Chapter 8
Harvesting Energy:
Glycolysis and Cellular Respiration
Chapter 8 Outline
• 8.1 How Do Cells Obtain Energy?
• 8.2 How Is the Energy In Glucose Captured
During Glycolysis?
• 8.3 How Does Cellular Respiration Capture
Additional Glucose Energy From Glucose?
• 8.4 Putting It All Together
8.1 Photosynthesis
• Photosynthetic organisms capture the energy of
sunlight and store it in the form of glucose
• The overall equation for photosynthesis is:
Glucose
• Glucose is a key ____________ molecule:
– Nearly all cells metabolize glucose for energy
– Glucose metabolism is fairly simple
– Other organic molecules are converted to
glucose for energy harvesting
– During _______________, all cells release the
solar energy that was originally captured by
plants through ________________, and use it
to make ________
Overview of Glucose Breakdown
• The overall equation for the complete
breakdown of glucose is:
The main stages of glucose metabolism are:
–
Overview of Glucose
Breakdown
• Glycolysis
–
–
–
–
Occurs in the _________
Does _______________________
Breaks glucose into ______________
Yields ____ molecules of _____ per molecule of
glucose
Overview of
Glucose Breakdown
• If oxygen is absent
___________ occurs
– pyruvate is converted
into either _______, or
into_________and CO2
• If oxygen is present
__________________
occurs
Overview of Glucose Breakdown
• Cellular respiration
– Occurs in ____________
(in eukaryotes)
– Requires _____________
– Breaks down _________
into _______________
and _________
– Produces an additional __
____________ molecules,
depending on the cell type
8.2 Glycolysis
Overview of the two major phases of
glycolysis
1. Glucose ___________ phase
2. ____________________ phase
Glycolysis
1. Glucose activation phase
– Glucose molecule converted to highly reactive
___________________ by two enzyme-catalyzed
reactions, using ____________
Glycolysis
2. Energy harvesting phase
– Fructose bisphosphate is split into two threecarbon molecules of glyceraldehyde 3-phosphate
__________
– In a series of reactions, each G3P molecule is
converted into a _________, generating _______
per conversion, for a total of ________ ATPs
– Because two ATPs were used to activate the
glucose molecule there is a net gain of ____ ATPs
per glucose molecule
Glycolysis
2. Energy harvesting phase (continued)
– As each G3P is converted to __________, two
high-energy electrons and a hydrogen ion are
added to an “empty” electron-carrier ______
to make the high-energy electron-carrier
molecule ___________
– Because two G3P molecules are produced per
glucose molecule, _____ NADH carrier
molecules are formed
Glycolysis
•
Summary of glycolysis:
– Each molecule of glucose is broken down to
______ molecules of pyruvate
– A net of _______ molecules and __________
(high-energy electron carriers) are formed
Fermentation
•
•
Pyruvate is processed differently under
aerobic and anaerobic conditions
Under aerobic conditions, the high energy
electrons in NADH produced in glycolysis
are ferried to _____________reactions in
the _______________, making NAD+
available to recycle in glycolysis
Fermentation
•
•
Under anaerobic conditions, pyruvate is
converted into _________________, a
process called _____________
Fermentation does not produce more
_____, but is necessary to regenerate the
high-energy electron carrier molecule
______, which must be available for
glycolysis to continue
Fermentation
• Some cells ferment
pyruvate to form acids
• Human muscle cells can
perform fermentation
– ___________ conditions
produced when muscles
use up O2 faster than it
can be delivered (e.g.
while sprinting)
– ___________________
produced from pyruvate
Fermentation
• Some microbes
ferment pyruvate to
other acids (as seen in
making of cheese,
yogurt, sour cream)
• Some microbes
•
perform fermentation
exclusively (instead of
aerobic respiration)
Yeast cells perform
_______________
______________
Fermentation
•
•
•
Glucose is fermented to ________________
Sparkling wine is made by adding yeast with
the sugar in grapes; CO2 produces the fizz
Bread is made by adding yeast, sugar, and
flour; ______ bubbles cause the dough to
rise
8.3 Cellular Respiration
•
In eukaryotic cells, cellular
respiration occurs within
____________, organelles
with two membranes that
produce two compartments
– The _______________
encloses a central
compartment containing
the fluid ___________
– The outer membrane
surrounds the organelle,
producing an
______________space
Cellular Respiration
Overview of Aerobic Cellular
Respiration:
1. Glucose is first broken down
into pyruvate, through
____________, in the cell
cytoplasm
2. Pyruvate is transported into
the mitochondrion
(eukaryotes) and split into
____ and a ____________
group
Cellular Respiration
3. The acetyl group is further
broken down into CO2 in the
___________ (________
space) as electron carriers
are loaded
4. Electron carriers loaded up
in glycolysis and the Krebs
Cycle give up electrons to
the ___________________
_____ (ETC) along the inner
mitochondrial membrane
Cellular Respiration
5. A ___________________
produced by the ETC is used
to make ATP
_____________________
6. ATP is transported out of the
mitochondrion to provide
energy for cellular activities
Pyruvate Breakdown in Mitochondria
1. After glycolysis, pyruvate
diffuses into the
mitochondrion into the matrix
space
2. Pyruvate is split into ____ and
a 2-carbon _______ group,
generating __________ per
pyruvate
Pyruvate Breakdown in Mitochondria
3. Acetyl group is carried by a
helper molecule called
_____________, now called
Acetyl CoA
4. Acetyl CoA enters the Krebs
Cycle and is broken down into
_________
Pyruvate Breakdown in Mitochondria
5. Electron carriers _____
and _____ are loaded with
electrons to produce 3
_________________ per
Acetyl CoA
6. One ATP also made per
Acetyl CoA in the ______
__________
Electron Transport Chain
• Most of the energy in
glucose is stored in
electron carriers ______
_____________
– Only __ total ____
produced per glucose after
complete breakdown in the
Krebs Cycle
Electron Transport Chain
• NADH and FADH2 deposit
electrons into _______
_________________ in the
inner mitochondrial
membrane
• Electrons join with ______
gas and hydrogen ions to
made _____ at the end of the
_______
Chemiosmosis
1. Energy is released from
electrons as they are
passed down the
___________________
2. Released energy used
to pump _________
ions across the inner
membrane
–
Hydrogen ions
____________in
_____________ space
Chemiosmosis
3. Hydrogen ions form a
concentration gradient
across the membrane, a
form of stored energy
4. Hydrogen ions flow back
into the matrix through an
____________________
– Process is called
_________________
Chemiosmosis
5. Flow of hydrogen ions
provides energy to link _____
molecules of ADP with
phosphate, forming 32-34
_____
6. ATP then diffuses out of
mitochondrion and used for
energy-requiring activities in
the cell
8.4 Summary of Glucose Breakdown
• Figure 8-9
summarizes the
process of glucose
metabolism in a
eukaryotic cell with
________________…
Summary of Glucose Breakdown
• Figure 8-10, p. 143,
shows the energy
produced by each
stage of ________
___________
Influence on How Organisms Function
• Metabolic processes in cells are heavily
dependent on ATP generation (cyanide kills
by preventing this)
• Muscle cells switch between fermentation
and aerobic cell respiration depending on
__________________