7.1 Sunlight powers life
I. Obtaining Food
A. Autotrophs are organisms that obtain their
energy through the process of
photosynthesis such as green plants (aka
self feeders, producers)
B. Heterotrophs are organisms that cannot
make their own food but must obtain it from
another source. Animals are heterotrophs
and depend on producers for energy (aka
consumers)
II. Harvesting the Energy in
Food
A. Plants and certain other producers use
light energy to make organic
molecules (energy source).
1. H2O and CO2 are the raw ingredients
2. Glucose (C6H12O6) and O2 are the
products
3. Occurs by rearranging the atoms
Harvesting the energy
B. Cellular Respiration is the process that
converts this stored organic chemical
energy into a usable form ATP
(adenosine triphosphate)
C. Both plant and animal cells then use
ATP for energy and release CO2 and
H2O (fig. 7.3)
Photosynthesis and Cellular
Respiration
7.2 Food stores chemical
energy
I. What is Energy? Forms of?
A. The ability to perform work or to move
against an opposing force.
B. Kinetic Energy: Energy of motion
C. Potential Energy: Stored energy
D. B and C are inversely proportional!
II. Law of Conservation of
Energy
A. You cannot create or destroy energy you
can only change its form.
B. Random molecular motion: Thermal
energy!
1. Caused by atoms bouncing of off each other.
2. Thermal energy transferred from warmer to
cooler is called Heat. (Can’t be retrieved and put
back to work that is one reason why we must
continue to eat.)
Law of conservation of energy
C. Stored potential energy: Chemical
energy!
1. Potential to perform work is due to
arrangement of the atoms and the bonds
holding them together. (create bond =
stored energy; break a bond = release of
energy)
2. Almost all organisms use one or more of
the following: Carbohydrates, Fats, and
Proteins (fig. 7-5)
Stored chemical energy of food
III. Chemical Energy at Work.
A. Cells vs. Engines: both work by
breaking down complex chemicals into
simple ones (breaking bonds!)
B. Both use O2 to accomplish this and
some energy is converted to thermal
(heat). (fig. 7-7)
C. Cell slower and more efficient than
auto engines.
Oxygen helps convert energy
IV. Calories: Units of Energy
A. Amt. of energy required to raise 1g of H2O
by 1 deg. C. (very small)
B. We use kcal or 1,000 calories. (food labels)
C. Calorimeter used to determine kcal. by
burning dried food. (H2O has no kcal’s)
D. Cells use enzymes not flame to release
energy thus it is easier to manage
Calories of
activities
7.3 ATP provides energy for
cellular work
I. How ATP Packs Energy
A. Draw fig. 7-9.
B. A=Adenine and 5-C sugar
T=Tri or Three (ref. to # of P)
P=Phosphate
C. Each P is a neg. charged molecule since
likes repel, they want to separate from each
other- this contributes to the amount of
potential energy avail. in each bond. (break
bond=release energy)
ATP structure
II. ATP and Cellular Work
A. Chemical reactions break ATP’s P bonds.
B. Enzymes enable this to occur.
C. The molecule that undergoes the change
drives the work (creatine phosphate)
D. Cells perform 3 types of work (fig. 7-10
1. Mechanical: muscle contraction
2. Chemical: building/breaking large
molecules
3. Transport: pumping molecules across cell
membrane
Types of Cell Work
III. The ATP Cycle
A. ATP continuously converts to ADP
and back
B. ADP can be converted back to ATP by
reattaching the P with energy from
foods organic molecules
C. A working muscle regenerates all of its
ATP molecules about once each min.
or 10 million per sec.
ATP <--> ADP + P
7.4 Electrons fall from food to
oxygen during cellular
respiration
I. Relationship of Cellular
Respiration to Breathing
A. Aerobic process-requires O2
B. O2 into the cell and out
C. Cellular respiration is not breathing
or exchange of gasses in the lungs (fig.
7-12)
Breathing and ATP
II. Overall Equation for
Cellular Respiration
A. Glucose+Oxygen-->Carbon Dioxide +
Water + ATP
B. C6H12O6 + 6O2 --> 6CO2 + 6H2O + 38 ATP
C. Main function is to create 38 ATP for
each glucose
Cell Respiration Equation
III. “Falling” Electrons as an
Energy Source
A. Falling elect. like waterfall-at the top the
potential energy is high as it falls it becomes
less
B. Atom’s positive nucleus pulls negative
electrons the closer they get the more
potential energy they lose.
C. Positive O2 pulls strongly on electrons in the
H2 and C thus rearranging the atoms and
releasing energy.
IV. Electron Transport Chain
A. Controlled fall of electrons “step-bystep” walk.
B. Not burst (like flame) but series of
controlled reactions
C. Electrons passed by carriers until O2
finally pulls electrons off at the end to
form H2O and release energy to make
ATP.
ETC like staircase
7.5 Cellular respiration
converts energy from food to
energy in ATP
I. Mitochondria Structure
A. Outer membrane and Inner highly folded
membrane enclosing thick fluid called matrix
B. Folds increase amt. of surface area for more
reactions to occur. (fig. 7-16)
C. All chemical processes make up a cell’s
metabolism
D. Specific enzymes catalyze (speeds up)
each reaction in a metabolic pathway
Mitochondria
Overview of Cell Respiration
II. Stage I: Glycolysis
(splitting of sugar)
A. Occurs in cytoplasm (fig.7-17)
B. 2 ATP “initial investment” to break the
sugar
C. 1 C6H12O6 in and 2 pyruvic acids out
(3-C each)
D. 2 ATP spent and 4 produced (net gain
of 2)
Glycolysis
Glycolysis
Glycolysis
Glycolysis
Glycolysis
Glycolysis
1. What are the products of glycolysis?
4 ATP molecules (net gain of 2) and 2
molecules of pyruvic acid
Glycolysis
2. Explain the terms energy-investment phase
and energy-harvest phase.
Energy-investment phase refers to the part of the
reaction in which two molecules of ATP are used,
while energy-harvest phase describes the part of
the reaction that generates four molecules of ATP.
III. Stage 2: The Krebs Cycle
A. Occurs in the matrix
B. Occurs twice for each glucose that
entered stage one
C. Produces 1 ATP and electron carrier
molecules
Krebs Cycle
Krebs Cycle
Krebs Cycle
1. What is the overall result of the
Krebs cycle?
Pyruvic acid is broken down, forming carbon dioxide and
releasing energy.
Krebs Cycle
2. How is acetyl CoA related to
the process?
One pyruvic acid molecule is converted to one molecule of
acetyl CoA, which enters the Krebs cycle.
IV. Stage 3: Electron Transport
Chain and ATP Synthase Action
A. Occurs in the inner membrane of mitoch.
B. Refer to the previous information on “falling
electrons” 7-4.
C. Hydrogen ions pumped across the
membrane to store energy like a dam holding
back water
D. ATP synthases (enzymes) act like mini
turbines to convert ADP back into ATP slowly.
E. As many as 38 ATP’s produced for each
glucose that entered glycolysis.
ETC and ATP Synthase
ETC and ATP Synthase
ETC and ATP Synthase
ETC and ATP Synthase
ETC and ATP Synthase
ETC and ATP Synthase
ETC and ATP Synthase
1. What is the end result of the process
shown here?
ATP is generated.
ETC and ATP Synthase
2. How is the movement of H+ ions related to this process?
Energy released by the chain pumps H+ ions across a
membrane. The H+ ions flow back through ATP synthases,
generating ATP.
Overall ATP production
7.6 Energy without oxygen
I. Fermentation in Human
Muscle Cells
A. Fermentation makes ATP without using
oxygen
B. This process is entirely glycolysis, which
does not produce a lot of ATP compared to all
of cellular respiration but it is enough for short
bursts of energy
C. The byproduct of fermentation is the build up
of lactic acid in your muscles, this is the
soreness you feel after intense exercise
II. Fermentation and microorganisms
A. Like your muscles, yeast is capable of both
cellular respiration and fermentation
B. When yeast is kept in an anaerobic
environment, they are forced to convert sugar
and other foods.
C. Instead of producing lactic acid as a waste
product, fermentation in yeast cells produces
alcohol and carbon dioxide
D. There are also fungi and bacteria that produce
lactic acid during fermentation and help transform
milk into cheese and yogurt giving them their
characteristic flavors
Fermentation
Fermentation
Fermentation
Fermentation
Fermentation
1. How are the two types of fermentation similar? How are they different?
Each process starts with glucose, produces two molecules of ATP, and has an intermediate
product of pyruvic acid. Fermentation in muscle cells produces lactic acid, while
fermentation in yeast produces carbon dioxide and ethyl alcohol.
Fermentation
2. Why is there no net gain of NADH in either process?
In each process, 2 molecules of NADH are generated in the first step, but
2 molecules of NADH are used in the second step.