logo

BioFlix: The Light Reactions

by Pearson
5 views
Was this helpful ?
0
Zooming into a chloroplast we see these flattened membranous sacks called thylakoids Here light energy is converted to chemical energy in the first phase of photosynthesis, the light reactions The two green structures you see here are photo systems Large complexes of proteins and chlorophyll that captures light energy An electron transport chain connects the two photo systems Notice the small mobile electron carriers that shuttle electrons from one large complex to another Now let's take a close look at the steps of the light reactions The photos system on the left absorbs light energy exciting electrons that enter the electron transport chain Electrons are replaced with electrons stripped from water creating oxygen as a byproduct The energized electrons flow down the electron transport chain releasing energy that is used to pump hydrogen ions, the blue balls into the thylakoid In the photo system on the right light energy excites electrons and this time the electrons are captured by an electron carried molecule NADPH The high concentration of hydrogen ions inside the thylakoid powers ATP synthase producting ATP's The light reactions in the thylakoid have produced two energy products ATP and NADPH that will now power the production of sugar in the Calvin cycle
Zooming into a chloroplast we see these flattened membranous sacks called thylakoids Here light energy is converted to chemical energy in the first phase of photosynthesis, the light reactions The two green structures you see here are photo systems Large complexes of proteins and chlorophyll that captures light energy An electron transport chain connects the two photo systems Notice the small mobile electron carriers that shuttle electrons from one large complex to another Now let's take a close look at the steps of the light reactions The photos system on the left absorbs light energy exciting electrons that enter the electron transport chain Electrons are replaced with electrons stripped from water creating oxygen as a byproduct The energized electrons flow down the electron transport chain releasing energy that is used to pump hydrogen ions, the blue balls into the thylakoid In the photo system on the right light energy excites electrons and this time the electrons are captured by an electron carried molecule NADPH The high concentration of hydrogen ions inside the thylakoid powers ATP synthase producting ATP's The light reactions in the thylakoid have produced two energy products ATP and NADPH that will now power the production of sugar in the Calvin cycle