Photosynthesis Flashcards
Photosynthesis
The process by which light energy is converted to chemical bond energy and carbon is fixed into organic compounds. (6CO2 + 12H2O = C6H12O6 + 6H2O + 6O2)
Two Processes of Photosynthesis
Light-Dependent/Light Reactions and Light-Independent Reactions
Photosynthesis: Light Reactions
Reactions that use light energy directly to produce ATP that powers the light-independent reactions. Light must be present for this reaction to occur.
Photosynthesis: Light-Independent Reactions
Reactions that consist of the Calvin cycle which produces sugar. To power the production of sugar, the Calvin cycle uses the ATP produced by the light reactions. This reaction only occurs when light is present.
Photosynthesis: Light-Independent Reactions
Reactions that consist of the Calvin cycle which produces sugar. To power the production of sugar, the Calvin cycle uses the ATP produced by the light reactions. This reaction only occurs when light is present.
Photosynthetic Pigments
Absorb energy and use it to provide energy to carry out photosynthesis. Two major groups: chlorophylls and carotenoids.
Photosynthetic Pigments: Chlorophyll
Chlorophyll a and chlorophyll b are green and absorb red, blue, and violet range lengths of light waves.
Photosynthetic Pigments: Cartenoids
They are yellow, orange and red. They absorb light in the blue, green and violet range.
Photosynthetic Pigments: Xantholophyll
A carotenoid with a slight chemical variation.
Photosynthetic Pigments: Phycobilins
Found in red algae; are reddish and absorbs light in the blue and green range.
Antenna Pigments
Chlorophyll b, the carotenoids, and the phycobilins are known by this name because they capture light in wavelengths other than those captured by chlorophyll a. They also absorb photons of light and pass the energy along to chlorophyll a.
Photosynthetic Pigments: Chlorophyll A
Directly involved in the transformation of light energy to sugars.
Chlorophyll A: Structure
It’s a large molecule with a magnesium atom in the head surrounded by alternating double and single bonds. The head, called the porphyrin ring, is attached to a long hydrocarbon tail. The double bonds play a critical role in the light reactions because they;re the source of the electrons that flow through the electron transport chains during photosynthesis.
Chlorophyll A: Structure
It’s a large molecule with a magnesium atom in the head surrounded by alternating double and single bonds. The head, called the porphyrin ring, is attached to a long hydrocarbon tail. The double bonds play a critical role in the light reactions because they;re the source of the electrons that flow through the electron transport chains during photosynthesis.
The Chloroplast: Structure
Contains grana, where light reactions occur, and stoma, where light-independent reactions occur. The grana consists of layers of membranes called thylakoids, the site of photosynthesis I and II. It is enclosed by a double membrane.
The Chloroplast: Structure
Contains grana, where light reactions occur, and stoma, where light-independent reactions occur. The grana consists of layers of membranes called thylakoids, the site of photosynthesis I and II. It is enclosed by a double membrane.
Photosystems
Light-harvesting complexes in the thylakoid membraned of the chloroplasts. There are a few hundred in each thylakoid.
Photosystems: Structure
Consists of a reaction center containing chlorophyll a and region contain several hundred antenna pigment molecules that funnel energy into chlorophyll a.
Photosystems: PS I & PS II
PS II operates first followed by PS I. PS I absorbs light best in the 700nm range (it is also called P700). PS II absorbs light in the 680nm range (it is also called P680).
Light Reaction Process Overview
Light is absorbed by PS I and PS II in the thylakoid membranes and electrons flow through the electron transport chain. Afterwards, there are two possible routes for electron flow: noncyclic and cyclic photophosphorylation.