Biology Chapter 8: Metabolism

what is metabolism

the totality of an organism’s chemical reactions

what are some examples of these reactions

synthesizing and hydrolyzing macromolecules

how are reactions that make up cell metabolism characterized?

reactions that make up cell metabolism are complex, efficient, coordinated, and highly responsive to even the most subtle changes

what are metabolic pathways

metabolic pathways begin with specific molecules and end with a product

what are enzymes?

proteins that speed up chemical reactions

what are the two types of metabolic pathways?

anabolic and catabolic

what are catabolic pathways

breaking down complex molecules into simpler compounds

what is an example of a catabolic pathway

cellular respiration

what do catabolic pathways release

energy

what are anabolic pathways

reactions that build complex molecules from simpler molecules

what do anabolic pathways consume

energy

what is an example of an anabolic pathway

polymerization

what is energy

the capacity to cause change

cells transform energy…

from one form to another

what is kinetic energy

energy associated with the relative motion of objects

what is thermal energy

the random motion of atoms

what is potential energy

energy that matter processes due to its location or structure

what is heat

the transfer of thermal energy

what is chemical energy

the potential energy that can be released in a chemical reaction

what is thermodynamics

the study of energy transformations that occur in matter

what is an isolated system

a system unable to exchange energy and matter with its surroundings

what is an open system

a system that can exchange energy with its surroundings

what is an example of an open system

organisms

what is the first law of thermodynamics

energy can be transferred and transformed, not created, nor destroyed

what is the second law of thermodynamics

energy transfer/transformation increases the randomness (entropy) of the universe

what explains the second law of thermodynamics

the fact that energy is always lost as heat

cells, though highly ordered, convert organized energy into heat. this means that organizations…

does not decrease the unstoppable trend towards randomization

a synonym for entropy

randomness

cells create ordered structures from

less ordered materials

cells replace ordered forms with

less ordered forms

what is a spontaneous process

something that occurs without energy input

spontaneous processes increase

the entropy of the universe

non-spontaneous processes

occur without energy input

what is an example of a non spontaneous process

polymerization

what is an example of a spontaneous process

cellular respiration

how is spontaneity quantified

free energy

what is gibbs free energy

energy that can do useful work when temperature and pressure are uniform

as entropy increases, total energy _____________ and free energy ________

remains the same, decreases

in spontaneous processes, the change in G

is negative

in non-spontaneous processes, the change in G

is positive

spontaneous processes

release energy that can be harnessed to do work

in non-spontaneous process

energy is consumed and stored

free energy is a measure of

instability

spontaneous reactions increase

stability by decreasing a system’s free energy

as the cell moves towards equilibrium, it harnesses the energy of _______________

spontaneous processes

exergonic reactions

are spontaneous

endergonic reactions

are nonspontaneous

exergonic reactions release

free energy

endergonic reactions absorb

free energy

the more G released,

the more work can be done

the more G absorbed,

the more work needed to be done

what kind of reaction is this

exergonic reaction

a reaction that has a negative change in G is

exergonic

a reaction that has a positive change in G is

endergonic

what kind of reaction is this

endergonic

why is metabolic equilibrium equivalent to cell death?

it means the cell is not doing work, and thus, no energy flows into the system

organisms are

open systems

what is a defining feature of life?

metabolic disequilibrium

what is energy coupling

the use of an exergonic process to drive an endergonic reactions

what are the three main kinds of work that a cell does

chemical, transport, and mechanical

chemical reactions are usually

endergonic

what mediates most energy coupling

ATP

what is ATP composed of

ribose, adenine, and three phosphates

what is pictured here

ATP

what breaks down the bonds between phosphate groups

hydrolysis

what is released when the terminal phosphate bond is broken?

energy

where does this release of energy come from

the energy transformation NOT THE BONDS

why does ATP hydrolysis yield a lot of energy

triphosphate tails are particularly unstable

what’s going on here

ATP hydrolysis lols

what kind of work is powered by ATP hydrolysis

chemical work

ATP hydrolysis is

an exergonic reaction

ATP hydrolysis can drive

endergonic reactions

ATP drives endergonic reactions by

phosphorylation

what is phosphorylation

transferring a phosphate group

when a phosphate group is transferred, what is the recipient molecule called?

phosphorylated intermediate

ATP hydrolysis can also power

hydrolysis

what is going on in this image

ATP phosphorylates transport proteins

ATP hydrolysis can power which kind of protein?

motor proteins

what is ATP doing in this image

powering a motor protein

how is ATP regenerated

by adding a phosphate group to ADP

ATP regeneration is

an endergonic process

catabolic reactions

are exergonic processes

anabolic reactions

are endergonic processes

how do enzymes speed up metabolic reactions

they lower the energy barrier

what is a catalyst

a chemical agent that can speed up a reaction without being consumed by the reaction

chemical reactions involve

bond breaking and forming

what is activation energy

the initial energy needed to start a chemical reaction

how is activation energy usually supplied as

thermal energy absorbed from surroundings

how do enzymes catalyze reactions

they lower the activation energy barrier

do enzymes affect the change in free energy

no, they just speed up reactions that would occur eventualy

enzymes allow for ________ in reactions

specificity and control

what is a substrate

the reactant that an enzyme acts on

why are the reactions catalyzed so specific

because enzymes are proteins which are determined by a unique sequence of amino acids

what is the enzyme-substrate complex

where an enzyme binds to its substrate

what is A

substrate

what is B

active site

what is C

enzyme

what is the active site

the region where the substrate binds

binding alters

the enzyme’s shape

what is the alteration of the enzyme shape called

induced fit