10/13/2013
Types of Energy
Chemical Energy and
ATP
Date: _________
Laws of Thermodynamics
• First law
–Energy can be converted from
one form to another, but it can
NEVER be CREATED or
DESTROYED
• Second law
–Any time energy is converted
from one form to another, some
energy is lost (usually as heat)
• Chemical
• Nuclear
• Radiant
• Mechanical
• Electric
• Thermal
• Magnetic
• Sound
Potential
Kinetic
How do living things obtain energy?
• All organisms need energy to live.
• Autotrophs
– Organisms that make their own food –
usually from the sun, like plants
– Chemoautotrophs use inorganic
substances like hydrogen sulfide as a
source of energy
• Heterotrophs
– Need to ingest food to obtain energy
– Eat autotrophs or other heterotrophs,
stores energy as ATP
Metabolism
Energy Trade-Off
• Metabolism: all of the chemical reactions in a cell
• Metabolic pathways: series of chemical reactions
in which the PRODUCT of one reaction is the
REACTANT for the next reaction
– Catabolic pathways: release energy by
breaking down larger molecules into smaller ones
– Anabolic pathways: use energy released
to build larger molecules from smaller
ones
• Energy continually flows between catabolic and
anabolic pathways
• Photosynthesis is an ANABOLIC pathway in which
light energy from the sun is converted to
chemical energy (sugar) for use by the cell
• Cellular respiration is the
CATABOLIC pathway in which
organic molecules (sugar) are
broken down to release energy
for use by the cell
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10/13/2013
The Cell’s Energy Molecule
• Adenosine triphosphate: the most
important biological molecule that gives
the cell energy.
• One molecule of ATP consists of
ATP Molecule
–Nitrogenous base called adenine
–Ribose sugar
–Three phosphate groups
• High-energy bonds connect the three
phosphate groups
ATP is like a Battery
ATP-ADP Cycle
• It can be recharged!
• When ATP is used, the last phosphate molecule
is detached when the high-energy bond is
broken
ATP
– This creates ADP – adenosine diphosphate
• In order to constantly supply
the cell with energy, ADP is
recycled to create ATP again
– Another phosphate molecule
is added back to the ATP
energy is
stored
high-energy
bond is broken
energy is used
(released)
ADP
Focus Questions
1. What is the difference between kinetic and
potential energy?
2. Can energy be created? Destroyed?
3. What is an autotroph? A heterotroph?
4. Where does all energy on Earth come from?
5. What is metabolism?
6. What happens during a catabolic reaction?
Anabolic reaction?
7. What is ATP? What does it stand for?
8. When ATP is used, what is it converted to?
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