Biology
Mr. Solis
Energy is essential to life.
Metabolism involves using energy to build or
breakdown molecules.
 Some organisms trap sunlight for energy.
(Autotrophs)
 Others eat to obtain energy. (Heterotrophs)
 The need for energy is important for cell movement,
active transport, cell division and reproduction.
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ATP- adenosine
triphosphate. 1adenosine molecule
and 3 phosphate
groups.
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Phosphate Groups have polarity
which requires a lot of energy to
add these groups to adenosine.
When the ATP molecule only
has one phosphate group, it is
called AMP Adenosine
monophosphate.
Energy is required to add a
second Phosphate group and
the name becomes Adenosine
diphosphate.
When the third group is added
then the name changes to
adenosine triphosphate.
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The energy that becomes
available for the cell is when the
molecule is broken down back to
ADP. Since it took a lot of
energy to add the phosphate
group. Then a lot of energy is
released.
Protein with in the cell attach
themselves to ATP and as soon
as the Phosphate group is
uncoupled, the protein releases
the ADP and a new ATP attaches
itself to protein.
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Makes new molecules
Maintain homeostasis
Keeping needed substance in the blood
stream.
Cellular movement
Trapping Energy from
sunlight to create
sugars which will later
be used for energy.
 Photosynthesis
happens in two phases.
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▪ Light-dependent reactions
▪ Light-independent
reactions
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Convert Light energy to
chemical energy.
This occurs when sunlight
strikes the chlorophyll.
Light is transferred to
electrons, which then
passes through an electron
transport chain.
An electron transport chain
is a series of proteins
embedded in the thylakoid
membrane.
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These energized electrons provide energy to
bond Phosphate groups to ADP and form
ATP.
Or it splits water to release oxygen to form
NADPH.
These two are used for light-independent
reactions.
The Third Stage is
called Calvin Cycle.
 This is composed of
series of enzyme
reactions that use
carbon dioxide to form
sugars. (Carbon
dioxide fixation)
 This takes place in the
stroma.
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1.
2.
3.
4.
Each molecule of CO2 is added to a five carbon
compound by an enzyme.
The result is a 6 carbon compound. This compound
splits into 2 three carbon compounds.
One of the three is used to make organic
compounds. Used for stored energy.
The other three carbon sugar is used to regenerate
the initial five carbon compound.
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Light intensity: as it increases
photosynthesis increases. As all pigments are
used, it reaches saturation point and
photosynthesis level off.
Temperature: Unfavorable temperatures
may inactivate certain enzymes.
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The process by which
mitochondria breaks down food
molecules to form ATP is called
respiration.
Stages in Cellular Respiration
 Glycolysis
 Citric Acid Cycle also called
Krebs Cycle
 The electron transport chain
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Series of chemical
reactions in the cytoplasm
of a cell that breaks down
glucose into two pyruvic
acid and a three carbon
compound. This is also
called anaerobic
respiration. No oxygen is
required for this reaction to
occur.
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Also known as the krebs cycle, is a series of
chemical reactions similar to the Calvin cycle
in that the molecule used in the first reaction
is also one of the end products.
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Anaerobic process that follows glycolysis and
provides a means to continue ATP until
oxygen is available again.
Lactic Acid Fermentation: is one of the
process that supplies energy when oxygen is
scarce.
Alcoholic Fermentation: is used by yeast cells
and some bacteria to produce CO2 and ethyl
alcohol.
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Photo
Food synthesized
Energy from sun stored in
glucose
CO2 taken in
O2 given off
Produces sugars
Requires sunlight
Occurs only in the
presence of chlorophyll
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Cellular
Food broken down
Energy of glucose released
CO2 given off
O2 taken in
Produces H2O and CO2
Does not require light
Occurs in all living cells.