Introduction to Cellular Energy

Energy! Energy! Everyone needs it. Why? Where does almost all of the energy for living systems come from? The SUN! Autotrophs (producer) - create their own organic material Heterotrophs (consumer) – consume/eat their organic material

Photosynthesis The main process used by autotrophs 6H 2 O +6CO 2 + sunlight  C 6 H 12 O 6 + 6O 2 It end goal is to produce organic material (C 6 H 12 O 6 ) some of which will be used as food; much of which will be used as building materials for the autotroph There are two steps ▫Light reactions/light dependent reactions – transforms the sunlight into usable energy ▫Calvin cycle/light independent reactions/dark reactions – using the energy from step 1, it will create organic materials from CO 2

Chloroplast Found in plants, algae, and some protist Two membranes Inside the second membrane is a set of membranes called the thylakoids. Stacks of thylakoids are called grana Surrounding the grana is a fluid called the stroma Believed to be the second organelle formed

Pigments The chloroplast contains chlorophyll Chlorophyll a – absorbs red light Chlorophyll b – absorbs blue light Neither absorbs much green Chlorophyll a directly absorbs the sunlight for the light reactions. Chlorophyll b assists. Chlorophyll is very abundant in the leaves, hence why they are green. Chlorophyll break down in the fall which is why plants turn shades of reds and yellows. They only have carotenoids left.