Chapter 3: Energy, Catalysis, and Biosynthesis Flashcards
allows the cell to precisely control its metabolism
catalysis
the sum total of all the chemical reactions it needs to carry out to survive, grow, and reproduce.
metabolism
Two opposing streams of chemical reactions occur in cells:
- catabolic pathway
- anabolic pathway
The breakdown foodstuffs into smaller molecules, thereby generating both a useful form of energy for the cell and some of the small molecules that the cell needs as building blocks.
catabolic pathway (catabolism)
It uses the energy harnessed by catabolism to drive the synthesis of the many molecules that form the cell.
anabolic pathway (anabolism) or biosynthesis
The universal tendency of things to become disordered is expressed in a fundamental law of physics called the ________.
second law of thermodynamics.
This law states that in the universe as a whole, or in any isolated system (a collection of matter that is completely cut off from the rest of the universe), the degree of disorder can only increase.
second law of thermodynamics
systems will change spontaneously toward those arrangements that have the greatest probability.
second law
The measure of a system’s disorder.
entropy
the _________ the disorder, the ________ the entropy
greater - greater
What law expresses “ systems will change spontaneously toward arrangements with greater entropy”?
second law of thermodynamics
A cell is not an _________ system.
isolated
the chemical reactions inside a cell must increase the __________ of the entire system
total entropy
According to the ______________, energy cannot be created or destroyed—but it can be converted from one form to another
first law of thermodynamics
a product of energy conversion
heat
How does solar energy enter the living world?
through photosynthesis
a process that converts the electromagnetic energy in sunlight into chemical-bond energy in cells.
photosynthesis
Give examples of photosynthetic organisms:
plants, algae, and some bacteria
In the first stage of photosynthesis, energy from sunlight is captured and transiently stored as chemical-bond energy in specialized molecules called _________.
activated carriers
In the second stage of photosynthesis, the activated carriers are used to help drive a ___________ process.
carbon fixation
In this process, sugars are manufactured from carbon dioxide gas (CO2).
carbon fixation process
In plants and animals, the chemical energy is extracted from food molecules by a process of ________.
gradual oxidation or controlled burning
The Earth’s atmosphere is about how much oxygen?
21%
In the presence of oxygen, the most energetically stable form of carbon is ______ and that of hydrogen is ______.
CO2; H2O
The step-wise process by which food molecules are broken down to produce energy is known as cell respiration.
cell respiration
This means the addition of oxygen atoms to a molecule.
oxidation
involves the removal of electrons from an atom
oxidation
involves the addition of electrons to an atom
reduction
the acceleration of the specific chemical reactions needed to sustain life
catalysis
energy that must be acquired by a molecule to undergo a chemical reaction (for example a collision with other molecules)
activation energy
a substance that can lower activation energy
catalyst
the most effective catalyst
enzymes
_________ reactions are reductions
hydrogenation reactions
and the reverse ___________ are oxidations.
dehydrogenation reactions
energy that can be harnessed to do work or drive chemical reactions
free energy
Each enzyme binds tightly to one or two molecules, called ________.
substrates
A substance that can lower the activation energy of a reaction is termed a ______________.
catalyst
The useful energy in a system
free energy or G
it measures the amount of dis- order
ΔG
those that create disorder in the universe by decreasing the free energy of the system to which they belong;
Energetically favorable reactions
they have a negative ΔG
Energetically favorable reactions
they create order in the universe
Energetically unfavorable reactions
they have a positive ΔG
Energetically unfavorable reactions
___________ is increased when useful energy (harnessed) is dissipated as heat (useless).
Disorder
useful energy; can be harnessed and drive a chemical reaction
Free Energy / G
the difference in energy in reactant and product molecules
free energy chance / ∆G
The ratio of substrate to product at this equilibrium point
equilibrium constant, K
the energy released in the binding interaction
binding energy
the energy is stored as chemical-bond energy in a set of __________
activated carriers
energetically favorable reaction is used to drive an energetically unfavorable one, so that an activated carrier or some other useful molecule is produced.
coupled reaction
he wondered how energy is transformed during chemical reactions in cells.
Otto Meyerhof
a pioneer in the field of cell metabolism
Otto Meyerhof
He recognized that between its initial entry in the form of food and its final dissipation as heat, a large amount of energy must be made available by a series of interme- diate chemical steps that allow the cell or organism to maintain itself in a state of dynamic equilibrium.
Otto Meyerhof
He determined that working muscles give off heat, both as they contract and as they recover; further, he found that the amount of heat correlates with how hard the muscle is working.
Archibald “A.V.” Hill
The most important and versatile of the activated carriers in cells.
ATP (adenosine 5ʹ-triphosphate)
Any reaction that involves the transfer of a phosphate group to a molecule.
phosphorylation reaction.
the most abundant activated carrier in cells.
ATP
The ultimate source of energy for most living organisms
sun
release energy by breaking down organic molecules, including foods, through oxidative pathways.
Catabolic reactions
generate the many complex organic molecules needed by the cell, and they require an energy input.
anabolic reactions
catalyze reactions by binding to particular substrate molecules in a way that lowers the activation energy required for making and breaking specific covalent bonds.
Enzymes
govern all of the associations (and dissociations) that occur between macromolecules and small molecules in the cell.
Equilibrium constants
carries high-energy phosphate groups
ATP
carry high-energy electrons
NADH and NADPH
provide the carbon skeletons for the formation of macromolecules.
food molecules
