Ch. 8: An Intro to Metabolism

cellular respiration

process of extracting energy stored in sugars and other fuels

metabolism

the totality of an organism’s chemical rxns

metabolic pathway

a series of chemical reactions that either builds a complex molecule or breaks down a complex molecule into simpler compounds

catabolic pathways

-breakdown pathways

-release of energy by breaking down complex molecules

anabolic pathways

-consume energy to build complicated molecules from simpler ones

-also called biosynthetic paths

EX) protein synthesis from amino acids

energy

the capacity to cause change; a rearrangement of a collection of matter

kinetic energy

the energy associated with the relative motion of objects

potential energy

energy that is not kinetic;

energy that matter possesses due to its location or structure

EX) water behind a dam

heat

a form of thermal energy. it is kinetic associated with random movement of atoms or molecules.

chemical energy

potential energy available for release in a chemical reaction

thermodynamics

the study of energy transformation that occur in a collection of matter

First law of thermodynamics

energy can be transferred or transformed, but it cannot be created or destroyed.

Second law of thermodynamics

states that due to a loss of usable energy during energy transfer, that things in the universe tend to go into etophy. (randomness/disorder)

exergonic rxn

proceeds with a net release of energy and occurs spontaneously.

-aka. catabolic

-🔼G

endergonic rxn

the one that absorbs free energy from its surroundings.

-NOT spontaneous; ENERGY is required to drive the rxn

-aka. anabolic

+🔼G

3 types of work that a cell does

chemical, transport, and mechanical work

chemical work for a cell

pushing reactions which would not occur spontaneously

(synthesis of polymers from monomers)

transport work for a cell

pumping of substances across membranes against the direction of spontaneous movement

mechanical work for a cell

the beating of cilia or contraction of a muscle cell

energy coupling

the use of an exergonic process to drive an endergonic one

ATP is….

adenosine triphosphate

ATP sugar

ribose

ATP’s nitrogenous base

adenine

ATP has a chain of…

3 phosphate groups

What 3 things make up ATP?

1. sugar = ribose

2. nitrogenous base = adenine

3. chain of = 3 phosphate groups

Bonds between phosphate groups of ATP can be _________ by adding water. This releases energy.

hydrolyzed

Coupling (rxns)

when two rxns can be coupled so that overall, the coupled rxns are exergonic.

-transfer of a phosphate from ATP to another molecule.

*recipient = phosphorylated

In coupling, the recipient of the phosphate group is said to be ________.

phosphorylated

ATP cycle

the shuttling of inorganic phosphate and energy

Enzymes

-macromolecule proteins that act as a catalyst

Catalyst

a chemical agent that speeds up a reaction without being consumed by the reaction itself

Activation Energy/Energy of Activation

the initial investment of energy for starting a reaction.

-the energy required to contort the reactant molecules so the bonds can break

An enzyme catalyzes (speeds up) a reaction by lowering the ________ _________.

activation energy

When an enzyme catalyzes a rxn by lowering the activation energy, what does this allow?

it allows the reactant molecules to absorb enough energy to reach transition state even at a moderate temperature

Enzymes cannot make reactions occur that would not normally occur. They just ______ those that would anyway.

hasten (speed up)

substrate

the reactant an enzyme acts on

the enzyme binds to the substrate to form an _____-______ complex.

exzyme-substrate

active site

a restricted area of an enzyme molecule where the enzyme molecule actually binds to the substrate

How does temperature affect enzyme activity

Enzyme activity generally increases with temperature up to a certain point and then decreases significantly if the temperature exceeds the enzyme's optimal range, leading to denaturation.

How does pH affect enzyme activity

Enzyme activity is highly dependent on pH levels, as each enzyme has an optimal pH range where it performs best. Going outside this range can lead to decreased activity or denaturation.

Cofactors

nonprotein helpers that many enzymes require for catalytic activity

If a cofactor is an organic molecule, it called a _________.

coenzyme

2 types of enzyme inhibitors

competitive and noncompetitive inhibitors

competitive enzyme inhibitors

molecules that mimic the substrate and reduces productivity of enzymes by blocking substrates from entering the active site

noncompetitive enzyme inhibitors

molecules that impede enzymatic reactions by binding to another part of the enzyme.

-this causes the enzyme to change shape in a way that the active site becomes less effective.

True or false: ATP + water causes a release of energy

true. its hydrolysis

Energy coupling would occur between ATP whose delta G is - 7.3 kcal/mol and an equation whose delta G is

4.9+ (as long as the total delta G is negative to drive an endergonic rxn)