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Flashcards in Chapter 8 Deck (58):
1

Metabolism

Totality of organism's chemical reactions

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Catabolic pathways

Energy released to break complex compounds to simple compounds

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Anabolic pathways

Energy consumed to build complex compounds from simple compounds

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Cellular respiration is a catabolic/anabolic pathway

Catabolic (spontaneous)

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Energy

Capacity to cause change

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Kinetic energy

Energy of motion

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Thermal Energy

Kinetic energy associated with atom and molecule movements

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Potential energy

Energy matter possesses because of location and structure

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Chemical energy

Potential energy ready for release in chemical reactions

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Complex molecules are high in which type of energy?

Chemical energy; lots of energy can be released when broken down in a catabolic pathway

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Thermodynamics

Study of energy transformations

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First Law of Thermodynamics

Energy cannot be created or destroyed; transferred

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Second Law of Thermodynamics

Every energy transfer increases entropy of universe

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Free Energy

Energy available for conversions

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Why can't all energy be available in free energy transfers?

Some energy is lost as heat

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Spontaneous processes increase/decrease free energy

Decrease; move towards equilibrium in which there is no free energy available

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The equation for free energy can be simplified to...

G = final state - initial

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Equilibrium

State of maximum stability (free energy decreases as reactions reach this)

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A negative free energy means....

Spontaneous/exergonic reaction. Free energy lost, stability increases, less likely to change

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In spontaneous reactions, how does free energy and stability move?

-Free energy: decreases
-Stability: increases

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Respiration is a _______ reaction, while photosynthesis is a ________ reaction (why?)

-Exergonic/spontaneous
-Endergonic
Photosynthesis requires an input of energy, in the form of sunlight

22

Diffusion is what type of reaction and why?

Exergonic because diffused molecules have lower free energy and are more stable

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Exergonic reaction

Energy released to turn reactant to product

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Endergonic reaction

Energy absorbed to turn reactant to product

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What is the defining feature of life?

Metabolism is never at equilibrium, metabolic pathways fuel other reactions)

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Cells does what kinds of work?

Chemical, transport, mechanical

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Energy coupling

Use of exergonic process to drive an endergonic process

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The bonds between phosphate groups in ATP can be broken by what?

Hydrolysis

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The release of energy in ATP hydrolysis comes from what?

Chemical change to a state of lower free energy

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The three types of cellular work are powered by what?

Hydrolysis of ATP

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How does ATP drive endergonic reactions?

Through phosphorylation

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Phosphorylation

Transfer of phosphate group to some other molecule, such as a reactant

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The recipient molecule in phosphorylation is ______

phosphorylated

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ATP is a renewable resource... how is it regenerated?

Addition of phosphate group to ADP

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The energy to phosphorylate ADP comes from what?

Catabolic reactions in cell

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The ATP formation from ADP and P is what type of reaction?

Endergonic; free energy must be spent

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Catalyst

Chemical agent that speeds up reaction without being consumed

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Enzyme

Catalytic protein

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Activation Energy

Initial energy to start chemical reaction

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(pertaining to activation energy) Reactant bonds break only when what? How do they get this?

-The molecules absorb enough to become unstable
-Absorb thermal energy

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Activation energy is typically supplied by what?

Heat from surroundings

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Enzymes do not affect this, but they ______

Don't affect change in free energy, but hasten reactions that would eventually happen

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Active site

Region on enzyme where substrate binds to

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Induced fit

Enzyme changes to conform to substrate shape

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How can the active site lower the activation energy barrier?

Orienting substrates correctly, straining substrate bonds, providing favorable microenvironment, covalently bonding to substrate

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What can enzyme activity be affected by?

-pH and temperature
-Chemicals that influence enzyme

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Cofactors

Nonprotein enzyme helpers

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Coenzyme

Organic molecule cofactor

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Competitive inhibitor

Inhibitor that binds to active site and competes with substrate

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Noncompetitive inhibitor

Inhibitor that binds to another part of enzyme, changing shape to make active site less effective

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Examples of inhibitors?

Toxins, poisons, pesticides, antibiotics

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How does cell regulate metabolic pathways?

REgulating activity of enzymes

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Allosteric regulation

Protein's function at one site if affected by the binding of a different molcule at another site

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How do allosteric regulators inhibit and stimulate enzyme activity?

-Inhibitor stabilizes inactive form of enzyme
-Activator stabilizes active form of enzyme

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Feedback inhibition

End product of a metabolic pathway shuts down the pathway

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Hydrolysis is what type of reaction?

Exergonic

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Coupling involves transfer of energy with ______ to ______

Inorganic phosphate to a reactant

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What would happen if organisms didnt have input of free enregy?

Entropy increases, death occurs