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Cellular Respiration &
Photosynthesis
Background Information
Producers: are able
to convert the sun’s
energy into glucose
through a process
called photosynthesis
 Include plants, some
protists and bacteria
 AKA autotrophs


Photosynthesis
requires a special set
of pigments called
chlorophylls to trap
the sunlight in order
to make glucose from
the water and CO2
from the atmosphere
Background Information (con’t.)
Consumers: eat
 Consumers are AKA
producers or other
heterotrophs
consumers in order to  Fungus, bacteria and
get the stored glucose
some protists are part
to use for their own
of a specialized group
needs
of consumers AKA
 Includes animals,
decomposers (AKA
some protists &
saprophytes) that eat
bacteria
dead organic material

Food Chain Vocabulary
Food Webs
Food webs are simply
overlapping food
chains
 Food webs are
complex diagrams
showing the
relationships between
many different
organisms

Energy
Potential energy is
stored energy that
could be used for
work
 The chemical energy
stored between the
bonds of atoms is a
type of PE.
 All bonds (ATP, sugar,
protein, lipid) store
energy

Kinetic energy is
energy of motion,
work being done
 Kinetic energy that
does not get work
done is called thermal
energy (heat)
 When bonds are
broken, some of the
energy is released as
heat

Adenosine Triphosphate
(ATP)
ATP

ATP is broken down
to release the energy
between the high
energy bonds of the
phosphate groups

ATP  ADP + Pi

ATP is required for
cells to do their work
and is made from
food

ATP can be made
from spare phosphate
groups and ADP

ADP + Pi  ATP

This process is called
cellular respiration
and occurs in the
mitochondrion of
eukaryotic cells
ATP Review
ATP is the energy
 The reason for this is
‘currency’ of your cells
that ATP is a very
small molecule
 All foods entering the
body convert the
 This allows a large
chemical energy
amount of energy to
stored between their
be used quickly and
bonds into the high
easily in the cell
energy bonds
 ATP’s small size also
between the
allows it to travel
phosphate groups of
quickly throughout
ATP
the cell

Cellular Respiration
Results in ATP
production
 Occurs in the
mitochondrion
 The mitochondrion
has an inner
membrane AKA the
cristae (the folds)
 The center of the
mitochondrion is
called the matrix

Cellular Respiration

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
Aerobic Respiration
Requires oxygen
which acts as the
‘final electron
acceptor’ in the ets
Requires a
mitochondrion
Results in 38 ATP per
glucose molecule
Eukaryotes

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Anaerobic Respiration
Does not require
oxygen
Does not require a
mitochondrion
Results in 2 ATP per
glucose molecule
Prokaryotes (and
eukaryotes in certain
situations)
1st Phase: Glycolysis

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
The 1st stage of
respiration
Occurs in the
cytoplasm
Converts a 6 Carbon
glucose into two 3
Carbon pyruvates
Net gain of 2 ATP
Electron carriers also
generated for later
use (2 NADH)
Transition step to
Kreb’s cycle: the two
3 Carbon pyruvates
are converted into
two 2 Carbon acetylcoA molecules
 Electrons are
generated and
transferred to 2 more
NADH carriers
 Carbon dioxide is
released

Glycolysis
Glycolysis

Animation: http://highered.mcgrawhill.com/sites/0072507470/student_view0/
chapter25/animation__how_glycolysis_wo
rks.html
2nd Phase: Kreb’s Cycle
Occurs in the matrix
of the mitochondrion
 The 2 C acetyl-CoA
enters the cycle and
joins with a 4 C
compound
 Many different
compounds are
formed and broken
down in the Kreb’s
cycle (AKA citric acid
cycle)

Each time, electrons
are generated and
transferred to
electron carriers (6
NADH and 2 FADH2)
 These electrons are
needed for the ets
where most of the
ATP of respiration will
be made
 2 ATP are made

Kreb’s Cycle
Kreb’s Cycle

Animation: http://highered.mcgrawhill.com/sites/0072507470/student_view0/
chapter25/animation__how_the_krebs_cyc
le_works__quiz_1_.html
Final Phase: Electron
Transport Chain (ets or etc)
Where the bulk of ATP is made in aerobic
respiration
 Electrons are passed from one protein to
the next in the inner membrane (AKA
cristae) electron transport chain
 As they do, energy is released and used to
pump H+ ions into intermembrane space

Electron Transport Chain
H+ ions are allowed to flow back into the
matrix through the protein channel of the
ATP synthase enzyme
 The energy of the falling H+ ions is used
by the enzyme to make ATP
 Oxygen is AKA the final electron acceptor
of the electron transport chain. Without
it, the process stops and no more ATP can
be made

Electron Transport Chain

32-34 ATP can be generated per glucose
molecule through this method

The electron carriers that have left their
electrons at the electron transport chain
can now return to any of the previous
steps to get more electrons to bring back
to the etc
Electron Transport Chain
Hydroelectric Power Analogy
Cellular Respiration Summary
Glycolysis yields ATP and NADH, H20
released
 Transition step yields NADH, CO2
released
 Krebs cycle yields ATP, NADH & FADH2,
CO2 released
 ETS creates ATP, H20 is formed
 ETS requires the presence of O2 as the
final electron acceptor

Anaerobic Respiration
AKA Fermentation
Is simply glycolysis
 Occurs in cytoplasm (no
mitochondrion required)
 Prokaryotic organisms
use this process
 Eukaryotes may use
this process when
needed (not enough
oxygen)

Creates byproducts:
alcohol in yeast or
lactic acid in muscle
cells
 These byproducts
act as the final
electron acceptor of
electrons from the
NADH molecules (in
aerobic respiration,
the FEA is oxygen)

Cellular Respiration & Photosynthesis
Photosynthesis
General Equation for
photosynthesis:
CO2 + H20-chlorophyll
Glucose + O2

Notice that the
products of
photosynthesis are
the reactants of
aerobic respiration
Chloroplast
Thylakoids are the
individual
chlorophyll
containing
structures
 A granum is a
stack of thylakoids
 The stroma is the
fluid surrounding
the thylakoids

Leaf Cross Section
Photosynthesis
Photosynthesis
Light Reactions
 Take place across the
membrane of the
thylakoid
 Two photosystems
(PS I & II) capture
sunlight to create ATP
in ets and put
electrons in electron
carriers called NADPH
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Dark Reactions
AKA the Calvin cycle
This process of
‘carbon fixing’ takes
place in the stroma of
the choloroplast
1 turn of the Calvin
cycle produces 1 G3P
2 G3P = 1 glucose
molecule
Light Reactions
Chlorophyll in PS I and  Both the ATP and
NADPH enter the
II traps sunlight
stroma to complete
 The sunlight excites
the Calvin cycle
electrons which are
 Water splits to release
transferred to NADPH
electrons to replenish
electron carriers and
the supply at PS II
taken to the ets
 The ETS generates ATP  The electrons used in
the ets go to PS I to
necessary in the Calvin
replenish the electron
cycle to make G3P (2
supply there
G3P = glucose)

Dark Reactions
At the end of the dark
reactions, a molecule
known as G3P is
made
 2 G3P joined together
forms a glucose
molecule

We say that in this
phase carbon is ‘fixed’
 This means it is taken
from a gas state
(carbon dioxide) and
converted into a solid
state (glucose) which
can be used by our
bodies

Photosynthesis Summary
In the light reactions,
electrons from PS II
are used in an etc to
make ATP needed for
the dark reactions.
 Electron carriers
called NADPH are
filled at PS I to be
used in the dark
reactions

In the dark reactions
(Calvin cycle), ATP
and NADPH are used
to take CO2 and make
G3P
 2 G3P = 1 glucose
 Water and CO2 are
used and O2 is
released during the
process of
photosynthesis

The Carbon Cycle
Carbon is cycled
throughout the
environment in part
through the processes
of photosynthesis and
cellular respiration
 Carbon is stored in
organic material,
rocks (limestone),
and in the
atmosphere

The Carbon Cycle