Cell EnergyChapter 4 Section 2

Objectives:

• Describe photosynthesis and cellular respiration.

• Compare cellular respiration with fermentation.

Photosynthesis

• The energy that fuels life comes from the sun.

• Photosynthesis: the process that plants and algae use to convert light energy into food energy

• This food supplies energy for the plant as well as other organisms that eat the plant.

• Without plants (producers), consumers wouldn’t be able to live.

Photosynthesis

• Pigments: molecules in plants that absorb the energy from light– Example:

chlorophyll is a pigment (in chloroplasts) that gives plants their green color

Photosynthesis

6CO2 + 6H2O + light energy C6H12O6 + 6O2

Carbon Water Glucose Oxygen

Dioxide (Sugar)

Plants use energy from sunlight to change carbon dioxide and water into glucose

(food) and oxygen.

Cellular Respiration• Food has to be broken down into energy

that our cells can use.

• Respiration means “breathing”– But cellular respiration is not the same thing

as breathing

• Cellular Respiration: the process of producing energy (ATP) from Oxygen and Glucose (food)

• ATP (Adenosine Triphosphate): energy molecule the cell can use

Cellular Respiration

C6H12O6 + 6O2 6CO2 + 6H2O + energy (ATP)

Glucose Oxygen Carbon Water

Dioxide

Food and oxygen are broken down into carbon dioxide, water and ATP.

Most of the energy produced is in the form of heat.

This helps to maintain body temperature.

Cellular Respiration in Eukaryotes

• Takes place in mitochondria

Photosynthesis vs. Cellular Respiration

Photosynthesis Cellular Respiration

•Reactants: light energy, carbon dioxide, and water•Products: glucose and oxygen•Occurs in plant cells•Takes place in chloroplasts.

•Reactants: glucose and oxygen•Products: energy (ATP and heat), carbon dioxide, and water•Occurs in both plant and animal cells.•Takes place in mitochondria.

Fermentation

• Takes place when there isn’t enough oxygen to do cellular respiration.

• A small amount of ATP is made during fermentation.

C6H12O6 → 2 C2H5OH + 2 CO2

     sugar  -> ethanol + carbonic gas

2 Types of Fermentation

Type 1 Type 2

•Occurs in muscle cells, some fungi, and some bacteria.•Lactic acid & ATP is produced

–Causes muscle fatigue/ sore muscles

•Occurs in some bacteria and yeast.•ATP, Carbon dioxide, & alcohol are produced.

–Carbon dioxide bubbles are what cause bread to rise.