cells capture and release energy section 2.2. energy energy is needed by organisms to stay alive –...

Cells Capture and Release Energy

Section 2.2

Energy

Energy is needed by organisms to stay alive–Plants get energy from the sun–Animals get energy from food

Energy

Chemical energy is stored in the bonds of molecules –Cells need to break the bonds of molecules

to release energy–Glucose is a major energy source of cells

Energy

Photosynthesis– Plants take energy from the sun and change it to

the chemical energy in glucose– The process takes place in cell with chloroplasts– Chlorophyll, a light absorbing pigment, traps the energy from sunlight

Energy

Photosynthesis sunlight

CO2 + H2O C6H12O6 + O2

Chlorophyll

Some glucose is changed to starch and stored for later use

Energy

Energy is released from food when the chemical bonds are broken

Cellular Respiration– Cells use oxygen to release stored energy in sugar– Takes place in the mitochondria– Takes place in animals and plants

Energy

Cellular Respiration

C6H12O6 + O2 H2O + CO2 + Energy

– Some energy is transferred to other molecules which carry energy to where it is needed

– The rest of the energy is released as heat

Energy

Fermentation–Cells release energy without oxygen–Cells break glucose down into smaller

molecules and release small amounts of energy– Small molecules ferment in cytoplasm–Alcoholic fermentation (bread) or lactic acid

fermentation (yogurt, cheese) can occur

Energy

Exercise– Muscles store energy and oxygen– During long exercise, muscles use up energy– Fermentation occurs to provide energy and lactic

acid builds up (burning)– You breathe hard to break down byproducts

fermentation (burning goes away)– Reserves of energy an oxygen build up again

Energy

Energy

Energy