The Cell
Photosynthesis & Respiration
Dr. ChildsScience Computer Lab
Spring, 2004
Energy
• Energy is “the ability to do work”
• Energy can neither be created nor destroyed.
• Energy can be converted from one form to another.
Types of Energy
• Heat or thermal• Solar or radiant• Mechanical• Electrical• Light• Sound• Chemical
•Energy can be converted from one form to another
Light bulb
electric → light
Fan
electric → mechanical
Power plant
mechanical (turbine) → electrical
firecrackers
chemical → sound & light
candle
chemical → light & heat
engine
chemical (gasoline) → mechanical
•Energy can be converted from one form to another
Solar energy
chemical energy –sugars
Photosynthesis
•Energy can be converted from one form to another
chemical energy –sugars
Electrical (nerve impulses)
sound
mechanical
Heat (Body temp = 98.6°)
Chemical (fat)
light
Energy in an Ecosystem
Energy Cycle in an Ecosystem
O2 + sugars + stored energy
CO2 + water + released energy
Heat
Ecosystem
Photosynthesis
Cellular respiration
Photosynthesis & Respiration
Type of Nutrition
Two types of nutrition:
• autotrophs – capture energy from sun
• heterotrophs - energy from food
AutotrophsProduce their own foods
• Photosynthesis – capture energy from sunlight• Produce sugars from CO2 and water.• Energy is stored as chemical energy in the bonds• Producers in food webs
Heterotrophs
Food from other sources
• Respiration – break down sugars, release energy• Consumers in food web• Animals, fungi, most protista
Photosynthesis
Photosynthesis
• The production of sugars from CO2 and water.
• Energy for the reaction comes from sunlight
• Energy is stored as chemical energy in the bonds of sugars.
• Occurs in chloroplasts
Photosynthesis
6126222 OHC O 0H CO
CO2
H2O
O2
C6H12O6
carbon dioxide
water
oxygen
sugar
Plant Cell & ChloroplastCross-section of leaf Plant cell
chloroplast
Photosynthesis
Photosynthesis occurs in the membranes of chloroplasts. The pigment, chlorophyll, is the site of energy capture from the sunlight.
GlucoseThe central molecule in energy metabolism is glucose (C6H12O6).
Glucose is synthesized in photosynthesis from CO2 and H2O. Energy is stored in the bonds.
Glucose is broken down in cellular respiration into CO2 and H2O. As bonds are broken, energy is released.
6126 OHC
ATPEnergy in the cell is stored in ATP.
Think of ATP as a battery. The low energy form is ADP (a dead battery). As the battery is charged, the high energy molecule, ATP, is formed.
ATP is created from ADP as the energy from respiration is released. The energy in ATP powers most cellular processes such as movement or enzyme reactions used the energy in ATP.
The energy is stored in high-energy phosphate bonds.
Respiration in Mitochondria
Cellular respiration occurs in mitochondria of cells.
Respiration
OH CO O OHC 2226126
CO2
H2OO2
C6H12O6
carbon dioxide
water
oxygen
Sugar - glucose
ATPhigh energy molecule
ADPlow energy molecule
Fermentation
• Fermentation involves the breakdown of glucose and the capture of energy by ATP without oxygen (anaerobic).
• The are two types of fermentation• alcoholic fermentation• lactic acid fermentation
Alcoholic Fermentation
Glucose → →
CO2
Ethanol
• End products are ethanol and CO2
Uses of Alcoholic Fermentation
•Yeast ferments sugars for bread (CO2 causes dough to rise)
•Alcoholic beverages
•Alternative fuel - gasohol
Lactic Acid Fermentation
Glucose → → Lactic Acid
• Anaerobic exercises burns more glucose than there is oxygen releasing lactic acid into the muscles.
• That why muscles hurt after a strenuous anaerobic exercise.• Results in “oxygen debt”.• Lactic acid is eventually broken down in the liver.
Weight lighting is anaerobic!!