon dioxide

input carbon dioxide and water;output sugar and oxygen

41.What kind of reaction is photosynthesis?

endergonic

kinetic energy

exergonic

potential energy

equilibrium

42.In the process of glycolysis, glucose is cleaved into a pairof three-carbon molecules called

lactate

pyruvate

acetyl CoA

ATP

alcohol

43.Entropy is

order

disorder

complexity

Both order and disorder are correct

Both complexity and disorder are correct

44.Glycolysis takes place in the _____________ and the citricacid cycle and electron transport chain take place in the___________.

cytoplasm; endoplasmic reticulum

mitochondria, chloroplast

mitochondria; cytoplasm

cytoplasm; mitochondria

45.The organelle that carries out photosynthesis in plants isthe

mitochondria

chloroplast

ribosome

chlorophylllysosome

46.The energy to power the Calvin cycle comes from

cellular respiration

oxygen

the light reactions of photosynthesis

47.Which of the following can be broken down into intermediateproducts that enter cellular respiration?

Proteins

Lipids

Carbohydrates

All of these.

48.When cellular product levels get too high, the responsibleenzyme is inhibited. This is an example of

promotion

denaturation

equilibrium

a coenzyme

feedback inhibition

49.How is respiration the opposite of photosynthesis?

respiration breaks sugar down to carbon dioxide; photosynthesisbuilds sugar from carbon dioxide

respiration builds sugar from carbon dioxide; photosynthesisbreaks sugar down to carbon dioxide

respiration requires energy input; photosynthesis gives offexcess energy

50.The molecule that absorbs sunlight for photosynthesis is

oxygen

carbon dioxide

chlorophyll

glucose

sunlight

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Biology 1002B Lecture Notes - Lecture 3: Exergonic Reaction, Kinetic Energy, Chemical Energy

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