Transcript
Page 1: Photosynthesis The Flow of Energy. ATP  adenosine triphosphate  chemical compound used by living things to store energy  When the bond between two

Photosynthesis

The Flow of Energy

Page 2: Photosynthesis The Flow of Energy. ATP  adenosine triphosphate  chemical compound used by living things to store energy  When the bond between two

ATP adenosine triphosphate chemical compound used by living

things to store energy When the bond between two

phosphate groups is broken – energy is released

ATP ADP + Pi

Page 3: Photosynthesis The Flow of Energy. ATP  adenosine triphosphate  chemical compound used by living things to store energy  When the bond between two

Photosynthesis Jan van Helmont – plants gain their

mass from water Joseph Priestly – plants release oxygen

Jan Ingenhousz – light is necessary for plants to produce oxygen

6CO2 + 6H2O C6H12O6 + 6O2

Page 4: Photosynthesis The Flow of Energy. ATP  adenosine triphosphate  chemical compound used by living things to store energy  When the bond between two

Light Visible spectrum – ROYGBIV Red = longest wavelength Violet = shortest

wavelength Color of an object

is determined by

the color the object reflects Plants gather light using pigments

Page 5: Photosynthesis The Flow of Energy. ATP  adenosine triphosphate  chemical compound used by living things to store energy  When the bond between two

Chloroplasts and Pigments

chloroplast – organelle where photosynthesis occurs– chlorophyll – a green pigment, most

important in photosynthesis– carotenoids – yellow, orange and red

pigments absorbed light is transformed from

light energy to chemical energy

Page 6: Photosynthesis The Flow of Energy. ATP  adenosine triphosphate  chemical compound used by living things to store energy  When the bond between two

Inside a Chloroplast thylakoids – saclike

photosynthetic membranes

grana – stacks of thylakoids

stroma – space outside the thylakoids

Page 7: Photosynthesis The Flow of Energy. ATP  adenosine triphosphate  chemical compound used by living things to store energy  When the bond between two

Overview of Photosynthesis

photosynthesis occurs only in producers endergonic reaction – a chemical

reaction that uses or stores energy Two steps of photosynthesis

– Light Reactions– Calvin Cycle

Page 8: Photosynthesis The Flow of Energy. ATP  adenosine triphosphate  chemical compound used by living things to store energy  When the bond between two

Light Reactions require light use energy from light to produce ATP

and NADPH occurs in the grana energy from “excited electrons” is used

to bond ADP and Pi to form ATP

Page 9: Photosynthesis The Flow of Energy. ATP  adenosine triphosphate  chemical compound used by living things to store energy  When the bond between two

Light Reactions 3 main events

– Light energy is absorbed by the chlorophyll and ATP is made

– Water is split into hydrogen ions, oxygen and electrons

– The hydrogen ions are used to make NADPH

Page 10: Photosynthesis The Flow of Energy. ATP  adenosine triphosphate  chemical compound used by living things to store energy  When the bond between two

Light Reactions Inputs:

– Light– Water

Outputs:– ATP – NADPH

– Oxygen (O2)

Page 11: Photosynthesis The Flow of Energy. ATP  adenosine triphosphate  chemical compound used by living things to store energy  When the bond between two

Calvin Cycle

Also called the dark reactions or light-independent reactions

process of synthesizing sugars occurs in the stroma does not require light converts CO2 to sugar

Page 12: Photosynthesis The Flow of Energy. ATP  adenosine triphosphate  chemical compound used by living things to store energy  When the bond between two

Calvin Cycle 3-carbon sugars are produced

– Some used as energy sources– Some converted to lipids, amino acids,

parts of nucleic acids– Two can combine to form 6-carbon

sugars

Page 13: Photosynthesis The Flow of Energy. ATP  adenosine triphosphate  chemical compound used by living things to store energy  When the bond between two

Calvin Cycle Inputs:

– ATP– NADPH

– CO2

Outputs:– Sugars

Page 14: Photosynthesis The Flow of Energy. ATP  adenosine triphosphate  chemical compound used by living things to store energy  When the bond between two

In the end… a single 6-carbon sugar is formed from

6 molecules of carbon dioxide plants use the sugar for energy and to

build more complex carbohydrates such as starches and cellulose

other organisms eat the plants and use the energy stored in carbohydrates

Page 15: Photosynthesis The Flow of Energy. ATP  adenosine triphosphate  chemical compound used by living things to store energy  When the bond between two

Factors Affecting Photosynthesis

Shortage of water– Can slow or stop photosynthesis

Temperature– Photosynthesis requires enzymes that

function best between 0°C and 35°C Intensity of light

– Increasing light intensity increases the rate of photosynthesis


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