PHOTOSYNTHESIS BIOLOGY RIVERDELL HIGH SCHOOL Dr. Brandoni

SO FAR…. Themes that keep arising: Structure/function: - proteins, -enzymes, cell membrane fluid- mosaic model, phospholipid chemistry and polarity… Maintaining balance and characteristics of life: -protein shape and temp/acidity, enzyme specificity and homeostasis, osmosis- water regulation, transport… Conservation: of mass, of energy

MOST RECENTLY: Structure/function of cell membrane and its role in transport in order to maintain homeostasis. MOST RECENTLY: Structure/function of cell membrane and its role in transport in order to maintain homeostasis. Which required energy? Which required energy? In pairs: Where do our cells get energy from? In pairs: Where do our cells get energy from? What is the energy carrying molecule? What is the energy carrying molecule? Where is the energy held in its structure? Where is the energy held in its structure? What do we need to do to get energy? What are “we” called? What do we need to do to get energy? What are “we” called? Where does our energy ultimately come from? Where does our energy ultimately come from? PLANTS- PHOTOSYNTHESIS

WHERE IS THE KITCHEN OF THE PLANT? CHLOROPLASTS CHLOROPLASTS IN THIS UNIT WE ARE GOING TO LOOK AT THE STRUCTURE/FUNCTION of CHLOROPLASTS IN GENERATING ENERGY AND EXAMINE HOW LIGHT IS CONVERTED TO CHEMICAL ENERGY IN THIS UNIT WE ARE GOING TO LOOK AT THE STRUCTURE/FUNCTION of CHLOROPLASTS IN GENERATING ENERGY AND EXAMINE HOW LIGHT IS CONVERTED TO CHEMICAL ENERGY

MAIN QUESTIONS: Photosynthesis A. What is photosynthesis? A. What is photosynthesis? B. Where does it take place? B. Where does it take place? C. When does it take place? C. When does it take place? D. What happens during photosynthesis? D. What happens during photosynthesis?

LAW OF CONSERVATION OF ENERGY: Carbon Cycle LAW OF CONSERVATION OF ENERGY: Carbon Cycle DO NOW: 1. What does the Law of conservation of energy state? 2. What three things do plants need to stay alive? What do they make from the raw materials? 3. What are the equations for photosynthesis and respiration? 4. THINK: Do plant cells undergo cell respiration?

What colored light is MOST useful in photosynthesis? Least? What colored light is MOST useful in photosynthesis? Least?

What colored light is MOST USEFUL? Which is LEAST? MOST USEFUL…. RED and BLUE LEAST USEFUL GREEN!!! HOW CAN THIS BE?????

III. Light and Photosynthesis A. Nature of Light 1. light is electromagnetic radiation a.travels in a vacuum at 186,000miles/sec a.travels in a vacuum at 186,000miles/sec b. other examples include microwaves, b. other examples include microwaves, radio waves, X-rays, gamma rays radio waves, X-rays, gamma rays c. each type has a different wavelength c. each type has a different wavelength and frequency and frequency

Nature of Light 2. white light is made of different colors Red Orange Yellow Green Blue Indigo Violet Decreasing wavelength > Decreasing wavelength > Increasing frequency and energy > Increasing frequency and energy > 3. light that hits an object can be absorbed, transmitted or reflected transmitted or reflected 4. color of light reflected is color you see a. all colors reflected - color is white a. all colors reflected - color is white b. all colors absorbed - color is black b. all colors absorbed - color is black all but blue absorbed - color is blue c. all but blue absorbed - color is blue

The Visible Spectrum

WHAT DOES LIGHT PROVIDE? Light in photosynthesis Light in photosynthesis provides energy that will be stored provides energy that will be stored in the bonds of a carbon compound in the bonds of a carbon compound

Bottom Line: Photosynthesis can be divided into 2 phases: LIGHT REACTIONS: (NEED LIGHT) LIGHT REACTIONS: (NEED LIGHT) Light is converted into chemical energy Light is converted into chemical energy H 2 0 breaks to H2 + O (release O 2 ) H 2 0 breaks to H2 + O (release O 2 ) H 2 0 is USED H 2 0 is USED O 2 are MADE and ENERGY (ATP) !!!! O 2 are MADE and ENERGY (ATP) !!!! CALVIN CYCLE (Dark Reactions): CALVIN CYCLE (Dark Reactions): CO 2, is USED (and energy used) CO 2, is USED (and energy used) C 6 H 12 O 6 is MADE C 6 H 12 O 6 is MADEPHOTOSYNTHESIS 6CO 2 + 6H C 6 H 12 O 6 + 6O 2 6CO 2 + 6H C 6 H 12 O 6 + 6O 2

DO AS WE GO QUESTIONS 1. What are the 2 phases of photosynthesis? 2. Where do they occur? ….to answer this, we need to look at the choloroplasts in detail…

Structure of the Chloroplast

WHERE DO THE LIGHT PHASE AND CALVIN CYCLE TAKE PLACE? LIGHT: Thylakoid LIGHT: Thylakoid CALVIN CYCLE: Stroma CALVIN CYCLE: Stroma

The Chloroplast

The Chloroplast and Pigments 1. Structure a. grana: stacks of a. grana: stacks of thylakoid membranes thylakoid membranesPIGMENTS: 1) chlorophyll a: absorbs light in the 1) chlorophyll a: absorbs light in the red range and some in the blue range red range and some in the blue range 2) chlorophyll b: absorbs more in the 2) chlorophyll b: absorbs more in the blue range and assists chlorophyll a blue range and assists chlorophyll a

DO…as we go Questions How does light transfer its energy? a. Pigments in chloroplast absorb light a. Pigments in chloroplast absorb light 1) light excites electrons 1) light excites electrons Excited electrons transfer energy to high energy compounds

IV. Light Phase - Photosynthesis A. Chloroplast and Pigments 3) accessory pigments (carotenoids) 3) accessory pigments (carotenoids) -yellow, orange, brown pigments that -yellow, orange, brown pigments that absorb in the green range and absorb in the green range and sometimes the blue range and pass sometimes the blue range and pass energy to chlorophyll a energy to chlorophyll a THINK: Where do autumn leaves get their colors?

Light Absorption by Pigments in the Chloroplast

Light Waves Absorbed and Reflected by the Leaf

Light Phase of Photosynthesis

VI. Alternate Pathways C. CAM Pathway C. CAM Pathway 1. Carbon dioxide is fixed in a variety 1. Carbon dioxide is fixed in a variety of compounds of compounds 2. open stomata at night and close 2. open stomata at night and close them during the day to conserve them during the day to conserve water water 3. these plants grow slowly 3. these plants grow slowly 4. examples are cactus and pineapple 4. examples are cactus and pineapple

Cross Section of a Leaf

Stomata Several Stomata Open Closed Showing Guard Cells Stomata Several Stomata Open Closed Showing Guard Cells

Light and Dark Phase Compared

VII. Rate of Photosynthesis A. Depends on 1. light intensity - increases as light intensity increases, then levels off intensity increases, then levels off 2. temperature – increases, reaches a high point, then decreases as temperature increases 3. carbon dioxide levels – increases as CO 2 levels increase, then levels off CO 2 levels increase, then levels off

Light Intensity and Rate of Photosynthesis

Temperature and Rate of Photosynthesis

CO 2 Concentration and Rate of Photosynthesis

Three Factors Affecting Rate of Photosynthesis Light Intensity CO 2 Concentration Temperature Three Factors Affecting Rate of Photosynthesis Light Intensity CO 2 Concentration Temperature