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!!