Energy in a Cell
All Cells Need Energy
Cells need energy to:
– Make new molecules.
– Build membranes and organelles.
– Move molecules in and out of the
cell.
– Move.
Autotrophs (producers)
 Organisms that make their own food
 Use light energy from the sun to make food
Example: PLANTS
Heterotrophs (consumers)
 Organisms that get energy from the
foods they eat
Example: ANIMALS
NOT a flashcard.
Where Does A Cell Get Energy?
Food is broken down to a form
the cell can use.
Extra energy is stored in an ATP
molecule.
ATP
Adenosine triphosphate is a
molecule made up of
– adenine
– ribose
– 3 phosphate groups.
Adenine
Ribose
(ENERGY
STORED HERE!)
ADP
 Adenosine diphosphate. Made up of
– adenine
– ribose
– 2 phosphate groups.
Adenine
Ribose
How Does ATP Work?
 Energy is stored in the bond between
the second and third phosphate group.
 When the bond is broken, energy is
released and ADP is formed.
Adenine
Ribose
Storing Energy
 Energy is stored by the cell when 1
Adenine
phosphate is added to the end of an
ADP molecule forming ATP.
Ribose
Adenine
Ribose
2 Ways to make ENERGY!
1. Photosynthesis – takes place in
the chloroplasts.
2. Cellular Respiration – takes place
in the mitochondria.
Photosynthesis
 Autotrophs make their own food by
trapping light energy and converting it to
carbohydrates.
Equation:
6CO2 + 6H2O + sunlight
C6H12O6 + 6O2
NOT a flashcard.
Plants produce O2 gas by
splitting water
The O2 released by photosynthesis is
made from the oxygen in water.
6CO2 + 6H2O + sunlight
C6H12O6 + 6O2
Cellular Respiration
The process of breaking down
food molecules to release
energy.
Occurs in the mitochondria.
Equation:
C6H12O6 + 6O2
6CO2 + 6H2O + ENERGY
NOT a flashcard.
Compare The Equations!
 Photosynthesis:
6CO2 + 6H2O + sunlight
C6H12O6 + 6O2
 Cellular Respiration:
C6H12O6 + 6O2
6CO2 + 6H2O + ENERGY
Two Types of Respiration
Aerobic Respiration– requires
oxygen.
Anaerobic Respiration– requires
an absence of oxygen.
The End
 Any questions? 
Anaerobic Respiration
 Two types:
– Fermentation – occurs when bacteria
break down plants (vegetables and
fruit) and release alcohol or vinegar.
– Lactic Acid Fermentation – occurs in
muscles – a buildup of lactic acid
causes soreness.
NOT a flashcard.
Sunlight
Heat
Photosystem
II
NADP+
ADP
O2
PhotoSystem
I
ATP
H2O
NAD+
NADPH
ATP
NADH
CO2
Calvin
Cycle
Glycolysis
Glucose
CHLOROPLAST
Electron
Transport
System
Citric
Acid
Cycle
ATP
Pyruvate
ATP
MITOCHONDRIA
Chemosynthesis
Some autotrophs can convert
inorganic substances to energy.
Most are adapted to live in conditions
where there is no oxygen.
– Digestive tracts of mammals
– Lake sediments
– Marshes
– Deep in the ocean
NOT a flashcard.
The End
 Any questions? 
NOT a flashcard.
Photosynthesis in a picture!