Biology
Ch. 6 Cellular Respiration
Notes
Glycolysis: “Glucose splits”
6C + 2ATP + NAD+  2-3C + 4ATP + NADH
LT3d
6.14 Describe the evolutionary history of glycolysis. These are three lines
of evidence that leads scientists to think that glycolysis is an ancient
process.

It is universal: Glycolysis exists in nearly all organisms- it evolved
early and was passed down

Occurs in cytoplasm therefore does not require membrane-bound
organelles, eukaryotes evolved 1 billion years after prokaryotes

For nearly 1 billion years, when the early Earth had no free oxygen in
the atmosphere, prokaryotes used glycolysis to make ATP because it
does not need oxygen.

Metabolic “heirloom” still functions in fermentation and first step in
cellular respiration.
The fate of pyruvate is determined by the presence or
absence of O2.
In the absence of O2
6.13
Compare the reactants, products, and energy yield of alcohol and lactic acid
fermentation.
The purpose of fermentation is to regenerate the electron acceptor NAD+. Without it,
glycolysis can not continue because there is no place to put its electrons. It is NOT the
purpose of fermentation to produce alcohol or lactic acid. These are simply byproducts.

Fermentation = Anaerobic (without O2) Respiration
The pathway followed is determined by the species type
.
Alcohol Fermentation (yeast)
Lactic Acid Fermentation (muscle)
Glucose (6C)  2 Pyruvate (2 x 3C)
Glucose (6C)  2 Pyruvate (2 x 3C)
2 Lactate (2 x 3C) + 2 ATP
2 Ethanol (2 x 2C) + 2 CO2 + 2 ATP
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In the presence of O2
When Oxygen is present, pyruvate will be sent into the mitochondrion.
C6H12O6 + 6 O2  6 CO2 + 6H2O + energy
6.7–6.12 Compare the energy yield of the three stages of cellular respiration.
Reactants
Products
1. Glycolysis
Glucose
2. Citric Acid
Cycle
2 Pyruvate 
2 Acetyl CoA +
2 CO2
3. Oxid.
Phosph.
Oxygen
12 NADH
2 FADH2
2 Pyruvate
2 NADH
2 ATP
(2 NADH)
6 NADH
2 FADH2
2 ATP
2 CO2
34 ATP
Energy Yield
in # of ATP
2
2
34
total = 38 ATP
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Comparing Photosynthesis and Cellular Respiration
How ATP is made
Electron Transport Chain (ETC and ATP Synthase)

The electron transport chain is used to take the high-energy
electrons (stripped from sugar or captured from chlorophyll-a) to
move H+.

The proteins of the chain (gray wheels in the image) must be
embedded in a membrane.

Once the electrons are used in the ETC, they are
(at the ground state again in cellular respiration and
excited a second time in photosynthesis)
Cellular Respiration:
The spent electrons are taken up by oxygen and, along with H +, make
water. This explains our need for oxygen and the production of
water in the equation.
Many poisons exert their effect here. Potassium Cyanide (used in
gas chamber during WWII), for example, blocks the passage of
electrons to oxygen thus causing the electrons in the ETC to
back up, H+ are not moved, the gradient is lost, and no ATP
can be made.
Photosynthesis:

The first time electrons are energized (excited),
they are used to make ATP using an ETC.

The second time they are energized, they are
captured by NADP+ as NADPH.

ATP is used as the Ea to make glucose

Energized electrons, carried by NADPH, are put
into the sugar along with the H+ it picked up.
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Nice to know
6.2
Describe and compare the processes of breathing and cellular
respiration.

Breathing: moving air in and out of a body to get oxygen and expel
carbon dioxide.

Cellular Respiration: aerobic (with O2) harvesting of energy from
food molecules by cells.
6.4
Explain how the human body uses its daily supply of ATP.
Minimum functions (maintenance) = 75% of calories taken in each day
Voluntary Activity = varies according to activity
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Review
6.3
Provide the overall chemical equation for cellular respiration. Compare the efficiency of this process in cells to the
efficiency of a gasoline automobile engine.
C6H12O6 + 6 O2  6 CO2 + 6H2O + energy

40% of the energy in 1 glucose is converted into the chemical energy of 38 ATP.

25% of the energy in gasoline is converted to kinetic energy.

Organisms: green plants, algae, photosynthetic protists & bacteria
Life is solar-powered because the energy for all life comes from the sun and is converted from radiant energy to chemical
energy by chlorophyll.
Stages of Cellular Respiration and Fermentation
6.6
List the cellular regions where glycolysis, the citric acid cycle, and oxidative phosphorylation occur.
Glycolysis
Citric acid
cycle
Oxidative
phosphorylation
Location
cytoplasm
matrix of
mitochondion
across the
inner
membrane
LT3a Use the diagram to identify

the overall goal of cellular respiration. (Circle the answer)

the organelle in which it occurs (write it in big letters above the figure.)

the three main stages of cell respiration (Name each process in the correct box in the picture. Number them in
order: 1, 2, 3.)
LT3d Use the diagram to identify

the overall goal of glycolysis
(use an exclamation point
after it!)

where it occurs in the cell
(add a label)
LT3d Use the diagram to identify

add a box for fermentation
and label it as such.

Choose either lactic acid or
alcohol fermentation and
use arrows to show where it
forms.

the overall goal of
fermentation in relation to
glycolysis.
LT3b,d
Use the diagram to identify the
beginning and ending products
for each of the three stages of
glycolysis and cellular respiration.
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LT3d Explain three lines of evidence that leads scientists to think that glycolysis is an ancient process?
Universal: all organisms use it
therefore it evolved very early and
was passed down.
Does not require oxygen; early Earth
had no oxygen.
Does not require cell organelles; first
life, prokaryotic cells, could use it for
energy.
LT4a Explain the similarities and differences between glycolysis, cell respiration and photosynthesis.
6.1
Compare the processes and locations of glycolysis, cellular respiration and photosynthesis.
Glycolysis:

Process: Break down glucose into 2-3C molecules + ATP + NADH

Location: Cytoplasm

Organisms: all
Cellular Respiration:

Process: breaks down glucose in the presence of oxygen to produce ATP for cellular work.

Location: mitochondria

Organisms: all eukaryotic cells
Photosynthesis:

Process: builds glucose from CO2 and H2O using the energy from the sun.

Locations: chloroplasts in eukaryotic

Organisms: plants, protists, (photosynthetic bacteria don’t use chloroplasts, only chlorophyll.
LT4a Use the table to list the similarities and differences between cell respiration and photosynthesis.
Photosynthesis Cellular Respiration
Name the site in the organelle
InterThylakoid
where energy conversion
membrane
Space
reactions occur.
Space
Name the site in the organelle
Stroma
Matrix
that deals with carbon molecules.
Name the membrane that
separates the two spaces and is
Thylakoid
Inner
the site where enzymes (that
Membrane
Membrane
catalyze the process) are
embedded.
LT4a Use the diagram to help you explain the
similarities between cell respiration and photosynthesis.
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