Introduction/Basic Info Photosynthesis

Essential for all life on earth Autotrophs Consumers Photosynthesis Glucose (only an example) Respiration CO 2

Photosynthesis So how do we actually see different colors? The wavelength of the light will determine the color of the light

Photosynthesis When light waves are absorbed from this region of the visible spectrum it can be used by a plant Green leaves look green because they have a pigment that does not absorb green light, it reflects it

Photosynthesis

The main light absorbing pigment in green plants is chrorophyll—found inside the chloroplasts Like a mitochondrion, the structure of the chlorophyll is directly related its function (common theme in bio) Have their on DNA in a ring, ribosomes (70S), an inner and outer membranes Only actual green structures in a plant

Photosynthesis starch granule Ribosomes in stroma Stoma lamellae

Photosynthesis Chlorphyll is a green pigment Reflects green wavelengths of light, in the middle of the VS, absorbs non-green wavelengths Blue and red regions are absorbed the most Absorption spectra show which wavelengths are absorbed as a function of O 2 production

Photosynthesis

Two stages of photosynthesis: light independent and light dependent Different sets of reactions used in each stage Light dependent produces ATP and allows photolysis to occur (O 2 is a waste product) Light independent allows for carbon fixation

Photosynthesis—Light dependent Chlorophyll, and other pigments, absorb light from the sun (or other source) Energy from absorbed wavelengths produces ATP Light also used to split water into H 2 and O 2 (photolysis) Released O 2 is source of aerobic respiration; ATP and H 2 used by the plant

Photosynthesis—Light dependent light water H+H+ O2O2 electrons H2H2 Chlorophyll and other photosynthetic pigments Light dependent reactions ATP ATP production very similar to that of respiration w/ most energy being acquired via an electron transport chain

ATP and H 2 generated from light dependent stage used to covert CO 2 and H 2 O into organic compounds (like glucose) This carbon fixation…turning inorganic to organic Fixation requires energy—all comes from sun Photosynthesis—Light independent 6CO 2 + 6H 2 OC 6 H 12 O 6 + 6O 2

Photosynthesis 6CO 2 + 6H 2 OC 6 H 12 O 6 + 6O 2 C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O RESPIRATION!!!! Plants do both…photosynthesis and respiration Respiration occurs at a slow, steady rate, regardless of light/dark = small yields of ATP. Why? No muscle, large movement, or other energy requiring processes…less ATP needed vs animals

Photosynthesis-rates Photosynthesis does not occur at such a steady rate Greatly affected by intensity of light, temperature, and CO 2 levels Can be measured directly via CO 2 intake and O 2 production amounts IF adjusted to account for respiration Biomass (amount of plant/size) is an indirect method of measuring rate of photosynthesis— indirect b/c a lot of other potential factors

Photosynthesis-rates 0 Day 1Night 1Day 2Night 2 O 2 released + Photosynthesis Respiration O 2 taken in --

Photosynthesis-rates Light intensity—varies inversely with the square of the distance (farther away, less intense) Rate of photosynthesis intensity Enzymes at max rate

Photosynthesis-rates Temperature Rate of photosynthesis Temp Enzymes and other proteins begin to get denatured

Photosynthesis-rates CO 2 concentration Rate of photosynthesis CO 2 Plateaus unless light intensity or temp. go up