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CELL ENERGY
All cells need energy.
Energy is the capacity to
move or change matter.
Forms of energy important
to life:
chemical
radiant
mechanical
electrical
Energy can be transformed
from one form to another.
Energy of motion is called
Kinetic
Energy that is stored is
Potential
Laws of energy:
1. Energy may be
converted from one
form to another
but not destroyed.
2. Some usable energy
is always lost
during conversion.
Cells store energy in the
bonds of molecules.
Breaking molecular bonds
is a way to get energy
for cell processes like:
active transport
cell reproduction
producing cell products
movement
A major energy storage
molecule is glucose.
Glucose may be stored
as starch in plants or
glycogen in animals.
Energy may also be stored
in the bonds of lipids and
even proteins.
Long term energy storage
is important, but cells
need lots of energy fast.
The main cell compound for
short term energy storage
and release is ATP,
Adenosine tri-phosphate
composed of:
a) adenine, a base
b) ribose, a sugar
c) phosphate, an ion
Energy is stored in the
phosphate bonds.
Cells can use energy from
the breakdown of ATP
and store it in the third
phosphate bond to make
ATP from ADP.
ATP can be sent all over
the cell quickly to give
energy where needed but
it must be constantly
regenerated.
All organisms need energy.
Heterotrophs get energy by
“eating”.
For example:
animals,
fungi,
some bacteria,
some protists
are heterotrophs.
Autotrophs get energy from
the sun.
For example:
plants,
algae,
some bacteria
some protists
Only about 10% of the
species on Earth are
Autotrophic.
Some are chemosynthetic.
Converting unusable sunlight
into usable chemical energy
is called:
Photosynthesis
6H2O + 6CO2 ―›
C6H12O6 + 6O2
Chlorophyll is the chemical
that can capture the energy
of sunlight.
Chlorophyll is found in
organelles called
Chloroplasts
Photosynthetic cells may
contain hundreds of
chloroplasts.
Other pigments like
Carotenoids (orange)
Anthocyanins (redish)
Xanthophylls (yellow)
can absorb light that
chlorophyll can’t.
There are two sets of
reactions in photosynthesis
1. Light dependent
2. Calvin Cycle
Light dependent reactions:
Chlorophyll absorbs
energy and uses it to:
convert ADP to ATP
ADP + P
ATP
break apart water to
get H+ and produce O2
convert NADP+ to NADPH
+
+
NADP + 2e + H
NADPH
Light dependent reactions
take place on the thylakoid
membranes.
Calvin cycle:
Reactions take place in the
stroma and do not need
light energy.
Uses energy from ATP,
+
H and e from NADPH
CO2 from the air to
make glucose C6H12O6
Summary of photosynthesis
Factors that affect the
rate of photosynthesis:
light intensity
temperature
length of daylight
CO2 levels
air pollution