Notes: Cellular Respiration
Chapter 4 section 4.4; 4.5 and 4.6
Chemical energy and food
• How much energy is in food?
– When 1 gram of glucose (C6H12O6) is burned
in the presence of oxygen, 3811 calories are
released.
• What is a calorie?
– A calorie is the amount of energy needed to
raise the temperature of 1 gram of water 1
degree Celsius.
Chemical energy and food
– On a food label
Calories (with a capital
“C”) represent
kilocalories. 1
kilocalorie = 1000
calories.
– Cells use the energy in
glucose by slowly
releasing it.
Chemical energy and food
• How many calories
are in 2 crackers?
60,000
• How many calories
are in 6 crackers?
180,000
• Cellular Respiration is the SLOW release
of energy from glucose.
4.4
Overview of Cellular Respiration
TEKS 4B, 9B
Cellular respiration makes ATP by breaking down sugars.
• Cellular respiration is aerobic, or requires oxygen.
• Aerobic stages take place in mitochondria.
mitochondrion
animal cell
Overview of Cellular Respiration
•
Is the process that releases energy by
breaking down glucose and other food
molecules in the presence of oxygen
within the mitochondria.
Oxygen + glucose  carbon dioxide + water + energy
O2
+ C6H12O6  CO2 + H2O + ATP
Glycolysis (part 1)
• Glycolysis is the process by which one
molecule of glucose is broken in half to
produce two 3-carbon molecules of
pyruvate (sometimes called pyruvic acid).
• Occurs within the cytoplasm.
4.5
Cellular Respiration in Detail
TEKS 4B, 9B
Glycolysis is needed for cellular respiration.
• The products of glycolysis enter cellular respiration when
oxygen is available.
– two ATP molecules are used to split glucose
– four ATP molecules are produced
– two molecules of NADH produced
– two molecules of pyruvate produced
4.4
Overview of Cellular Respiration
TEKS 4B, 9B
• Glycolysis must take place first.
–
–
–
–
anaerobic process (does not require oxygen)
takes place in cytoplasm
splits glucose into two three-carbon molecules
produces two ATP molecules and 2 NADH (NET)
Aerobic Cellular Respiration
If Oxygen is present
• The remaining 90% of the energy from the
glucose molecule that was not used in
glycolysis is used in the part of cellular
respiration that requires oxygen (aerobic).
• Cell Respiration occurs within the
mitochondria when oxygen is present.
• Also named aerobic respiration.
• There are two parts after glycolysis: the Krebs
Cycle and the Electron Transport Chain.
4.4
Overview of Cellular Respiration
TEKS 4B, 9B
Cellular respiration is like a mirror image of
photosynthesis.
• The Krebs cycle transfers energy to an electron
transport chain.
Krebs
1 Cycle
mitochondrion
ATP
– takes place in
matrix (area enclosed
and
by inner membrane) 6CO
mitochondrial matrix
2
– breaks down three-carbon
energy
molecules from glycolysis
2
3
– makes a small amount of
energy from
inner membrane
ATP
glycolysis
ATP
and
and
6H2 O
6O2
– releases carbon dioxide
– transfers energy-carrying
4
molecules
The Krebs Cycle
o Krebs Cycle (Citric Acid Cycle)- Pyruvate
is broken down into carbon dioxide
molecules in a series of steps that also
form ATP, NADH, and FADH2 for use in
the Electron Transport Chain.
o Occurs within the matrix
Play until 1:20
4.5
Cellular Respiration in Detail
The Krebs cycle is the first main part of cellular
respiration.
• Pyruvate is broken down
before the Krebs cycle.
– carbon dioxide
released
– NADH produced
– coenzyme A (CoA)
bonds to two-carbon
molecule
TEKS 4B, 9B
4.5
Cellular Respiration in Detail
TEKS 4B, 9B
• The Krebs cycle produces energy-carrying molecules.
4.5
Cellular Respiration in Detail
TEKS 4B, 9B
• The Krebs cycle produces energy-carrying molecules.
– NADH and FADH2 are made
– intermediate molecule with
CoA enters Krebs cycle
– citric acid
(six-carbon molecule)
is formed
– citric acid is broken down,
carbon dioxide is released,
and NADH is made
– five-carbon molecule is broken down, carbon dioxide is
released, NADH and ATP are made
– four-carbon molecule is rearranged
4.4
Overview of Cellular Respiration
TEKS 4B, 9B
• The electron transport chain produces a large amount of
ATP.
– takes place in inner
membrane
– energy transferred to
electron transport
chain
– oxygen enters
process
– ATP produced
– water released as a
waste product
1
mitochondrion
matrix (area enclosed
by inner membrane)
ATP
and
6CO2
energy
Electron Transport
3
energy from
glycolysis
and
6O2
2
inner membrane
ATP
and
6H2 O
4
In the Electron Transport Chain,
o Electron Transport Chain- Uses high energy
electrons from NADH and FADH2 from Krebs
cycle to build up H+ ions in the
Intermembrane space making it positive and
the matrix negative.
4.5
Cellular Respiration in Detail
TEKS 4B, 9B
The electron transport chain is the second main part of
cellular respiration.
• The electron transport chain uses NADH and FADH2 to
make ATP.
– high-energy electrons enter electron transport chain
– energy is used to transport hydrogen ions across the
inner membrane
– hydrogen ions
flow through a
channel in the
membrane
4.5
Cellular Respiration in Detail
TEKS 4B, 9B
The electron transport chain is the second main part of
cellular respiration.
• The electron transport chain uses NADH and FADH2 to
make ATP.
• The breakdown of one glucose molecule produces up to
38 molecules of ATP.
– ATP synthase
produces ATP
– oxygen picks up
electrons and
hydrogen ions
– water is
released as a
waste product
4.4
Overview of Cellular Respiration
TEKS 4B, 9B
• The equation for the overall process is:
C6H12O6 + 6O2  6CO2 + 6H2O
• The reactants in photosynthesis are the same as the
products of cellular respiration.
In the Electron Transport Chain,
o The H+ ions will then move through the ATP
synthase to the negative side causing the
ATP synthase to turn. Each turn brings ADP
and a phosphate (Pi) together to form high
energy ATP.
• The Krebs Cycle and Electron Transport
Chain occur in the mitochondria.
Fermentation
if no oxygen is present
•
•
•
Fermentation occurs when no oxygen is
present.
Also called anaerobic respiration meaning without oxygen.
It turns NADH back into NAD+ so that it
can be recycled and glycolysis can
continue.
4.6
Fermentation
TEKS 4B
Fermentation allows glycolysis to continue.
• Fermentation allows glycolysis to continue making ATP
when oxygen is unavailable.
• Fermentation is an anaerobic process.
– occurs when oxygen is not available for cellular
respiration
– does not produce ATP
4.6
Fermentation
TEKS 4B
• Fermentation allows glycolysis to continue making ATP
when oxygen is unavailable.
• NAD+ is recycled to glycolysis
• Lactic acid fermentation occurs in muscle cells.
– glycolysis splits glucose into two pyruvate molecules
– pyruvate and NADH enter fermentation
– energy from NADH converts pyruvate into lactic acid
– NADH is changed back into NAD+
•
Lactic Acid fermentation- in a shortage of
oxygen in your muscle cells, it regenerates
NAD+ so glycolysis can continue.
Lactic acid builds up in your muscles which
causes pain and soreness.
pyruvic acid + NADH  lactic acid + NAD+
• Lactic acid fermentation also occurs with
certain microorganisms to produce certain
foods; Ex. yogurt, sour cream and pickles
yogurt
Sauerkraut

4.6
Fermentation
TEKS 4B
Fermentation and its products are important in several
ways.
• Alcoholic fermentation is similar to lactic acid
fermentation. Occurs in YEAST CELLS
– glycolysis splits glucose and the products enter
fermentation
– energy from NADH is used to split pyruvate into an
alcohol and carbon dioxide
– NADH is changed back into NAD+
– NAD+ is recycled to glycolysis
Two Types of Fermentation:
Alcoholic fermentation- Performed by yeast
and other microorganisms
pyruvic acid + NADH  alcohol + CO2 + NAD+
• We can use this to help us make things
such as bread and wine
The Totals
• Cellular respiration produces 36 ATP molecules.
• More ATP is produced with oxygen than without.
Cellular respiration is more efficient using
oxygen.
2
2
32
The Totals
• Glycolysis: 2 ATP
• Fermentation: None! but regenerates
electron carriers for glycolysis
• Krebs Cycle: 2 ATPs
• Electron Transport Chain: 32 ATPs
Total Number of ATP produced:
• Anaerobic respiration: 2 ATP (From
glycolysis)
• Aerobic respiration: 36 ATP (From
glycolysis, kreb’s cycle and electron
transport chain)
Energy and Exercise: Quick
Energy
• Running a short race, you use ATP in your
muscles, and produce new ATP by lactic acid
fermentation and cellular respiration.
• When sprinting, you produce most of your ATP
using lactic acid fermentation because you have
run out of oxygen for the Krebs cycle.
• You breathe heavily after you finish a race to
rebuild your ATP supply.
Energy and Exercise: Long-term
Energy
• When running a long race, you use
carbohydrate energy stored as glycogen from
your muscles and other tissues. This will give
you enough energy for up to 20 minutes of
activity.
• After using up glycogen, your body will use up
fats for energy.
• Aerobic exercises like running and swimming
are beneficial for weight control.
REVIEW
Comparing Photosynthesis and
Cellular Respiration
• If storing energy is compared to money in
a savings account, photosynthesis
deposits the energy and cellular
respiration withdraws the money.
• Cellular Respiration is the reverse reaction
of photosynthesis.
• What is the formula for photosynthesis?
– 6CO2 + 6H2O + light  6O2 + C6H12O6
• What is the formula for cellular respiration
(think about the opposite)?
– 6O2 + C6H12O6  6CO2 + 6H2O + ATP
– Photosynthesis uses CO2 in the atmosphere,
but cellular respiration puts it back
– Photosynthesis releases O2 into the
atmosphere but cellular respiration using O2
to release energy from the food
– Cellular respiration occurs in all eukaryotes
and some prokaryotes
– Photosynthesis occurs only in plants, algae,
and some bacteria. Other organisms
(heterotrophs) get their food by consuming
other organisms.
Which path produces the most
ATP?
•
•
•
•
Where does glycolysis take place?
What phrase means without oxygen?
What phrase means with oxygen?
Where does the Krebs Cycle take place?
Which path produces the most
ATP?
• Where does the Electron Transport Chain
take place?
• What is the NET ATP for anaerobic
respiration?
• What is the NET ATP for aerobic
respiration?
• Which path produces the most ATP?