Light absorption in chloroplasts

light reactions-initial reactions in photosynthesis
	absorption of light in chloroplasts
Chloroplasts
	site of photosynthesis
	ONLY 3-membrane organelle
		outer
		inner
		thylakoid
	thylakoids
		"junior mints"
		membrane bound, interconnected sacs
		site of light reactions
		chlorophyll is embedded in the thylakoid membrane	
	granum- stacks of thylakoids
	stroma
		"cytoplasm" around thylakoids
		site of dark reaction
		contains reactants and enzymes for the dark reaction	
Pigments- any substance that can absorb (light) energy
	most pigments absorb only SOME colors
Chloroplast pigments
	chlorophylls
		greens
		central metal is magnesium (Mg)
		fat soluble (embedded in thylakoid membrane)
		4 types
			A
				most common
				absorbs less blue, more red
			B
				bit less common
				absorbs more red, less blue
				assists in capturing light
			C
				not common
			D
				least common
	Accessory pigments
		enable plants to capture more light energy
		carotenoids(carotenes)
			yellow, orange, brown
		xanthophylls
			yellows, golds

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