Chapter 6 Flashcards
cells obtain energy from ______ using _______ and apply the energy to ______
sugar, cellular respiration, perform work
metabolism
totality of an organism’s chemical reactions
metabolism is an emergent property that arises from?
orderly interactions between molecules
metabolic pathway
begins with specific molecules and ends with a product
each step of the metabolic pathway is?
catalyzed by a specific enzyme
catabolic pathway
release energy by breaking complex molecules into simpler compounds.
anabolic pathway
consume energy to build complex molecules from simpler ones.
anabolic pathway is also called?
biosynthetic pathway
bioenergentics
study of how energy flows through living organisms.
energy
capacity to cause change
work is the movement of?
matter against opposing forces
thermal energy
kinetic energy associated with random movement of molecules.
heat
thermal energy in transfer from one object to another
chemical energy
potential energy available for release in a chemical reaction
thermodynamics
study of energy transformations
Organisms are ____ systems
open
first law of thermodynamics
energy cannot be created or destroyed
the first law of thermodynamics is also called?
principle of conservation of energy
second law of thermodynamics
every energy transformation increases entropy of the universe
heat ____ the disorder of the surroundings
increases
scientists use the term disorder to? (2)
-show how dispersed energy is in a system
-show how many energy levels are present
spontaneous process occurs without?
energy input
For a process to occur spontaneously it must?
increase the entropy of the universe
Individual cells and whole organisms create?
ordered structures from disorganized starting materiel
free energy
portion of a system’s energy that can do work when temp and pressure are constant.
A process is spontaneous and can perform work only?
when it is moving towards equilibrium
exergonic reaction
proceeds with release of free energy
exergonic reaction is ________ and Delta g is _____?
spontaneous, -
endergonic reaction
absorbs free energy from its surroundings
endergonic reaction is _______ and Delta g is _____?
nonspontaneous, +
the magnitude of Delta g is?
the quantity of energy required to drive a reaction
Reactions in an isolated system eventually?
reach equilibrium and can do no work.
One of the defining features of life
metabolism as a whole is never at equilibrium
What prevents a system from reaching equilibrium?
the product of each reaction is the reactant for the next.
A cell does 3 main kinds of work.
-chemical
-transport
-mechanical
energy coupling
the use of an exergonic process to drive an endergonic one
Most energy coupling in cells is mediated by?
ATP
ATP (adenosine triphosphate) is composed of
ribose, adenine,and a chain of 3 phosphate groups
the bonds between the phosphate groups of ATP can be broken by?
hydrolysis
ATP hydrolysis releases?
energy, ADP, and inorganic phosphate
the energy released during ATP hydrolysis comes from?
chemical changes to a state of lower free energy
Why does ATP hydrolysis releases so much energy?
there is a repulsive force from the 3 negatively charged phosphate groups.
The triphosphate tail of ATP is the chemical equivalent to?
compressed spring
the chemical work in a cell is powered by?
ATP hydrolysis
ATP drives endergonic reactions by?
phosphorylation
Phosphorylation
transferring a phosphate group to another molecule
The recipient molecule from phosphorylation is called?
phosphorylated intermediate
Overall the coupled reactions in ATP hydrolysis are?
exergonic
ATP hydrolysis leads to? (2)
-change in proteins shape
-affects its ability to bond to other molecules
The energy to phosphorylate ADP comes from?
catabolic reactions in the cell
catalyst
speeds up a reaction without being consumed
enzyme
macromolecule that acts as a catalyst
most enzymes are ___?
proteins
Activation energy
energy required to start a reaction by breaking bonds
Instead of relying on heat, organisms carry out _____ to speed up reactions.
catalysis
Enzymes do not affect?
the change in free energy (Delta G)
Enzymes are ____ for the reactions they catalyze?
specific
substrate
reactant molecule on which an enzyme acts
Most enzymes names end in?
ase
active site
region that the substrate binds to the enzyme
Enzyme specificity results from the fit between?
the shape of the active site and substrate
Induced fit
substrate binds to an active site and both change shape slightly, creating an ideal fit for catalysis
Substrates are held to an enzyme’s active site by?
weak interactions
example of weak interactions
hydrogen bonds
Saturated Enzyme
All enzyme molecules in a solution are bonded with substrate.
an enzymes activity can be affected by? (2)
-temperature and pH
-chemicals that influence the enzyme
Each enzyme has a ______ and ______ at which the reaction rate is the greatest.
optimal temperature, pH
Cofactors
carry out processes difficult for amino acids
Cofactors are _____ molecules.
non protein
Coenzyme
organic cofactor
What often act as coenzymes or the raw material coenzymes are made out of?
vitamins
competitive inhibitor
binds to the active site and prevents substrate from binding
noncompetitive inhibitor
binds to an alternate site causing the active site to change shape.
Irreversible enzyme inhibitor examples
poison and toxin
under certain circumstances an altered __ might be favorable.
enzyme
Allosteric regulation
inhibit or stimulate an enzyme’s activity
allosteric regulation occurs when
a regulatory molecule binds to a protein at one site but affects the proteins function at another site.
the enzyme complex oscillates between?
active and inactive shapes
binding of an activator molecule ___ the active shape.
stabilizes
cooperativity
binding of one substrate molecule to the active site of one sub unit locking the other sub units in shape
feedback inhibition
end product of a metabolic pathway shuts down the pathway
feedback inhibition prevents a cell from ______ by _______
wasting chemical energy, synthesizing more product than is needed
