BIOL 101
STUDY GUIDE: ENERGY AND INFORMATION
6. Energy-Driven Inventions
6.1 Living Systems Require a Flow of Energy
In a phrase, how do physicists define “energy”? The ability to do work.
How would a cell biologist define “energy”? The ability to make specific changes occur.
The physicist’s definition of energy is not comprehensive enough for use in defining energy
changes within a living cell.
List five major sorts or categories of energy change within the cell. (a)'synthetic work is
demonstrated by the making of daughter cells from a parent cell,'(b)'movement is represented by
the streaming movement of the cytoplasm,'(c)'concentration of a substance within a cell is
effected by active transport,'(d)'electrical potential is generated by ion movement across a
membrane,'(e)'heat energy is generated by increasing the rate of respiration in the cell.
On a cold day, which of the following processes do your cells depend on to maintain an
operating temperature of 37 degrees Celsius?
a. shivering
b. muscle contraction
c. respiration energy production
d. metabolic heat generation
e. all of the above
Sometimes the cell pumps substances against diffusion forces that would carry those substances
the other way. What term would we give to this process? energy of concentration
6.2 Laws of Energy Flow in the Living World
Energy is freely convertible from one form to another but energy can never be created or
destroyed.
Systems that convert energy from one form to another are not 100% efficient, thus the amount of
useful energy decreases because some energy becomes useless, typically in the form of heat.
In nature, as energy freely changes from one form to another, the total amount of energy is lost.
In living things, energy conversion is inefficient, with much energy being lost in the form of
heat.
What form of energy do producers use when they set about to generate chemical energy—the
energy of C―H and C―O―H bonds. solar energy
Thus, a producer organism is called a “producer” because it produces usable chemical energy .
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BIOL 101
When your car engine burns the octane in gasoline, in what form does at least 50% of the energy
of the octane end up? heat energy
A lit match cannot continue to burn when the wood of the matchstick is consumed. This
statement illustrates what general law of energy flow? The law of conservation of matter and
energy.'
In a crowded, unventilated room, what causes the temperature to rise? Heat energy loss
6.3 Energy Flows in Chemical Reactions
Existing chemical bonds between atoms are broken and new ones are formed between different
atoms. In the broadest sense, this is the definition for a chemical reaction.
Give an example of a chemical reaction. Some bacteria'simply shuffle around atoms.
Whenever chemical bonds are broken, energy is required. Whenever chemical bonds form,
energy is given off.
Does an endergonic reaction require the input of energy, or does it give off energy? It must be
added in.
What term is given to the amount of energy required to break the bonds in reactant molecules?
activation energy
What is true of the bonds in reactant molecules that keeps most chemical reactions in nature from
occurring? Their bonds are lower than the activation energy necessary to break them.
When activation energy is not available for a given chemical reaction, the reaction will not go.
6.4 Enzymes Direct Energy Flow
How is the activation energy of desired reactions lowered in living things, so that the desired
reactions are able to go forward? By enzymes serving as an organic catalyst.
What words best describe the way in which enzymes bind to reactant molecules? selective shape
What exactly does an enzyme do the chemical bonds within the reactant molecule? Weakens
them
By binding to reactant molecules, what effect does an enzyme have on the activation energy for a
given reaction? An enzyme allows bonds in the reactant molecules to break freely.
6.5 Energy Flow in Reaction Pathways: Metabolism
What name do we give to sequences of chemical reactions within cells? metabolic pathways
In a (n) reactant the product of one reaction becomes the reactant of the next reaction and so on.
If the final end product of a metabolic pathway is continually removed and used elsewhere, then
the reactions of the entire pathway will be pulled in the direction of making more of the end
product.
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BIOL 101
Suppose an excess amount of product accumulates at the end of a metabolic pathway. The
product then binds to the allosteric site of the first enzyme along the pathway, shutting down the
pathway. What do we call this regulatory process? Feedback inhibition
An allosteric enzyme has a second binding site other than its own active site for converting
substrate to product. What does this second site bind to? The product of the last enzyme in the
pathway.
If the final product of a metabolic pathway begins to build up in excess, the pathway can often be
slowed down by a process called Feedback Inhibition.
A single regulatory molecule can shut down multiple metabolic pathways if it is able to add
phosphate groups that alter the active site of the first enzyme in each pathway.
6.6 Energy Pools in the Cell: ATP
Three phosphate groups linked to a ribose sugar which, in turn, is linked to a pyrimidine base
known as adenine: this phrase describes the structure of ATP (adenosine triphosphate) .
Where in the ATP molecule is the “high energy” bond that carries potential energy and is easily
broken? Last two phosphates
To derive energy from an ATP molecule, what bond must be broken? Phosphate bonds
Energy-releasing reactions drive biosynthetic ones forward by contributing to a pool of ATP
molecules.
The substance ATP would most likely enable a flagellum to drive a bacterium forward through
the medium in which it is swimming.
6.7 Energy Flow from Carbohydrates to ATP: Respiration
In respiration, chemical energy is transferred from glucose to ATP. The energy transfer,
however, is not 100% efficient. In the transfer, some of the energy is lost as heat. (Review
Section 6.2 above)
In what major cellular process are three interrelated, exergonic pathways and oxygen used to
generate large amounts of ATP from glucose molecules? aerobic respiration
The term aerobic respiration could be defined as about 30 individual, sequential chemical
reactions that form three metabolic pathways: one in the cytoplasm and two within the
mitochondrion.
List the reactants and products of the summary reaction for aerobic respiration. Reactants:
Glucose, oxygen, ADP Products: Carbon dioxide, water, ATP
Write out the summary reaction for aerobic respiration. 6Co2 + 6H2o + 36 ATP
Name the three stages of aerobic respiration. Glycolysis, Krebs Cycle, Electron Transfer
Phosphorylation
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The three metabolic pathways that make up aerobic respiration are really all parts of one larger
pathway because the products of early pathways (like NADH) become oxygen in the last one.
Aerobic Respiration: Stage 1 – Glycolysis
What is the first stage of aerobic respiration? glycolysis
In the process of glycolysis, one molecule of glucose is converted to two molecules of pyruvate.
Is carbon dioxide either a reactant in or product of glycolysis? Product of glycolysis.
Glycolysis is valuable to a cell because it produces ATP for driving biosynthetic processes.
Glycolysis is valuable to a cell because supplies minimal energy without requiring the presence
of oxygen as a reactant.
Glycolysis is valuable to a cell because it generates NADH that can be “cashed in” for ATPs
later.
Glycolysis is valuable to a cell because it produces pyruvate, which the Krebs cycle can further
degrade for more energy.
Aerobic Respiration: Stage 2 – The Krebs Cycle
All of the six carbon atoms in each glucose molecule leave respiration in the form of carbon
dioxide. Most of them leave during which part of aerobic respiration? Krebs Cycle
Which of the following is not a product of the Krebs cycle?
a. FADH2
b. carbon dioxide
c. ATP
d. NAD
e. NADH
The Krebs cycle’s NADH products are of value. In what way? They become more stable and
the electrons now on the NADH carrier molecules still contain considerable potential energy for
generating ATP molecules.
The most energetic and useful product of the Krebs cycle is NADH and FADH2 .
Aerobic Respiration: Stage 3 – Electron Transfer Phosphorylation
What is the immediate source of electrons for electron transfer phosphorylation? Substrates
around the Krebs cycle.
The final stage of aerobic respiration involves the phosphorylation of ADP to ATP by transfer of
electrons.
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During the electron transfer reactions, protons (H+ ions) are pumped (moved) to one side of the
inner membrane of the mitochondrion. The value of this pumping is that the resulting proton
gradient is then used to create an electrical potential which is relieved by an inward flow of
protons through the ATPase enzyme that phosphorylates ADP, generating ATP.
What is the most valuable product, energetically, of electron transfer phosphorylation? ATP
The value of the three stages of aerobic respiration is their ability to break down glucose, a single
molecule, with the resultant production of about 36 ATP molecules.
6.9 Energy Flow from Photons to Carbohydrates: Photosynthesis
________organisms build their own energy-rich molecules using solar energy.
Plants are considered autotrophic because their cells contain what critical molecule?
Name a process that uses chlorophyll molecules to produce high-energy carbohydrates.
List the reactants and products for the overall process of photosynthesis.
In photosynthesis, the H atoms used to make high-energy carbohydrates like glucose come from
which reactant molecule?
Photosynthesis: Stage 1 – Light-Dependent Reactions
The wavelengths of light used in photosynthesis are found in the _________ portion of the
electromagnetic spectrum.
Each wavelength of light has its own _______ level.
When light of the correct wavelength hits a photosynthetic pigment molecule, an electron within
one of its atoms becomes ________.
What is the value of accessory pigments within the chloroplast’s structure?
Accessory pigments and chlorophylls work together within the thylakoid membrane in clusters
called __________.
Photosystems harvest light energy and use it to transfer electrons to _________ molecules.
The light-dependent reaction is like the last stage of aerobic respiration in that both reaction
sequences carry out ________ _________ phosphorylations.
The light-dependent reaction is like the last stage of aerobic respiration in that both processes
generate the energy-rich _____ molecule.
The light-dependent reaction is like the last stage of aerobic respiration in that both processes
involve the flow of __________.
The light-dependent reaction is like the last stage of aerobic respiration in that both systems are
lodged within a ___________ surface.
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What is the role of NADPH in the process of photosynthesis? What does it carry? From where
to where?
NADPH is formed when it accepts high-energy __________ from an excited photosystem.
List three products of the light-dependent reaction.
Photosynthesis: Stage 2 – Light-Independent Reactions
In the chloroplast, light dependent reactions take place in the __________________ membrane,
while light independent reactions take place in the fluid of the ___________.
Where, within the chloroplast, are new molecules of glucose generated?
The immediate product of photosynthesis, three-carbon PGALs can be assembled together to
generate _______ molecules.
The immediate product of photosynthesis, three-carbon PGALs can also find their way into
_______ sugar molecules.
The immediate product of photosynthesis, three-carbon PGALs may eventually become part of
the subunits of ________ polymers.
The immediate product of photosynthesis, three-carbon PGALs are used to generate, transport,
and __________ forms of carbohydrates.
6.10 Energy Flow: An Integrated Picture
The overall process that uptakes energy-poor molecules (CO2 and H2O) from their reservoirs in
nature and converts them into energy-rich molecules is ___________.
What two processes complement each other within the global carbon cycle?
___________ organisms specialize in capturing energy.
___________ organisms are highly efficient at handling energy.
___________ organisms generate far more C―H bond energy than they themselves utilize.
7. Information and Its Expression in the Cell
7.1 The Need for Biological Information
Biological information must exist because cell structure is ________ enough to require
information for its construction.
7.2 The Nature of Biological Information
Who discovered DNA, and from what source did he isolate it?
What was the principle tool Rosalind Franklin used to unravel the structure of DNA?
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DNA contains two chains of nucleotides in which ______ and ______ alternate in supporting
each chain structurally.
Where in the DNA molecule’s structure is the genetic information located?
Where in the cell is DNA stored?
DNA is stored within in a partially condensed fiber called __________.
Griffith exposed weak living bacteria to just the fluids from heat-killed virulent bacteria. Some
of these weak bacteria became virulent and could now kill mice. What control experiment did he
do to argue that his weak bacteria changed to virulence in these studies? (select a choice from
below)
a. He grew his non-virulent bacteria for several years before infecting mice with them.
b. He injected viruses into his mice to test their resistance to viral infection.
c. He injected virulent bacteria into rabbits to see if they would die.
d. He injected heat-killed virulent bacterial fluids into a mouse to make sure the mouse would
survive.
e. He isolated two strains of bacteria and maintained them in colonies.
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