Cell Energy
• All living organisms must be able to obtain energy
from the environment in which they live.
• Plants and other green organisms are able to trap
the light energy in sunlight and store it in the bonds
of certain molecules for later use.
Cell Energy
• Other organisms cannot use sunlight directly.
• They eat green
plants. In that
way, they obtain
the energy stored
in plants.
Work and the need for energy
•
Some examples of cell processes that require
energy.
1. Active transport
2. cell division
3. Movement by use of flagella or cilia
4. production, transport, and storage of proteins
• There is a molecule in your cells that is a quick
source of energy for any organelle in the cell that
needs it.
Work and the need for energy
• The name of this energy molecule is adenosine
triphosphate or ATP for short.
• ATP is composed of an adenosine molecule with
three phosphate groups attached.
Forming and Breaking Down ATP
• The charged phosphate groups act like the positive
poles of two magnets.
• Bonding three phosphate groups to form adenosine
triphosphate requires considerable energy.
Forming and Breaking Down ATP
• When only one phosphate group bonds, a small
amount of energy is required and the chemical bond
does not store much energy. This molecule is
called adenosine monophosphate (AMP).
• When a second phosphate group is added, more
energy is required to force the two groups together.
This molecule is called adenosine diphosphate, or
ADP.
Forming and Breaking Down ATP
• An even greater amount of energy is required to
force a third charged phosphate group close enough
to the other two to form a bond.
• This molecule is called Adenosine triphosphate or
ATP.
• When this bond is broken, energy is released.
Forming and Breaking Down ATP
• The energy of ATP becomes available to a cell
when the molecule is broken down.
Adenosine
P
P
P
Adenosine triphosphate (ATP)
P
P
Adenosine diphosphate (ADP)
Adenosine
P
P
ATP (Adenosine triphosphate)
• Most important energy
storing compound in living
things.
• ATP is produced from a low
energy compound called
ADP.
• ADP is for Adenosine
diphosphate.
• The energy that is produced
in these molecules is from
the breaking of the bonds
when ATP becomes ADP.
Trapping Energy from Sunlight
• The process that uses the sun’s energy to make
simple sugars is called photosynthesis.
Photosynthesis
Photosynthesis is the process in which autotrophs convert
sunlight into food energy (sugars and starches).
OR
6CO2 + 6H2O + light ---> C6H12O6 + 6O2
OR
Carbon Dioxide + Water + Sunlight ---> Glucose + Oxygen
autotrophs --organisms which make their own food using
photosynthesis.
6CO2 + 6H2O + light energy ---> C6H12O6 + 6O2
Photosynthesis in the Chloroplast
• The process of
photosynthesis takes place in
the chloroplast, specifically
using chlorophyll, the green
pigment involved in
photosynthesis.
• the parts of a chloroplast include
the stroma, and thylakoids
stacked in grana. The chlorophyll
is built into the membranes of
the thylakoids.
Photosynthesis (light & dark reaction)
• There are two
reactions that make
up photosynthesis,
light reaction and
dark reaction.
• Light reaction
occurs in the
thylakoid of a grana
in a chloroplast.
Light that carry’s out Light
Reaction.
• The color of light that
triggers light reaction is
not green.
• The color of light that is
absorbed are violet, blue
and red.
• The wavelength of these
colors cause electrons to
move and produce high
energy molecules of ATP
& NADPH & the release
of oxygen
Light Reaction
Light Reaction (con’t)
• ATP is produce from a
low energy molecule
called ADP.
• NADPH is produce
from a low energy
molecule called
NADP+.
• Oxygen is produce
from the splitting of
the water molecule.
Trapping Energy from Sunlight
Click image to view movie.
ATP and Dark Reaction
• The ATP along with NADPH
that is produced in light
reaction is used to carry out
the 2nd reaction Dark
Reaction. This reaction is
also known as the Calvin
Cycle or carbon fixation.
• The Dark Reaction occurs in
the Stroma of the Chloroplast
of a plant cell. (note that CO2
is also needed in this
process).
stroma
Dark Reaction (con’t)
• Dark reaction is lightindependent which means
it does not require light.
• Just because its called
dark reaction doesn’t
mean it occurs only at
night.
• Dark Reaction (aka Calvin
Cycle) is the final stage of
producing GLUCOSE the
energy storing compound
that is needed for other
organisms.
Dark Reaction aftermath
• You may think this
concludes photosynthesis,
but the ATP & NADPH
use to carryout dark
reaction is now converted
back to ADP & NADP+ in
the light reaction which
can later be repowered as
high energy molecules.
• The Glucose (Sugar)
molecules is now
available for organisms to
eat.
The Calvin Cycle
Cell Respiration
• The process in which a cell breaks down sugar or other
organic compounds to release energy as ATP
OR
C6H12O6 + 6O2  6CO2 + 6H2O + ATP
OR
Glucose +
Oxygen  Carbon Dioxide + Water + Energy
• The primary objective of cell respiration is producing ATP
Cell Respiration in the
Mitochondrion
• Mitochondrion is known as the
“powerhouse”or “power-pack”
of a cell. Because, of its ability
to produce energy known as
ATP.
• Majority of Cell Respiration
occurs in the Mitochondria.
• The 2 places that cell respiration
occurs are the matrix ( fluid
filled compartments) & the inner
membrane called the cristae
Cell Respiration (Glycolysis)
• Cell Respiration has three
parts, Glycolysis, Krebs
Cycle, and Electron
Transport Chain.
• Cell respiration begins
with Glycolysis "sugar
splitting.” conversion of
glucose to pyruvic acid or
(pyruvate: a 3 carbon
molecule)
• Glycolysis occurs in the
cytoplasm (cytosol) of a
cell.
Electron Carriers used to make ATP
Glycolysis (con’t)
• During glycolysis glucose is
split into 2 pyruvate and 2
NADH, and a net gain of 2
ATP molecules are produced.
• The 2 NADH (electron
carrier) will later enter into
the Electron Transport Chain
to form ATP.
• The 2 pyruvate molecules
will now enter into the Krebs
Cycle
Krebs Cycle (Citric Acid Cycle)
• This reaction occurs in the matrix
of the mitochondria
• The 2 pyruvate produce in
glycolysis goes through a series
of reactions releasing 2 ATP, 8
NADH, 2 FADH2 & CO2.
• The molecules of NADH, FADH2
(electron carriers) is now
transported to the electron
transport chain to produce more
ATP.
• The cycle must go around 2
times, once for each pyruvate.
Flavin Adenine Dinucleotide (FAD)
It picks up two Hydride ions along
with their bonding electron
pairs to produce FADH2
Electron Transport Chain
• This reaction occurs in the
inner mitochondrial
membrane called cristae.
• Molecules of NADH and
FADH2 are considered to be
electron carriers that are used
to form ATP from ADP.
• For every NADH, 3 ATP
molecules are formed. (With
one exception)
• For every FADH2, 2 ATP
molecules are formed.
Electron Transport Chain (con’t)
• This reaction delivers
about 90% of all ATP
formed during cell
respiration.
• Water is also formed with
the addition of Oxygen
during the Electron
Transport Chain.
• NADH & FADH2 are now
reduced to NAD+ and
FAD.
Aerobic Respiration
• There are two types of cell
respiration.
• One that requires Oxygen
is called aerobic
respiration. Some
microorganisms that use
oxygen in respiration are
called aerobes.
• This is the type of
respiration that we have
been discussing in the
notes.
Anaerobic Respiration
• Anaerobic respiration does not
require oxygen. Anaerobes are
microorganisms that are poisoned
by oxygen.
• There are two types of anaerobic
respiration, lactic acid fermentation
and alcohol fermentation.
• Lactic acid fermentation occurs in
microoganisms and muscle cells.
• We use bacteria to produce yogurt.
The sour taste comes from the lactic
acid released from anaerobic
respiration
Lactic Acid Fermentation (con’t)
• Another form of lactic
acid fermentation occurs
when your body has
exhausted its oxygen for
aerobic respiration, it then
converts to LAF
• You may recognize this
reaction when you feel
soreness. This soreness is
the buildup of lactic acid
in the muscle tissue
Alcohol Fermentation
• Another type of anaerobic
respiration is alcohol
fermentation. This form of
respiration occurs in yeast.
• We use this form of respiration
causing bread to rise(CO2
causes the bread to rise, the
alcohol evaporates) and in the
production of ethanol (ethyl
alcohol) and alcohol products.
Which of the following chemical equations
represents cellular respiration?
A.6CO2 + 6H2O  C6H12O6 + 6O2
B.14H+ + Cr2O< > -2 + 6I -  2Cr+3 + 3I2 + 7H2O
C.C6H12O6 + 6O2  6CO2 + 6H2O
D.C< > H16 + 11O2  7CO2 + 8H2O
Biology EOI Question 17 Answer
C - Cellular respiration breaks down glucose,
C6H12O6, and releases carbon
dioxide, CO2, and water, H2O.
Only choices A and C have glucose in them. Choice
A is the chemical equation for
photosynthesis, the reverse of respiration.
Choice B is a redox equation that has chromium in
it that might be harmful to
cells. Choice D is the chemical equation for
combustion (the burning of a
hydrocarbon).
The diagram above shows some of the stages in cellular
respiration. Which of the following
gives the stages in the correct order?
A.Electron transport system, Krebs cycle, glycolysis
B.Glycolysis, electron transport system, Krebs cycle
C.Krebs cycle, glycolysis, electron transport system
D.Glycolysis, Krebs cycle, electron transport system
Biology EOI Question 46 Answer
D - No other choice has the three
stages in order.
33. This apparatus was used to collect the oxygen that was
produced by Elodea. Which factor was most responsible for the
production of oxygen by Elodea?
A.Sugar was present in the liquid.
B.The liquid contained enough oxygen for the plant to absorb.
C.The presence of light stimulated photosynthesis.
D.The plant contained a large number of mitochondria.
Biology EOI Question 33 Answer
C - Energy for photosynthesis
comes from light.
Web Links
• http://www.cst.cmich.edu/users/baile1re/bio
101fall/enzphot
A.
D
B
C