Ch. 8

Metabolism

Metabolism

Totality of an organism’s chemical reactions

Metabolic pathway

Begins with specific molecule and ends in product

Catabolic pathway

Release energy by breaking down complex molecules

Anabolic pathways

Consume energy to build complex molecules

Energy

Capacity to cause change

Isolated system

Unable to exchange energy or matter with surroundings

Open system

Energy and matter can be transferred between system and surroundings

First law of thermodynamics

Energy of the universe is constant

Second law of thermodynamics

Every energy transfer or transformation increases the entropy of the universe

Entropy

Measure of molecular disorder or randomness

Spontaneous process

Occurs without energy input

Nonspontaneous processes

Occurs only if energy is provided, decrease entropy

Exergonic

Net release of free energy, spontaneous

Endergonic

Absorbs free energy from surroundings, nonspontaneous

ATP

Cell’s energy shuttle

Catalyst

Speeds up a reaction

Enzyme

Catalytic protein

Activation energy

“Jump start” to make a reaction begin

Substrate

Reactant that an enzyme acts upon

Cofactor

Nonprotein enzyme helpers

Competitive inhibitor

Bind to an active site

Noncompetitive inhibitor

Bind to another part of an enzyme

Allosteric regulation

Either inhibit or stimulate enzyme’s activitt

Feedback inhibition

End product of a metabolic pathway shuts down the pathway

How do inhibitors affect enzymatic activity?

Inhibitors disrupt an enzyme’s function

Which of the following statements describes a central role that ATP plays in cellular metabolism?

ATP provides energy coupling between exergonic and endergonic reactions.

A decrease in entropy is associated with which type of reaction?

Dehydration

Which of the following statements about anabolic pathways is true?

They consume energy to build up polymers from monomers

Which of the following statements is a logical consequence of the second law of thermodynamics?

Each chemical reaction in an organism must increase the total entropy of the universe

How does a noncompetitive inhibitor decrease the rate of an enzyme-catalyzed reaction?

By binding to an allosteric site, thus changing the shape of the active site of the enzyme