AP BIOLOGY
Chapter 8
Metabolism
The FIRST
_____ Law of Thermodynamics
states that energy can be transformed
and transferred by NEVER created or
destroyed
Anabolic pathways
→ consume energy to build molecules
release energy by breaking down molecules
The measure of disorder or randomness
(symbolized by S) entropy
The SECOND
_______ Law of Thermodynamics
states that every energy transfer or
transformation increases the entropy
of the universe.
Chemical reactions with a NEGATIVE
free energy (- Δ G) are ____________
exergonic
endergonic
exergonic
Chemical reactions with a POSITIVE
endergonic
free energy (+ Δ G) are ____________
endergonic
exergonic
Most enzymes belong to which group
of macromolecules? proteins
Molecules that speed up chemical
catalysts
reactions are called ____________
Energy associated with moving objects is
called _______
kinetic energy
Catabolic pathways
consume energy to build molecules
→ release energy by breaking down molecules
potential
Chemical energy is a form of ___________
energy
kinetic potential
Reactions that release free energy
exergonic
are called ______________
exergonic
endergonic
negative
The hydrolysis of ATP is a ________ ΔG
reaction.
Catalytic proteins that speed up chemical
reactions in living things are called
enzymes
____________
Reactions that absorb free energy
endergonic
are called ______________
exergonic
endergonic
Chemical reactions with a NEGATIVE
free energy (- Δ G) are ____________
spontaneous
spontaneous
nonspontaneous
Region on an enzyme where regulatory
Allosteric site
molecules can bind = ______________
Chemical reactions with a POSITIVE
nonspontaneous
free energy (+ Δ G) are ____________
spontaneous nonspontaneous
The initial investment of energy for
starting a chemical reaction is called
Activation energy OR
the _______________
Energy of activation
The place on an enzyme where the
active site
substrate attaches = _____________
Chemical reactions with a NEGATIVE
spontaneous
free energy (- Δ G) are ____________
spontaneous nonspontaneous
Which kinds of bonds hold the substrate
to the active site of an enzyme?
Weak interactions like hydrogen & ionic bonds
Nonprotein “helpers” for catalytic activty
cofactors
are called ______________
If a cofactor is an organic molecule it
coenzyme
is called a ____________
Which kind of food molecules often
act as coenzymes?
vitamins
A molecule that mimics a substrate,
binds to the active site, and reduces
the activity of an enzyme is called
COMPETITIVE
a(n) _______________
inhibitor.
NONCOMPETITIVE inhibitors slow down
______________
enzymatic reactions by binding to a
site other than the active site and
causing a change in the enzyme’s shape
FEEDBACK
In ___________
inhibition, a metabolic
pathway is switched off by the binding
of its end product.
The change in the shape of the active
site of an enzyme after the substrate
attaches so that it binds more snugly
INDUCED FIT
is called _____________
When the binding of one substrate
molecule primes an enzyme to accept
additional substrate molecules more
readily it is called COOPERATIVITY
______________
The arrow in the diagram is showing
ACTIVATION ENERGY of this
the _________________
reaction.
The arrow in the diagram is showing
CHANGE IN FREE ENERGY (ΔG) of
the ______________________
this reaction.
+ Δ G because
This reaction has a ___
the energy of the products is
greater then the reactants
-
This reaction has a ___ Δ G because
the energy of the products is less
then the reactants
How would adding an enzyme change the
graph of this reaction?
Enzymes lower the activation energy of
chemical reactions but don’t change the
energy of the products
Cells manage their energy resources by
using the energy from exergonic (-ΔG)
reactions to drive endergonic (+ΔG)
reactions in a process called
Energy coupling
____________________
ADP + Pi → ATP
+
This is a __ ΔG reaction.
Cellular respiration uses glucose, which
has a high level of free energy and
releases CO2 and H2O which have low
levels of free energy.
Is respiration spontaneous or not?
spontaneous
Is it exergonic or endergonic?
exergonic
How does the 2nd LAW of
thermodynamics help explain the
diffusion of a substance across a
membrane?
The 2nd Law is the tendency toward
randomness. Having equal concentrations on
both sides of a membrane is more random
than unequal concentrations. Diffusion from
high concentration to low INCREASES THE
ENTROPY as mandated by the 2nd law
If living things take simpler substances
and build them into complicated
systems (increase entropy), why does
this NOT VIOLATE the 2nd LAW of
thermodynamics ?
Living things are OPEN systems and must
constantly take in energy and materials
from outside to maintain the increase in
entropy