The Cell Photosynthesis & Respiration Dr. Childs Science 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 O 2 + sugars + stored energy CO 2 + 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

Autotrophs Produce their own foods Photosynthesis – capture energy from sunlight Produce sugars from CO 2 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 The production of sugars from CO 2 and water. Energy for the reaction comes from sunlight Energy is stored as chemical energy in the bonds of sugars. Occurs in chloroplasts

Photosynthesis CO 2 H2OH2O O2O2 C 6 H 12 O 6 carbon dioxide water oxygen sugar

Plant Cell & Chloroplast Cross-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.

Glucose The central molecule in energy metabolism is glucose (C 6 H 12 O 6 ). Glucose is synthesized in photosynthesis from CO 2 and H 2 O. Energy is stored in the bonds. Glucose is broken down in cellular respiration into CO 2 and H 2 O. As bonds are broken, energy is released.

ATP Energy 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 CO 2 H2OH2O O2O2 C 6 H 12 O 6 carbon dioxide water oxygen Sugar - glucose ATP high energy molecule ADP low 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 → → CO 2 Ethanol End products are ethanol and CO 2

Uses of Alcoholic Fermentation Yeast ferments sugars for bread (CO 2 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!!