Energy of Life
Why do Cells Need Energy?
• To maintain homeostasis• For growth and
development• For the movement of
materials• For the building/breaking
down of molecules• To respond to their
environment
Cells use Chemical Energy
• Energy is stored in the bonds between atoms.
• Energy is released when those chemical bonds break.
ATP and ADP• Cells cannot use sugars for energy, so they must convert
them to a usable form - - - ATP.
• 1 glucose can break down and create 38 ATP molecules.
• This happens in the mitochondria.
ATP and ADP• Energy is stored in the bonds of ATP– Adenine– Ribose (sugar)– 3 phosphate groups
• Energy is released when ATP loses a phosphate group to form ADP.
• Human cells use about 125 pounds of ATP every day so the moleculesmust be recycled again and again.
ATP and ADP• Recap……..– ATP is adenosine triphosphate• It has stored energy like a charged battery
– ADP is adenosine diphosphate• It has less energy like a partially charged battery
Limits of ATP
– ATP is not good for storing energy for a long time.
– Glycogen, starch, glucose, fat, are better for long term storage.
How Do Organisms Get Energy ?
Autotrophscreate their own food
Photosyntheticconvert light to chemical energy
Chemosyntheticuse inorganic chemicals for energy
Ex: Plants, algae, archaebacteria
How Do Organisms Get Energy ?
Heterotrophs
must consume their food
Ex: Humans, other animals
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