1. Energy and Life 8-1

2. Energy Energy is the ability to do work
Work can be playing a sport, thinking, or building a protein in a cell
All living things obtain and use energy

3. Autotrophs and Heterotrophs
Autotrophs: organisms that use light energy from the sun to make food
Organisms that do photosynthesis or something similar to obtain energy
Examples: plants and algae

4. Autotrophs and Heterotrophs
Heterotrophs: organisms that obtain energy from the food they consume
Organisms dependent on consuming other organisms for food
Examples: animals (us ) and fungi

5. Chemical Energy and ATP
Energy comes in many forms
Examples: light, heat, electricity, kinetic energy, potential energy
Most energy used in living systems comes from breaking chemical bonds

6. Chemical Energy and ATP
ATP (Adenosine Triphosphate): chemical compound living things use to store and release energy

7. Chemical Energy and ATP
ATP structure:
Adenine
3 phosphate
groups
Ribose

8. Chemical Energy and ATP
Energy is stored in the bonds between the phosphate groups
Energy is released when the bonds between the second and third phosphate is broken
Energy!

9. Chemical Energy and ATP
The resulting molecule is called ADP
Adenosine Diphosphate
It can have phosphate groups re-attached to be used again
Energy!

10. Chemical Energy and ATP
Cells keep a lot of ADP on hand
When energy becomes available cells store it by adding a third phosphate to an ADP
Making ATP
When a cell needs to do work the third phosphate is broken off, releasing energy

11. Using Biochemical Energy
Most energy in a cell is used for active transport
Also used for protein synthesis, contracting muscle cells, etc.
All life processes

12. Using Biochemical Energy
Cells keep a small supply of ATP on hand
Cells regenerate ATP from ADP using energy in food molecules like glucose
Done by mitochondria

13. Using Biochemical Energy
A single glucose molecule contains 90 times more energy than an ATP molecule
Jobs done in a cell require tiny amounts of energy
We couldn’t consume enough food to maintain life if a glucose molecule were consumed for each cellular job

14. Using Biochemical Energy
Making ATPs from glucose is like “making change”
Similar to having 100 $1 bills instead of a $100 bill if all you need is a candy bar