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Energy in a Cell
ATP: Energy in a Molecule
 Photosynthesis: Trapping Energy
 Cellular Respiration: Getting
Energy to Make ATP
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ATP: Energy in a Molecule
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Cell energy
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Organisms and their cells need an endless supply
of energy in order to function
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Energy to walk, talk, bend, exercise
Cells get energy from the food you eat
Organisms break down food into small nutrient
molecules that can enter your bloodstream
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Cells then break down the food molecules
Cells use some of the ATP from the food molecules,
then store the rest
ATP: Energy in a Molecule
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ATP
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ATP is known as the cell’s “money”
Cells must have plenty of ATP “money” to spend
whenever the cell needs to work
Without a constant supply of ATP, the cell will die
Cells use to ATP for many things
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make ribosomes
help with cell division
for active transport
Maintain homeostasis
The ATP molecule
ATP: Energy in a Molecule
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Forming and breaking down ATP
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Cells store energy by adding a phosphate group to
a ADP
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When cells use energy, the process works in
reverse
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ADP + P  ATP (energy)
Adenosine diphosphate  adenosine triphosphate
ATP  ADP + P (energy is released)
The process is then ready to start all over again
Redox Reactions
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Most of the important energy changes in
organisms involve chemical reactions known
as oxidation reduction reactions.
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Photosynthesis & cellular respiration are
oxidation reduction reactions.
Oxidation
Involves the :
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Releases Energy
Combining with Oxygen
Loss of Electrons
Loss of Hydrogen
Reduction
Involves the:
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Absorption of Energy
Separation from Oxygen
Gain of Electrons
Gain of Hydrogen
LEO the Lion goes GER
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Loss of Electrons is Oxidation
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Gain of Electrons is Reduction
Photosynthesis: Trapping Energy
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Autotrophs/the producers of the planet
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Autotrophs are organisms that can make their own
food (plants)
Autotrophs make their own food through the
process of photosynthesis
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They make simple sugars that other organisms can
break down into ATP
Autotrophs trap energy from sunlight and use the energy
to build carbohydrates (sugars)
Photosynthesis: Trapping Energy
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The green pigment chlorophyll absorbs
sunlight
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Found in the chloroplasts
Plants also have other colored pigments that help
trap sunlight
These pigments give plants their bright colors
Chlorophyll
Photosynthesis
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The process by which plants use light energy
to make food molecules from CO2 & H2O
Larry the Sun
H+
Light
O2chlorophyll
zapped within
chloroplast
H2O
ATP
Light Reaction
Calvin the Moon
CO2
H+
glucose or
C6H12O6 or
sugar
ATP
(from light reaction)
(Dark Reaction)
Calvin Cycle
Photosynthesis: Trapping Energy
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Photosynthesis: the basic steps
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1st step – chloroplasts trap sunlight
2nd step – light energy is converted to chemical
energy (sugar) and then stored
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Water and carbon dioxide are also required for this step
The general equation for photosynthesis is:
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6CO2 + 6H2O + light energy  C6H12O6 + 6O2
carbon dioxide plus water plus light produces sugar and
oxygen (in the presence of chlorophyll)
Photosynthesis: Trapping Energy
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Photosynthesis
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There are 2 main groups of reactions that take
place during photosynthesis
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Light reactions
Calvin cycle (formerly called the dark reaction)
Light reactions occur when light energy is
converted to chemical energy
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This is the photo part of photosynthesis
These reactions split water molecules and provide the
energy for the Calvin cycle
Photosynthesis: Trapping Energy
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Photosynthesis
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The Calvin cycle
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The series of reactions that form simple sugars using
carbon dioxide and hydrogen (from water)
The Calvin cycle is the synthesis part of photosynthesis
Photosynthesis: Trapping Energy
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The Light Reactions
1)
2)
3)
4)
5)
Light strikes chlorophyll
Electrons gain energy and jump out of
chlorophyll
The electrons move down the electron transport
chain
The electrons give off energy, which is used to
make ATP
Electrons from water move to the chlorophyll, to
replace the lost electrons
Photosynthesis: Trapping Energy
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The Light Reactions
6)
7)
8)
9)
Water breaks up into hydrogen and oxygen
Light causes the electrons to gain energy and
leave the chlorophyll again
Electrons and hydrogen are added to NADP+,
which produces NADPH + H+
The ATP made in the light reactions will be used
in the 2nd stage of photosynthesis – the Calvin
cycle
Electron transport chain
Photosynthesis: Trapping Energy
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The Calvin Cycle
1.
This is a complex chemical reaction that uses
ATP to make simple sugars
1.
2.
3.
4.
A 5 carbon sugar is formed
It breaks into two 3 carbon sugars
The two 3 carbon sugars go through some chemical
reactions and finally make a 5 carbon sugar
The process starts again when a carbon from CO2 is
used to turn the 5 carbon sugar into a 6 carbon sugar
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This is called carbon fixation
The Calvin Cycle
Photosynthesis: Trapping
Energy/Locations
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Overview :Light reaction and Calvin cycle
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Light reactions take place in the thylakoids
The Calvin cycle takes place in the stroma
The light reactions make the ATP that is used to
make sugar (food) during the Calvin cycle
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Animals then eat the sugars to get energy they need to
survive & thrive
Now….Add the Photosystems
a)
(PSII) Light is absorbed by ?? or other pigments in
photosystem II. This E from ?? is then transferred to
electrons which are then passed down the ??. Separately
enzymes break apart ?? Into electrons & of ?? Ions & ??.
a)
(ETC) Electrons from ?? move though the ETC to
photosystem I. E from this process are used to transport ??
ions from the stroma into the inner ??.
a)
(PSI) As in PSI, pigments add E from light to the electrons.
The high E electrons are then picked up by NADP+ to form
??.
And then…
d) (H ion movement) The inside of the ?? fills with H + ions,
giving the membrane an overall charge. The difference in
charges provides the E to make ATP.
e) (ATP formation) A protein called ??? allows the H ions to pass
through & it rotates (like a turbine with water running over it
at a hydroelectric power plant). As this happens the protein
binds ADP & PO4 to produce ???.
Photosynthesis: Trapping Energy
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Life without light
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Some organisms are able to energy without
sunlight
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Mainly bacteria
They are chemosynthetic – they are autotrophs that can
use different chemicals to produce methane
These types of bacteria live near deep cracks in the
ocean floor
Chemosynthetic vent worms