BIOL1020 Lecture Notes - Lecture 6: Endergonic Reaction, Exergonic Reaction, Polymerization

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blueclam798

20 May 2018

School

Department

Biology

Course

BIOL1020

Professor

Dr Paul Ebert

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L6 - cellular energy conversion !

Energy: the capacity (of a system) to do work) is constantly interconverted by living organisms.!

Potential energy: has the capacity to be released but is in stored form. !

Metabolism

•in living cells, energy conversion is linked to chemical reactions called metabolism !

•It transforms matter and energy, subject to the laws of thermodynamics!

•Some cellular processes that require energy: DNA replication, muscle contraction, protein

synthesis !

Laws of thermodynamics

First law of thermodynamics:

The energy of the universe is constant. Energy can be transferred and transformed, but it cannot

be created and destroyed. !

Second law of thermodynamics:

Every energy transfer or transformation increases the entropy (‘disorder’) of the universe. !

Open and closed systems

•an open system [like a living organism] needs constant energy input to maintain itself, because it

is always losing energy to the universe!

•Open systems are at dependancy with the environment and cannot generate energy for

themselves (eg: organisms)!

•Closed systems can operate from the energy within them and no energy can be transferred to

them. !

Gibbs free energy

•the amount of available energy in a system that can be used to do work while pressure and

temperature are constant. !

•This is how scientists refer to energy exchanges between living organisms and surroundings !

•For a chemical reaction, the most important parameter is the CHANGE in the Gibbs free energy

(Delta G) that occurs during the reaction. !

•all metabolic reactions can be classiﬁed based on the change in free energy (G) during the

reaction!

•Metabolic reactions can break down molecules / release energy (catabolic reactions, neg△ G)

•Metabolic reactions can synthesis molecules / consume energy (anabolic reactions, pos △G)!

Exergonic reactions (catabolic reactions) !

•have negative change in Gibbs free energy !

•Spontaneous reaction (it only needs a bit of energy and after that, the reaction will continue

itself)!

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•The reactant (complex molecule) has lots of energy. The energy is lost through the breakdown

process so the product (simple molecule) is low in energy. !

•Exergonic reactions increase the entropy of a system. !

•△G does not look at the curve; only the

initial and ﬁnal energy of the reactant and

product. !

Endergonic reactions (anabolic reactions)

•has positive change in Gibbs free energy !

•Reactants (small molecules) are low in energy. Energy is consumed during the polymerisation

process etc to make the product which is high in energy. !

•Most reactions that synthesis cellular material are endergonic reactions.

Comparison of exergonic and endergonic reactions

The diﬀerence

between -thermic and

-gonic is that thermic

refers to heat and

gonic refers to energy

Use of energy !

•cell store the exergonic released energy as ATP

(adenosine triphosphate) for later use!

•ATP contains chemical energy in the bonds of the

3 phosphate group. !

•Energy from nutrients is converted to ATP!

•ATP is broken down into ADP (1 phosphate

removed) and this energy is released and can be used. !

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Document Summary

Energy: the capacity (of a system) to do work) is constantly interconverted by living organisms. Potential energy: has the capacity to be released but is in stored form. Metabolism: in living cells, energy conversion is linked to chemical reactions called metabolism, it transforms matter and energy, subject to the laws of thermodynamics, some cellular processes that require energy: dna replication, muscle contraction, protein synthesis. Energy can be transferred and transformed, but it cannot be created and destroyed. Every energy transfer or transformation increases the entropy ( disorder") of the universe. Exergonic reactions (catabolic reactions: have negative change in gibbs free energy, spontaneous reaction (it only needs a bit of energy and after that, the reaction will continue itself, the reactant (complex molecule) has lots of energy. Endergonic reactions (anabolic reactions: has positive change in gibbs free energy, reactants (small molecules) are low in energy.

Related Questions

......Use the following to feel out the sentense: cycled, photosynthesis, cellular respiration, oxygen, carbon dioxide, ATP

During ____________ , mitochondria break down carbohydrates to produce energy that is used to make ____________ .

This process requires ____________ and carbohydrates, and produces ____________ and water.

During ____________ , chloroplasts use water and ____________ to create carbohydrates.

This process requires ____________ and water, which are byproducts from ____________ .

In turn, it produces ____________ and carbohydrates that are used in ____________ .

In this manner, the flow of energy is ____________ between chloroplasts and mitochondria.

..........use the following to feel out each sentense: from, oxidized, photosynthesis, cellular respiration, gains, to, loses, reduced.

During ____________ , hydrogen atoms are transferred ____________ water ____________ carbon dioxide as glucose forms.

Thus, during ____________ , carbon dioxide is ____________ , while water is ____________ . In other words, carbon dioxide ____________ electrons and water ____________ electrons.

During ____________ , glucose is ____________ as oxygen is ____________ , becoming water.

In each of these reactions, while one molecule loses electrons (is ____________ ), another gains electrons (is ____________ ); thus, each of these metabolic pathways includes redox reactions: coupled reduction and oxidation reactions.

..........use the following to feel out the sentenses: increase, conservation of energy, first of thermodynamics, input, decrease, laws of thermodynamics, secod law of thermodynamics, heat

The ____________ explain energy flow and energy conservation and can be applied to biological systems.

The ____________ states that energy cannot be created or destroyed, also known as the law of ____________ .

The ____________ states that energy is lost when it is converted from one form to another, often in the form of ____________ .

As cells go through transformations, they ____________ the total entropy of the universe, resulting in a ____________ in available energy.

For example, photosynthesis in plants requires an energy ____________ to turn carbon dioxide and water into sugar because there is a ____________ in entropy.

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.

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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.

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BIOL1020 Lecture Notes - Lecture 6: Endergonic Reaction, Exergonic Reaction, Polymerization

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