Unit 5 Cellular Energy
Name_____________________________________________ Quiz Date ____________
Test Date __________
I. Enzymes (159)
There are countless numbers of chemical reactions occurring in every cell all the time. Virtually all of these reactions
require the action of _________________, catalytic _______________. A catalyst ___________________ a
chemical reaction without being ___________________________________. An enzyme works by lowering the
activation energy, that is the energy required to ______________________________________________.
Enzymes share four common features:
A. Enzymes work best within a narrow _____ and _______________ range. This is because of the importance of the
____________ or ____________________ of the enzyme. When the pH or temperature is altered, the
_______________________ and interactions are also changed, changing the shape of the enzyme.
B. Enzymes do not make a reaction happen that couldn’t happen on its own; they simply make the reaction occur much
________________.
C. Enzymes are not _________________________________. The same enzyme may be used over and over again.
D. Enzymes are ________________________. The substrate is the ______________________. The substrate
fits into a portion of the enzyme called the _________________. As the substrate fills the active site, this leads
to a phenomenon known as ___________________, almost like a __________________. It is this induced fit
that is responsible for lowering the _____________________________ of the reaction.
II. Metabolism (218-221)
A. All chemical reactions in a cell are referred to as cell ______________________
B. Metabolic pathways- series of chemical reactions in which
the ____________ of one reaction is the _______________
for the next reactions. 2 Types:
a. Catabolic pathways- ____________________ by
breaking down larger molecules into smaller
molecules
EX. Cellular Respiration- ___________ molecules
broken down to release __________ for cell to use.
b. Anabolic pathways- use the energy released by
catabolic pathways ___________________
molecules from ________________ molecules.
EX. Photosynthesis- ___________________ from
Sun is _________________ to ________________
in form of glucose.
c. The relationship of anabolic & catabolic pathways
results in the ____________________________
within an organism as well as within an ecosystem.
III. CHEMICAL ENERGY AND LIFE (pp. 218-221)
A. Energy and Life
Energy is the ___________________. Cells require energy for _____________ reactions, ___________ transport,
___________________, and maintaining _________________. We obtain energy from _______, but most energy
originally comes from the sun. Plants are able to capture the sun’s energy and use it to produce glucose,
__________. This process, known as ___________________, occurs in the __________________ of plant cells.
The reaction for photosynthesis is:
___________________________________________
Plants and other organisms that can make their own food are known as __________________. Humans and
other organisms that have to obtain food are known as ____________________. Although glucose
is the preferred energy molecule for the cell, other ___________________, ___________, and _____________ can
also be broken down for energy.
B. Chemical Energy
The chemical energy in food (and all molecules) is stored in the ____________________________. This is
_________________ energy. When the bonds are broken and the ___________________ are released,
some energy is lost as _________, but a percentage of the potential energy can be converted to useable energy in
the form of ___________. Food molecules cannot be used as a direct energy source for the cell because food
contains too much energy ... if it were released all at once, it would be __________________ and______________.
C. ATP
__________________________ is a ____________________
that is composed of:
 ______________- nitrogen base
 _____________- 5 carbon sugar
 _______________________________
Energy is stored in ____________________________________.
These “rechargeable batteries” are mostly present
in the cell in two forms:
 ATP - Adenosine Triphosphate. Has 3phosphate groups.
 ADP - Adenosine Diphosphate. Has 2 phosphate groups.
 _______ has the most phosphate bonds, and therefore contains the most ______________ or stored energy.
 Cells are able to use and recycle ATP by breaking off or adding a ___________________ group.
1. Energy can be used when a ___________________ bond is ________________.
_____________________________________
2. Energy is stored; that is, ATP is “recharged” by ______________ a phosphate group to _____________
_____________________________________
*Under normal conditions, _______________ of these processes are occurring at the _____________________ and
______________________________in a cell*
II. PHOTOSYNTHESIS (222-227)
Research into _____________________________________began centuries ago with this simple question: When a
tiny seed grows into a huge plant, where does all the “new plant” come from?
A. Scientists discovered that in the presence of ________________________, plants transform ____, and water into
carbohydrates and release ___________________________.
_______________________+__________________________LIGHT_____________________+___________________
_______________________+__________________________LIGHT_____________________+___________________
 In addition to water and ___________________, _____________________ and ________________ are needed for
photosynthesis to happen.
B. Chloroplast
1. Found mainly in the ____________________ of most plants
2. Disk-shaped organelles contain 2 main compartments
a. Thylakoids- flattened ___________________________ that are arranged in stacks, this is where the
light-dependent rxn take place here.
b. Grana- stacks of ______________________
c. Stroma- __________________________ that is outside the _____________, this is where lightindependent rxn takes place
C. Pigments- light ___________________colored molecules
1. Found in _______________ membranes
2. Different pigments absorb specific __________________ of light
a. ____________________- _______________most strongly in the _________________ region of the visible
light spectrum & _______________ light in the ___________ region of the spectrum. (Why leaves appears
green to our eyes) More abundant than other pigments in leaves, thus hides the colors of the other
pigments. Different types called __________________________
b. Accessory pigments- allows plant to ___________ different ______________________ of light energy
 ___________________- _______________in ______________________region &________________,
______________________ Ex. β – carotene
 In fall production of ____________________slows down or stops, thus bringing out the colors of the
accessory pigments.
ENERGY & ELECTRONS When ________________ absorbs light, the energy is ____________________ to electrons in
the chlorophyll ________________________. HIGH ENERGY _________________________ make photosynthesis work!
REACTIONS OF PHOTOSYNTHESIS
 PHOTOSYNTHESIS HAPPENS IN CHLOROPLASTS: Proteins that are part of the thylakoid membrane organize
__________________________________into clusters called ______________________________.
 LIVING THINGS NEED ENERGY CARRIERS: Molecule that carries energy =_______________. Molecule that carries
HIGH ENERGY ELECTRONS=__________________, is one of the carriers that cells use to transport high energy
electrons.
______________+_____+______--> _________________
 LIGHT DEPENDENT REACTION: Requires _____________. Molecules are part of____________________
membranes and made up of _____________________________________connected by
_________________________ and ___________________________. Uses light energy to change ADP +
P__________________ and ______________+_____+ NADPH. Breaks apart ______ molecules and releases
_________________________.
 CALVIN CYCLE: (also called ____________________________________reaction). Does
___________require______. Happens in the _______________ between the thylakoids. ______________donates
________________+________________. ATP donates _______________ and ____ donates
__________________&_____________ to make _______________________.
 FACTORS THAT AFFECT PHOTOSYNTHESIS:
_____________________________________:Water is one of the raw materials needed, so a shortage of water can
__________or__________ photosynthesis. EX:
______________________________________:Photosynthesis enzymes function best between
_________________.At ____________________________above or below this range, photosynthesis will
______________or_______________. EX:
Light _________________________More light increases rate of photosynthesis up to a certain level until plant reaches
its _______________________________rate of photosynthesis.
PHOTOSYNTHESIS PROVIDES THE ______________________ WE BREATHE AND THE
_________________HETEROTROPHS (_________________) CONSUME TO SURVIVE.
_____________________+__________________light__________________+____________________
III. CELLULAR RESPIRATION – (228-232) ____________________________ ENERGY PRODUCTION
Cellular respiration is the breakdown of _______________________ in the presence of _________________ to “make”
___________. The oxygen required for cellular respiration is ___________ into the _________, __________ into the
____________, and is delivered to the __________________ of the body cells by ________________. The glucose
needed is obtained through ____________________. The glucose is transported in the blood and enters the body cells
via ___________________________________.
There are two major parts to cellular respiration:
A. Glycolysis – Means _______________________. Occurs in the ____________________ of the cell. Glycolysis
does not require ___________________. The splitting of glucose, or glycolysis, occurs very quickly with the aid of
_____________________, producing two _______-C molecules known as _________________________. In
addition, when the bonds of glucose are broken, the high energy electrons that are released are caught by
__________, a molecule that acts as an electron carrier. This electron energy will be converted to ATP later in the
process. Glycolysis requires __________ ATP to occur, but results in the formation of _________ ATP, for
a net ________________ of ________ ATP.
 Reaction: ______________________________________________________________________
 Net Energy Gain = _____________________
B. Oxidative Respiration – Glycolysis releases less than ¼ of the chemical energy stored in glucose. Most of its potential
energy remains bound in the _________________ formed from glycolysis. In aerobic conditions, meaning ____ is
available, the pyruvic acid formed from the breakdown of ___________________ during ___________________
enters the ____________________ of the cell where the _______________ of oxidative respiration complete the
breakdown of glucose to produce ________________, _________, and _______________.
 Reaction: _________________________________________________________________
Oxidative respiration is a 2-part process:
1. Krebs Cycle – Series of reactions that occur in the ___________________, in which the energy stored in
_________________ is released in the form of high-energy ________________ when bonds are broken
and pyruvic acid is completely broken down to _________. There are only ______ additional ATP produced in
the Krebs Cycle; most of the energy released is captured in the form of electron energy, producing additional
__________. In addition, a second type of electron carrier is utilized, producing 2 “filled” ____________.
 Net Energy Gain = _________________________________________________________________
2. Electron Transport Chain – In this step, the electron carriers, ___________ and ______________ “dump” their
electrons. These electrons are passed along a series of molecules embedded in the inner membrane of the
___________________ of ___________________ cells. This same process occurs in the __________________
of __________________ cells. As the electrons “fall” down the ETC, the energy they release is used to power an
enzyme known as ___________________________, which attaches phosphate groups to _________ to produce
_________. This process is known as _____________________________________________ because
_______________ must be present. It is the __________________________ of oxygen that “pulls” the electrons
down the ETC. As the electrons are collected by oxygen, ___________ is produced.

Net Energy Gain = ____________________
*Combined Reactions of Glycolysis + Oxidative Respiration (Krebs &ETC) = Cellular Respiration*
_____________________________________________________________________________
*Total ATP Yield Per Molecule of Glucose:*
Glycolysis =
Krebs Cycle =
ETC =
_________ ATP
_________ ATP
_________ ATP
V. FERMENTATION - _______________________ ENERGY PRODUCTION
Glycolysis is constantly occurring in the _____________ of every cell under _________________ conditions, meaning
___________________ is not required. The reaction for glycolysis is:
_______________________________________________________________________________________________
Glycolysis is the first step for all cellular energy production.
 If oxygen is available, _________________________________ follows glycolysis. Pyruvic acid is broken
down to __________________________________ and _______ ATP are produced.
 If oxygen is not available, some types of cells have a back-up mechanism for glucose metabolism
called ______________________. If a cell cannot switch to fermentation, it cannot survive without oxygen.
o Cells that can carry out cellular respiration and fermentation are known as
_______________________ ______________________.
o Cells that cannot switch to fermentation are known as
______________________________________.
A. General Description
In fermentation, the pyruvic acid formed during glycolysis does not enter the _______________________, instead,
the entire pathway takes place in the ________________. Fermentation does not produce any additional
_____________, but the removal of ______________________ from the cytosol allows the process of
glycolysis and the net gain of _______ ATP to continue.
B. Types of Fermentation - The 2 most common fermentation pathways used by cells are:
1. Lactic Acid Fermentation – Pyruvic acid is converted to __________________.
May be utilized by:
 Human Muscle Cells – Occurs when demand on muscles exceeds supply of oxygen. As lactic acid
builds up in the muscle cells, it is felt as ______________________. This is referred to as
________________. As activity slows, and oxygen is re-supplied, the muscle cells switch back to
_______________________ and the lactic acid is sent to the _______________________ to be broken
down.
 Bacteria & Fungi – There are some types of bacteria & fungi that carry out lactic acid fermentation in
_______________________ conditions. This is utilized by the dairy industry to produce ___________
and ________________________.
 ______________________________________________________________________________
2. Alcoholic Fermentation – Pyruvic acid is converted to ________ ________ and _________. When oxygen
supplies are depleted, ____________ and many bacteria switch to alcoholic fermentation. This process is used
commercially for ____________________________________
 ______________________________________________________________________________
**TOTAL ATP GAIN IN FERMENTATION = ________ ATP **