Energy of Life

Energy the ability to do work Where does your energy come from? Autotrophs - use energy from the sun to produce food. Heterotroph - get energy from the food they eat Forms of Energy light heat electricity

Energy Compounds Adenosine Triphosphate or ATP 3 Phosphate Groups Energy powers active transport, protein synthesis, & muscle contractions

break off a phosphate, energy is released Storing Energy ATP = ADP + 1 Phosphate fully charged battery Releasing Energy break off a phosphate, energy is released

Photosynthesis Introduction

Photosynthesis Introduction Jan van Helmont - measured plant’s water intake plants gain most of their mass from water

Photosynthesis Introduction Priestley : took a candle and placed a glass jar over it watched the flame gradually die out something in the air was necessary to keep the candle burning: oxygen

Photosynthesis Introduction Priestly’s Second Experiment placed a live spring of mint under the jar and allowed a few days to pass the candle would remain lite a while. Why? mint plant produced oxygen.

Photosynthesis Introduction Jan Ingenhousz - aquatic plants produce oxygen bubbles in the light, but not in the dark plants need sunlight to produce oxygen.

Photosynthesis plants use energy of sunlight to covert water and carbon dioxide into high-energy carbohydrates: sugar & starches oxygen: waste product Photosynthesis Equation 6CO2 + 6H20 + (light)  C6H12O6 + 6O2 carbon dioxide + water + (light)  sugars + oxygen

Light and Pigments

Light Energy Energy travels to the Earth in the form of light. White light: mixture of different wavelengths/colors

Principle Pigment: chlorophyll Plants gather the sun’s energy with light absorbing molecule called pigments Principle Pigment: chlorophyll which is in the chloroplast chlorophyll a & chlorophyll b Chlorophyll absorbs light well: blue-violet, chlorophyll b red region, chlorophyll a green light is reflected by leaves

Secondary Pigment: Carotene absorbs light in the red & orange region leaves turn red, yellow, and orange in the fall

Light  Energy When chlorophyll absorbs light, it absorbs energy Energy is transferred to the electrons in the chlorophyll molecule Allows photosynthesis to work

Reactions of Photosynthesis

Chloroplast In the chloroplast, thylakoids are in stacks called grana Thylakoid organize chlorophyll and other pigments into photosystem. Photosystems: light collecting units of the chloroplast  

Photosynthesis Light dependent reaction Thylakoid membrane Light independent reaction or Calvin Cycle Stroma: region outside of the thylakoid membrane

Electron Carriers electrons gain energy when excited by sunlight high-energy electrons are transported by electron carriers electron carriers are called the Electron Transport Chain

Electron Carriers NADP+ - carrier that holds 2 high-energy electrons and H+ ion NADP+  NADPH NADPH carries the high-energy electrons throughout the cell High energy electrons are used to build carbohydrates, like glucose

Electron Transport

Light-Dependent Reaction Occurs in the thylakoid membrane uses energy from light ADP  ATP NADP+  NADPH produces O2 gas

Calvin Cycle Occurs in the stroma: region outside the thylakoid membrane Uses ATP and NADPH to build high energy sugars long term energy storage does not require light

Factors Affecting Photosynthesis Water shortage: slows photosynthesis Plants in dry conditions have waxy coating to reduce water loss Temperature: 0-35ºC Above or below damages enzymes and photosynthesis slows Light: rate increases with intensity Maximum exists