8.2 The Light reactions convert light energy to chemical energy

=8.2 The light reactions convert light energy to chemical energy=

*Vocab

-wavelength=>distance between adjacent waves

-electromagnetic spectrum=> range of types of electromagnetic energy from gamma waves to radio waves

-pigment=>chemical compound that determines a substance's color

-paper chromatography=> laboratory technique used to observe the different pigments in a material

-photosystem=>cluster of chlorophyll and other molecules in a thylakoid

*Light Energy and Pigments

-Sunlight: form of electromagnetic energy

gamma rays-X-rays-UV-visible light-infrared-microwaves-radiowaves

>Pigments and Color

pigment choose the color of a substance

-three things happens to different wavelengths when it shines an object->absorbed, tranmitted, or reflected

-If a color is green, it is green because green is reflected from the object and other color is absorbed

>Identifying Chloroplast pigments

-We can observe different pigments in a green leaf by using laoratory tech called paper chromatography

-paper chromatography can separate and analyze the pigments in a leaf

*Harvesting Light energy

-We can watch the process occuring in a chloroplast as sunlight strikes a leaf.

-photosystems contains pigment molecules-the solar collectors

-Pigment's electrons gains energy as pigment molecules absorbs light energy

-chlorophyll a molecule get trapped by primary electron acceptor to be used to make ATP and NADPH

*Chemical Products of the Light Reactions

-light strikes photosystem and transfer excited electrons to the primary electron acceptor.

-electrons split water and releases oxygen

-excited electron goes through electron transport chain and pumps H+ions across the membrane to thylakoid.

-light excited electrons get ransferred to NADP+

*Concept Check

1.Explain why a leaf appears green

-leaf appears green because it reflects green light and absorb the other light colors

2.Describe what happens when a molecule of chlorophyll a absorbs light.

-when a molecule of chlorophyll a absorbs light it gets trapped by primary electron acceptor to produce ATP and NADPH.

3.Besides oxygen, what two molecules are produced by the light reactions?

-ATP & NADPH

4.Where in the chloroplast do the light reactions take place?

-It takes place in the thylakoid membrane