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• 6H2O +6CO2 + sunlight C6H12O6 +

6O2 • It end goal is to produce organic

material (C6H12O6) 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 CO2

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.