Cellular Respiration- A Chemical Reaction:
Cellular respiration is a chemical reaction that occurs in the mitochondria of cells.
During cellular respiration, organic molecules are broken down to release energy. The
process of cellular respiration occurs in both autotrophs and heterotrophs. Autotrophs make
their own chemical energy in the form of the organic molecule glucose. Heterotrophs
consume many different organic molecules that can be broken down for energy.
Let’s look at the chemical equation for Cellular Respiration:
Reactants:
Oxygen + Organic Molecule
O2
+
Inhale
C6H12O6
Products:
Carbon Dioxide + Water + ENERGY
CO2
+
H2O
+
ATP
Exhale
The reactant oxygen is obtained from the air. Oxygen diffuses into the cell across the cell
membrane to make its way to the mitochondria, the organelle where cellular respiration takes
place. Autotrophs obtain the organic molecule glucose by making it themselves in a process
called photosynthesis. Heterotrophs get organic molecules from other organisms by eating
them. The 4 macromolecules- proteins, carbohydrates, fats (lipids), and nucleic acids are all
organic!! Bread, pasta, vegetables, nuts, sugar, cheese, etc. ALL come from things that were once
living organisms and are all made from the macromolecules.
The reactants are then broken down by the mitochondria to make the products of
carbon dioxide, water, and ATP. Carbon dioxide and water are waste products, and leave the
organism. Animals exhale carbon dioxide and water into the air. The most important product
of cellular respiration is ATP. ATP is an energy molecule. It captures the energy released when
organic molecules are broken down. The ATP energy can then be used to power all cell
activities.
After the bonds between organic molecules have been broken down, the atoms and
elements still remain. These “Leftovers” can be used to synthesize new organic molecules that
the body may need. For example, an organism may break down proteins during cellular
respiration, but then use the ‘leftover’ elements to put together a lipid needed by the cell
membrane. The process of building macromolecules is called biosynthesis. The breakdown
and buildup of molecules in living things is known as metabolism. Cellular respiration is a
metabolic process; organic molecules are broken down to release energy, and then are used
to build new materials.
Name:___________________________________________________________
Questions:
Class Period:__________
1. Where does cellular respiration occur?
2. What happens in cellular respiration?
3. How do heterotrophs get chemical energy?
4. How do autotrophs get chemical energy?
5. What are the reactants of cellular respiration?
6. What are the products of cellular respiration?
7. What are the 4 macromolecules?
8. Are the macromolecules organic? What 2 elements must they all contain?
9. What is ATP?
10. What happens to the products carbon dioxide and water?
11. What can cells do with the organic elements after the molecule has been broken down?
12. What is biosynthesis?
13. What is metabolism?