Photosynthesis: Life from Light and Air

Energy needs of life All life needs a constant input of energy Animals = Heterotrophs get their energy from “eating others” eat food = other organisms = organic molecules make energy through respiration Plants = Autotrophs get their energy from “self” get their energy from sunlight build organic molecules (food) from CO2 make energy through photosynthesis

Carbon Dioxide + Water → Glucose + Oxygen Photosynthesis: the process that uses the sun’s energy to make simple sugars, such as glucose. 6CO2 + 6H2O → C6H12O6 + 6O2 Carbon Dioxide + Water → Glucose + Oxygen What are some sources of carbon dioxide for plants? Natural sources of atmospheric carbon dioxide include volcanic outgassing, the combustion of organic matter, and the respiration processes of living aerobic organisms; man-made sources of carbon dioxide include the burning of fossil fuels for heating, power generation and transport, as well as some industrial processes such as cement making. It is also produced by various microorganisms from fermentation and cellular respiration What are some sources of water for plants?

How do plants live? Photosynthesis Energy building reactions collect sun energy make ATP Sugar building reactions use ATP for energy use CO2 as carbon for new sugars build sugars glucose, cellulose, starch build all other organic molecules proteins, lipids, carbohydrates, DNA store energy for future use starch in seeds & roots

Energy building reactions Sugar building reactions Photosynthesis Energy building reactions Sugar building reactions sun ATP ADP CO2 sugar Actually 2 separate reactions Energy building use sunlight make energy (ATP) Sugar building use ATP use CO2 make sugars (C6H12O6)

Chloroplasts absorb sunlight & CO2 make energy & sugar Contain chlorophyll

Light-Dependent Reactions H2O + light energy  ATP + O2 H2O makes ATP energy releases oxygen as a waste product sunlight Energy Building Reactions ATP O2

Light-Independent Reactions sugars C6H12O6 CO2 Sugar Building Reactions ATP ADP CO2 +  ATP C6H12O6 + ADP builds sugars uses ATP cycles ADP back to make more ATP The first phase of photosynthesis requires light and is known as light-dependent reactions. Sunlight comes in and hits the chlorophyll the energy of light is transferred to electrons that are passed along the electron transport chain – which is a series of proteins embedded in the thylakoid membrane. The second phase of photosynthesis does not require light and is called many things including light-independent reactions, the dark reactions and the calvin cycle. These reactions take CO2 and the energy from the light reactions – in the form o fATP and NADPH – and produces sugar and oxygen.

Putting it all together CO2 H2O C6H12O6 O2 light energy  + H2O Plants make both: ATP sugars CO2 sunlight ADP Energy Building Reactions Sugar Building Reactions ATP sugars C6H12O6 O2

So what does a plant need? Bring In CO2 H2O light Let Out O2 Move Around sugars leaves shoot roots 6CO2 6H2O C6H12O6 6O2 light energy  +