Photosynthesis part one: light reaction

Light Sunlight that we can see is referred to as the visible spectrum. Light is more than our human eyes can detect.Sunlight that we can see is referred to as the visible spectrum. Light is more than our human eyes can detect. The colors we see are what is reflected. What we don’t see is absorbed.The colors we see are what is reflected. What we don’t see is absorbed. The visible spectrum - rain drops acting as a prism.

Light and energy Light varies in frequency and wavelengthLight varies in frequency and wavelength Light wavelengths that are shortest have more energy.Light wavelengths that are shortest have more energy. Purples and blues contain most energy.Purples and blues contain most energy. Reds contain least energy.Reds contain least energy. The visible spectrum

Chlorophyll A Chlorophyll A is the primary plant pigmentChlorophyll A is the primary plant pigment Pigments are capable of absorbing light waves.Pigments are capable of absorbing light waves. Colors not absorbed are reflected. This is why plants are green.Colors not absorbed are reflected. This is why plants are green. Wavelengths of light chlorophyll absorbs. Pair share: what does chloro and phyll mean (hint look on “Greek to me” handout)

Other pigments Plants use additional pigments to absorb additional light.Plants use additional pigments to absorb additional light. Accessory pigments:Accessory pigments: –Chlorophyll B –Carotenoids Accessory pigments and the colors they absorb. Pair share: why do plants turn from green to red/ orange in the fall?

Light Dependent Reaction Occurs in the thylakoid membranes of chloroplast.Occurs in the thylakoid membranes of chloroplast. Energy source is sun light.Energy source is sun light. Uses water as a raw material.Uses water as a raw material. Products of light reaction will be used in the Calvin cycle later. (light independent reaction.)Products of light reaction will be used in the Calvin cycle later. (light independent reaction.) 6H 2 O + 6 CO 2 C 6 H 12 O 6 + 6O 2

Light Dependent Reaction photosystems are clusters of chlorophyll and other light collecting pigments.photosystems are clusters of chlorophyll and other light collecting pigments. Pigment molecules absorb light & their electrons become “excited”.Pigment molecules absorb light & their electrons become “excited”. Excited electrons are passed to primary electron acceptor.Excited electrons are passed to primary electron acceptor. Light reaction as diagramed

Using the energy in electrons Water is split Oxygen is releasedOxygen is released NADP+ is made into NADPHNADP+ is made into NADPH –ATP is made by process called chemiosmosis Thylakoids membranes & grana

Product summary of Light Reaction –ATP becomes energy source for Calvin cycle. –NADPH is source of hydrogen for making glucose. –Oxygen is a waste product released. Chlorophyll molecule

White board Review 1.Why do we see chlorophyll A as green? 2. Where does the light dependent reaction take place in the chloroplast? 3.Name 3 products of the light reaction.