Photosynthesis. Plant Anatomy. Plant Anatomy. Plant Anatomy 1/14/2015. Stems. Leaves

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1 //205 Plant Anatomy Photosynthesis Roots Anchor plant to the ground Absorb water minerals from soil (by osmosis) Store food for plant (glucose made in photosynthesis is stored as starch) Plant Anatomy Stems Transport water from the roots to leaves (xylem) Transport food (glucose) made in leaves down to roots for storage (phloem) Plant Anatomy Leaves Photosynthesis, accomplished by the cooperation of many different cell types. Upper epidermis Spongy mesophyll cell Guard cell (opening) Stoma Phloem cells (glucose down) Photosynthesis = Process of converting sun energy into glucose energy 6 CO E > C O 2 Gas diffuses into leaf through stomata Reactants Travels from roots to leaves via xylem () E captured by chlorophyll (inside chloroplast) Products Life s primary food molecule Gas diffuses out into air (byproduct)

2 Low E Longer wavelength //205 Organelle that contains chlorophyll undergoes photosynthesis Reactants: 6 CO 2 2 Products: C O 2 Palisade Cells Thylakoid Grana Leaf Organ Thylakoid membrane contains chlorophyll Stroma H atom ion p O n p O n Information about Light: The Visible Spectrum Red Orange Yellow Green Blue Indigo Violet High E Shorter wavelength ion resevoir Phospholipid bilayer One Why are leaves green? Why is the sky blue? Green is green because it reflects green absorbs the energy of all other colors Absorbed stored energy in carbohydrates produced by photosynthesis Reflected color you see (doesn t give plant energy) 2

3 Absorption of by chloroplast pigments //205 Light Reflected Pigment Molecule that absorbs energy from the sun; give leaves their color Absorbed Granum Transmitted a b Carotenoids Wavelength of (nm) In plants, chlorophyll a b are the main pigments. Found in chloroplasts Pigments absorbs energy from visible spectrum, mostly violet/blue & orange/ red (reflects green) Absorption spectra White Refracting prism solution Photoelectric tube White Refracting prism solution Photoelectric tube Galvanometer Slit moves to pass of selected wavelength Green The high transmittance (low absorption) reading indicates that chlorophyll absorbs very little green. Slit moves to pass of selected wavelength Blue The low transmittance (high absorption) reading indicates that chlorophyll absorbs most blue.

4 Absorption of by chloroplast pigments //205 CH CHO in chlorophyll a in chlorophyll b Porphyrin ring: -absorbing head of molecule; note magnesium atom at center Hydrocarbon tail: interacts with hydrophobic regions of proteins inside thylakoid membranes of chloroplasts; H atoms not shown Accessory Pigments Absorb that chlorophyll can t Allow plants to use more energy from than could be trapped by chlorophyll alone Examples: Carotenoids (appears orange, yellow, red because it reflects these colors) Xanthophyll I II (appears yellow because it reflects this colors) **Remember** More absorbed = more energy for photosynthesis a b Carotenoids Adenosine Triphosphate Wavelength of (nm) Absorption spectra Function: Carries energy from the mitochondria to all other cell organelles (to the nucleus, plasma membrane, etc.) Structure - Adenine, Ribose, Phosphate (P) Adenosine (A)

5 Stroma Thylakoid membrane Stroma ion channel ion channel //205 A-P-P-P High energy bonds (only occur between phosphate bonds) A-P-P-P ADP (Adenosine diphosphate) AMP (Adenosine monophosphate A-P-P A-P E from bonds of glucose A-P-P ADP + P E for all cell work Photosynthesis Stage : Light Phase ion Reservoir molecules ion Reservoir Occur at same time Photosystem II Photosystem I 5

6 ion channel ion channel //205. Light hits chlorophyll excites an electron so that it jumps out of the chlorophyll molecule. This happens in both Photosystems II I. Excited state Heat Photon molecule Photon (fluorescence) Ground state Excitation of isolated chlorophyll molecule Fluorescence 2. This excited electron moves down an electron transport chain, releasing Energy. ion Reservoir. A chlorophyll molecule is now missing an electron. It gets this electron replaced from a water molecule. The water molecule gets is split by an enzyme as follows: (waste gas, diffuses out of leaf through stomata) enzyme 2 ions for the ion Reservoir 2 for replacing lost in chlorophyll 2 ion Reservoir 6

7 ion channel ion channel ion channel // The Energy released from the ETC is used to actively transport (pump) ions against their concentration gradient from the stroma (outside the thylakoid) into the ion reservoir (inside the thylakoid). 2 ion Reservoir 5. ions collect in the Hydrogen Ion Reservoir. Their concentration builds they repel each other due to like charges. E Released from e- passing (pumps H+) 2 ion Reservoir E Released from e- passing (pumps H+) 6. ions rush back into the stroma (from high to low concentration) through the Synthase enzyme, which uses this energy (rushing) to join ADP P (make ). 2 ion Reservoir (H+ collecting repelling) 5 7

8 ion channel ion channel //205 E Released from e- passing (pumps H+) ADP + P 7. ions join with the electrons coming off the ETC form Hydrogen atoms. Hydrogen atoms get picked up by NADP NADP NADPH ion Reservoir (H+ collecting repelling) E Released from e- passing (pumps H+) 7 NADPH NADP + 2 ADP + P Go to stage 2 2 NADPH 2 6 Mill makes ion Reservoir (H+ collecting repelling) 5 Photosystem II Photosystem I Light Phase Summary Only happens if hits chlorophyll Requires, which gets split Produces: NADPH 2 Go to stage 2 Gas Released into the air Photosynthesis Stage 2 Calvin Cycle 8

9 //205 Location: Stroma of chloroplast Requires: E from H from NADPH 2 CO 2 from the stomata Main Idea: CO 2 combines with H (carried by NADP) to form glucose Produces: Glucose Releases NADP ADP/P recycled to phase * 6 CO 2 * 6 molecules (6-C) Splits in /2 RuDP 5-carbon molecule (RuBP) 6 ADP + P E *6 From the phase 2 PGAL (-C) phophoglyceraldehyde 2H E 2 PGA (-C) phophoglycerate * 2 * From the phase 2 ADP + P *2 NADPH 2 * From the phase 2 NADP 6 CO NADPH C NADP + + From the reaction 8 ADP + 8 P + 6H 2 0 *Need 6 CO 2 to make ONE glucose* glucose Used for cell respiration 2 PGAL molecules are used to make one glucose Light Phase Calvin Cycle CO 2 NADPH 2 ADP + P NADP Calvin Cycle O 2 C 6 6 9