chapter 8

summers

What is metabolism?

All of a cells chemical reactions that build up or break down materials.

What is catabolism?

The metabolic pathway that breaks down molecules, releasing energy.

What is anabolism?

The metabolic pathway that builds up molecules, consuming energy.

How are metabolism, catabolism, and anabolism related?

Metabolism encompasses all chemical reactions in a cell, including catabolism and anabolism. Catabolism breaks down molecules to release energy, while anabolism uses energy to build molecules.

What is the First Law of Thermodynamics?

Energy cannot be created or destroyed, only TRANSOFRMED from one form to another.

What is the Second Law of Thermodynamics?

Disorder of the universe increases.

How do the first two laws of thermodynamics apply to cells?

By governing energy transformations within them. Cells transform energy from food into usable forms.

Why must cells be open systems?

To exchange matter and energy with their environment, allowing for the continuous input of nutrients and removal of waste.

What is free energy?

The energy of system that can do work.

What does energy have to do with cellular work?

It enables processes such as synthesis, transport, and movement.

How does free energy change in chemical reactions or processes?

They indicate the direction and spontaneity of the reaction. A decrease suggests spontaneous process, increase indicates non-spontaneity.

How is (DELTA) G calculated?

Using the equation Delta G = Delta H - T/Delta S. Delta H is the change in enthalpy. T is the temperature in Kelvin, and Delta S is the change in entropy.

What does the negative SIGN of (DELTA) G tell you about a reaction or process?

Indicates that the reaction is spontaneous, can occur without external energy, and more favorable.

What does the positive SIGN of (DELTA) G tell you about a reaction or process?

Indicates that the reaction is non-spontaneous, requires energy input, and non-favorable.

What does exergonic mean?

A chemical reaction that releases energy, resulting in a decrease in free energy. (A negative delta G)

What does endergonic mean?

A chemical reaction that absorbs energy, resulting in an increase in free energy. (A positive delta G)

How does the total energy and the entropy change in an exergonic reaction or process?

Total energy decreases while entropy increases, indicating the process is spontaneous and releases energy.

How does the total energy and the entropy change in an endergonic reaction or process?

Total energy increases while entropy may decrease or remain unchanged, indicating the process is non-spontaneous and absorbs energy.

What does favorable / spontaneous mean?

A process that occurs without external energy input, often associated with a decrease in free energy and an increase in entropy.

What does unfavorable / nonspontaneous mean?

A process that requires external energy input to occur, typically associated with an increase in free energy and a possible decrease in entropy.

When can an exergonic reaction drive/fuel an endergonic one?

When the overall change in free energy is negative, allowing the energy released from the exergonic reaction to be utilized in the endergonic reaction.

What is the specific exergonic reaction that is commonly ‘coupled’ to endergonic ones in cells?

The hydrolysis of ATP

What type of monomer is ATP?

A nucleotide that serves as the energy currency in cells,

What are the parts of ATP?

Consisting’s of a ribose sugar, adenine base, and three phosphate groups.

How is ATPs chemical energy liberated?

Through the hydrolysis of its phosphate bonds, releasing energy for cellular processes.

How do cell’s use ATP to drive endergonic reactions?

By coupling the energy released from ATP hydrolysis to the energetically unfavorable reactions, making them favorable.

What other function does ATP have in cells?

Acts as a signaling molecule and participates in the regulation of various metabolic pathways.

What is the activation energy (EA) of a reaction?

The minimum energy required for reactants to undergo a chemical reaction.

What type of kinetic energy allows reactants to overcome the EA?

Thermal energy.

How do enzymes help reactants to overcome EA?

They lower the activation energy by stabilizing the transition state and providing an alternative reaction pathway.

Why does a substrate bind to an enzyme’s active site?

Due to the specificity of the enzyme's shape and chemical environment.

What are examples of what active sites physically do to substrates to speed up chemical reactions?

Orient substrates in the correct position, strain substrate bonds, or provide a microenvironment conducive to the reaction.

What is an allosteric site?

A specific location on an enzyme where molecules can bind, leading to a change in the enzyme's shape and activity, regulating its function.

How does an allosteric site affect an enzyme’s functioning?

It mods enzyme activity by binding effector molecules, leading to conformational changes that can enhance or inhibit activity.

Do all enzymes have allosteric sites?

No only specific ones.

Do all enzymes have active sites?

Yes.

How does substrate concentration affect the rate of an enzyme catalyzed reaction?

The reaction rate usually increases until it reaches a maximum velocity.

How does enzyme concentration affect the rate of an enzyme catalyzed reaction?

Typically increases the reaction rate, provided there is sufficient substrate available.

How does temperature affect the rate of an enzyme catalyzed reaction?

Can denaturing enzymes and reduce activity.

How does pH affect the rate of an enzyme catalyzed reaction?

Can alter the enzyme's structure and function, affecting its activity.

What is competitive inhibition?

A process where an inhibitor competes with the substrate for the active site of an enzyme, reducing the rate of reaction.

What is noncompetitive inhibition?

Inhibition where the inhibitor binds to an enzyme at a site other than the active site, reducing its activity without competing with the substrate.

Does noncompetitive inhibition or competitive inhibition get overcome by additional substrate?

Competitive inhibition.

How does feedback inhibition regulate the abundance of a given biomolecule?

By utilizing the end product of a metabolic pathway to inhibit an upstream process, thereby balancing production and preventing excess accumulation.

What are three ways that cells localize their enzymes for more efficient functioning in metabolic pathways?

Organelle compartmentalization, in membrane proteins, and in mutli-enzyme complexes.