Biology
Class Notes
4-1
Topic: Photosynthesis and Respiration
Aim: How do organisms obtain and use energy?
Energy—the ability to do work
**What do we need energy for?**
(A)
AUTOTROPHS/HETEROTROPHS
 Energy comes from food
 The energy in most foods comes from the sun
 Organisms need energy to carry out all life processes
 Cells use energy for growth and repair, active transport, reproduction,
synthesis of compounds, etc
 Autotrophs- organisms that use energy from the sun to make food;
plants
 Heterotrophs—get energy from the foods they consume
 **to live, all organisms must release the energy found in compounds
(B)
CHEMICAL ENERGY
 energy is stored in chemical compounds
 ATP: chemical compound that stores and releases energy
 Adenosine triphosphate
 ADP (adenosine diphosphate) is formed when one phosphate group is
releases, giving off energy
 ATP—made up of adenine—ribose—3 phosphate groups
 ADP—made up of adenine—ribose—2 phosphate groups
 ATP has more energy than ADP
(C)
1)
2)
3)
4)
USING BIOCHEMICAL ENERGY
 Carry out active transport
 Produce movement
 Synthesis of proteins
 Produce light
 1 ATP—30 seconds of activity
 Sugar can store 90x the chemical energy of ATP
What is the ultimate source of energy for plants?
What is ATP and what does it do in the cell?
Draw and label an ATP molecule.
Name one cellular activity that uses the energy from ATP.