Cell Energy
The ultimate source of energy for all
life is the sun.
Autotrophs are organisms that can
make their own food
ex. plants, algae, cyanobacteria
Cell Energy
Heterotrophs are organisms that
have to consume food to get energy
ex. animals, fungi
ATP (adenosine triphosphate)
ATP is the form of energy used by
cells
3 parts:
1. adenine
2. ribose sugar
3. three phosphate groups
ATP
Energy is stored in the bond between the
2nd and 3rd phosphate group.
What molecule is made when the energy
is released from the ATP?
ADP
Photosynthesis
6CO2 + 6H2O + light  C6H12O6 + 6O2
carbon dioxide + water + light  glucose + oxygen
What kind of organisms carry out
photosynthesis?
autotrophs
Photosynthesis
Autotrophs have pigments –
molecules that trap specific
wavelengths of light
Examples:
Chlorophyll
Carotene
Xanthophyll
Photosynthesis
Where in the cell does
photosynthesis take place?
Chloroplast
Light Reactions
(light-dependent reactions)
Where does it happen?
thylakoid membrane
What goes in?
light & water
What comes out?
oxygen, ATP, electron carriers
Calvin Cycle (light-independent or
dark reactions)
Where does it
happen?
stroma
What goes in?
CO2, ATP,
electron carrier
What comes out?
glucose sugar
Cellular Respiration
6O2 + C6H12O6  6CO2 + 6H2O + energy
oxygen + glucose  carbon dioxide + water + ATP
This is an aerobic process which
means
it requires oxygen
3 stages of aerobic respiration
Step 1: Glycolysis
Starts with
glucose
Produces
ATP, electron
carrier, & pyruvate
Occurs in
cytoplasm
3 stages of aerobic respiration
Step 2: Krebs cycle
(citric acid cycle)
 Starts with
pyruvate (changed to
acetyl-CoA)
 Produces
CO2 , ATP, &
electron carriers
3 stages of aerobic respiration
Krebs cycle cont.
Occurs in
matrix of the
mitochondria
3 stages of aerobic respiration
Step 3: Electron
Transport Chain
Starts with
electron carriers &
oxygen
3 stages of aerobic respiration
Produces
water & ATP
 Occurs on
inner
membrane
3 stages of aerobic respiration
Fermentation
This happens when NO oxygen is
present.
This is anaerobic, meaning . . .
no oxygen is required
Alcoholic Fermentation
Occurs in
cytoplasm of bacteria & yeast
Starts with
pyruvate (from glycolysis)
Produces
ethyl alcohol & carbon dioxide
Uses:
makes alcohol & bread
Lactic Acid Fermentation
Occurs in
cytoplasm of muscle cells & bacteria
Starts with
pyruvate (from glycolysis)
Produces
lactic acid
Lactic Acid Fermentation
Causes . . .
burning sensation after vigorous
exercise
Uses:
makes sauerkraut & yogurt