Photosynthesis
& Cellular
Respiration
Ch. 8 & 9
All Living Things Require
Energy to Survive
• Photosynthesis- is the process
that converts the radiant energy
of sunlight into chemical energy
(glucose)
• Respiration-the process that
releases chemical energy for use
by the cell (in the form of ATP)
• Autotrophs
–Are plants
and other
organisms
that make
their own
food
–Ex. Green
plants
• Heterotrophs
–Cannot
make their
own food.
–Ex. animals
Photosynthesis- how
autotrophs produce chemical
energy
• 6CO2 + 6H2O
chlorophyll
Light energy
• Carbon dioxide + Water
C6H12O6 + 6O2
glucose + oxygen
Respiration- breaks down
glucose & release energy
• C6H12O6 + 6O2
6CO2 + 6H2O + ATP energy
• Respiration uses what photosynthesis
makes and vice versa
• Both photosynthesis & cellular
respiration happen in a series of steps
called biochemical pathways.
The energy released in
respiration is in the form of
adenosine triphosphate (ATP)
• An ATP
molecule has 3
parts.
– Adenine +
Ribose =
adenosine
– 3 phosphate
groups
• A-P (AMP) =
adenosine + 1
phosphate
• A-P~P (ADP) =
adenosine + 2
phosphate
• A-P~P~P (ATP) =
adenosine + 3
phosphates
~ = high energy bonds
When a cell needs energy,
an enzyme ATPase breaks
nd
the bond between the 2
& 3rd phosphate groups
A-P~P~P
ATP
ATPase
A-P~P +P + energy
ADP
To Add P to ADP is called
Phosphorylation
• The enzyme ATP synthetase has to
be present for this
A-P~P + P
ADP + P
A-P~P~P
ATP
ATP synthetase
Photosynthesis occurs in….
• Light Reaction
(occurs in light)
– Energy in sunlight is
trapped
– O2 is released
– ATP is formed
– NADPH2 is formed
– Occurs in the
thylakoids of the
chloroplast
• Dark Reaction/Calvin
Cycle (occurs in light or
dark)
– CO2 is fixed into organic
compounds
– ATP and NADPH2 act with
CO2
C6H12O6
(glucose)
– Happens in the stroma
of the chloroplast
Chloroplast-where
photosynthesis takes
place
• Inner membrane = discs called
thylakoids
• Thylakoids are surrounded by fluid
called stroma
•
•
•
•
Sunlight travels in waves.
Short waves have more energy than long
Pigments absorb lightwaves
5 different kinds of chlorophyll (a pigment)
– Chlorophyll a & b are most common
(absorbs many lightwaves and reflects
green.
– Carotenoids also absorb lightwaves
(yellow, orange, brown)
•Carotenes
•Xanthophylls
– Phycobilins (red and blue)
Respiration
• Releases the energy stored in the
chemical bonds of glucose.
• 2 kinds of respiration
• Both begin with glycolysis-occurs in
cytoplasm
– Breakdown of glucose into 2 pyruvic
acid molecules.
– Results in the production of 4 ATP
molecules
2 Kinds of Respiration
• Fermentationpyruvic acid is
broken down
without the use of
oxygen
• Glycolysis +
fermentation =
anaerobic
respiration
• Aerobic
respiration-pyruvic
acid is broken
down with the use
of oxygen.
2 Kinds of Fermentation
• Lactic Acid– Occurs in animal
cells and causes
muscle fatigue
• Alcoholic– Occurs in plant cells
and in yeast
– Produces ethyl
alcohol
Aerobic Respiration
• Releases a lot more energy than
anaerobic respiration (38 ATP’s)
• C6H12O6 + 6O2
6CO2 + 6H2O +
38ATP’s
• Occurs in the cell’s mitochondria
Aerobic Resp. happens in a
series of steps
1st-glycolysis-glucose is broken down
into pyruvic acid
2nd conversion of pyruvic acid to
acetyl-CoA
3rd (Krebs Cycle or Citric Acid Cycle)completes the breakdown of glucose
4th Electron transport chain- more ATP
is produced
• Aerobic Respiration = 38 ATP’s
• Fermentation (anaerobic) = 4 ATP’s