Bio 111: Metabolism

metabolism

all the chemical reactions that take place in cells

anabolic reactions

build molecules and require energy to occur

catabolic reactions

break down molecules and release energy

metabolic pathway

consists of many chemical reactions that require energy transformations

what is each step of a metabolic pathway?

a separate chemical reaction catalyzed by a specific enzyme

what is the relationship between each kind of metabolism

every kind of metabolism is connected

potential energy

energy stored due to an objects position, structure, or arrangement

kinetic energy

energy an object has because of its movement

thermodynamics

study of energy and energy transformations

system

matter being studied in thermodynamics

surroundings

everything outside the matter being studied in thermodynamics

open system

exchanges both energy and matter with its surroundings

what is an example of an open system?

humans

closed system

exchanges only energy with its surroundings

isolated system

exchanges neither matter nor energy with its surroundings

1st Law of Thermodynamics

states that energy can’t be created or destroyed

2nd Law of Thermodynamics

states that when energy is transfered or transformed, some energy is lost as heat

entropy

disorder

do cells have high or low entropy

low (they are highly organized, so they have low disorder and therefore low entropy)

what is the relationship between order and entropy?

as order increases, entropy decreases

Gibbs free energy (G)

energy from a chemical reaction available to do work after accounting for entropy

delta G

energy of the final state - energy of the initial state

what is the delta G for endergonic reactions

positive

what is the delta G for exergonic reactions?

negative

what kind of reactions are exergonic?

catabolic

what kinds of reactions are endergonic?

anabolic

are monomers or polymers more stable

polymers

what happens when ATP is dephsophorylated?

water is absorbed and energy is released

what happens when ATP is phosphorylated

energy is absorbed and water is released

phosphorylation

when a phosphate group is added

dephosphoralation

when a phosphate group is removed

which reactions are spontaneous/non-spontaneous

endergonic is nonspontaneous, exergonic is spontaneous

which reactions require/release energy

endergonic requires energy, exergonic releases energy

which reactions result in an increase/decrease in stability?

endergonic increases stability, exergonic decreases stability

which reactions require activation energy

endergonic and exergonic

which phosphate group on ATP is the closest to ribose? the middle? the farthest?

closest is Alpha, middle is beta, farthest is omega

is ATP stable or unstable? How is energy stored as a result

ATP is unstable, so energy is stored in more stable forms (like carbs and fats) so ATP does not disassociate and waste energy when its not needed

enzyme

molecule (typically protein) that catalyzes biochemical reactions

active site

region of enzyme where substrate binds and reaction occurs

allosteric site

different site on an enzyme where another molecule can bind and alter how the enzyme works

substrate

specific molecule an enzyme acts on; can be multiple depending on the reaction

how do enzymes catalyze biochemical reactions?

by lowering the activation energy

what do enzymes not do?

change the free energy of reactants or products, change delta G, change if a reaction is endergonic or exergonic, don’t get used up

what regulates which reactions occur and at what rate they occur in metabolic pathways?

enzymes

what are the environmental factors that impact enzyme activity?

pH, temperature, salt concentration

what are the physical location factors that impact enzyme activity?

which organism, tissue, or area of the cell the enzyme is in

regulatory molecules/cofactors/coenzymes

molecules that affect enzyme activity

examples of coenzymes

Fe2+, Mg2+, NAD+, FAD

inducers

regulatory molecules that increase enzyme activity by binding to the allosteric site

competitive inhibition

when an inhibitor binds to the active site to prevent the substrate from binding to the enzyme

noncompetitive/allosteric inhibition

when the inhibitor binds to the allosteric site to prevent the substrate from binding to the enzyme

allosteric regulation

when a molecule binds to the allosteric site to control the affinity of the enzyme for the substrate

what is the difference between a competitive inhibitor and a noncompetitive inhibitor

a competitive inhibitor temporarily decreases the rate of reaction, while a non-competitive inhibitor permanently decreases the rate of reaction