March 14, 2011 Agenda: Photosynthesis Lesson Photosynthesis Worksheet Review: Respiration Exam Lab Activity 24

Do Now: Pass forward light-reaction drawings 2) Describe what happens when chlorophyll absorbs light energy Electrons become excited, and are passed down the electron transport chain on the thylakoid membrane Energy is absorbed by the electron, exciting it. Electron will be passed down the ETC and enzymes in membranes of the chloroplasts will release energy used to make ATP

If there is no CO2, very little oxygen was produced Experimental set up Test tube #1: Test Tube #2: (Experimental) (Control) Light Light Chloroplasts Chloroplasts H2O H2O No CO2 CO2 If there is no CO2, very little oxygen was produced How could we test our solution to ensure that there is no carbon dioxide present? Set up experiment two times,s once with no carbon dioxide and no oxygen If there is no carbon dioxide, very little oxygen is released. What is our problem?

AIM: Why is carbon dioxide necessary for photosynthesis? Why do we need carbon dioxide to make oxygen during photosynthesis?

Review: Photosynthesis CO2 + H2O (light energy)  C6H12O6 + O2

H2O  2 H2 + O2 This reaction is very endergonic Hydrolysis: splitting of water Water is being OXIDIZED Splitting of water. This can be achieved using a Hoffman’s apparatus Water is losing its hydrogen http://www.youtube.com/watch?v=OTEX38bQ-2w

If water is being oxidized, what else must happen? Hydrogen acceptors

Water is oxidized, NADP is reduced

On a sunny day, the light dependent reactions will occur rapidly On a sunny day, the light dependent reactions will occur rapidly. NADP will be reduced to NADPH. There is a limited amount of NADP in the thylakoid of the plant. …What’s the problem?

NADPH needs to be recycled to NADP for photosynthesis to continue to occur. NADPH will lose its hydrogen; CO2 will act as a hydrogen acceptor

Dark Reactions, Light-Independent Reactions, Calvin Cycle: NADPH and CO2 will be used to make glucose.

Light Reactions: Summary

Do Now: Take out homework

Dark Reactions Synthesis of glucose from NADPH2 and CO2 using ATP energy Takes place in the stroma of the cell

Dark Reactions Calvin was interested in studying the process Of the “Dark Reactions”

Calvin traced carbon using a radioactive isotope (C14) Chlorella- algae

Do Now: Why are the following necessary for photosynthesis? Water: donates H+’s to form a hydrogen gradient and electrons through the ETC CO2: combines with hydrogen from NADP to produce glucose Light- excites electrons to pass through ETC Water donates hydrogens to build to a hydrogen gradient Donates electrons to the electron transport chain Light- provides the energy to excite electons in photosystem II CO2- accepts hydrogens from NADPH to recycle it to NADP

Review Calvin’s Experiment Whoops! Not THAT Calvin….

Calvin’s Problem: How can carbon dioxide form glucose during photosynthesis?

Calvin’s Experiment 1) Calvin exposes the Chlorella (algae) to radioactive C 14 in C 14 O2 2) Allows photosynthesis to occur in lollipop apparatus 3) “Freezes” the reaction using ethanol alcohol a) release chlorophyll b) denature the enzymes involved in photosynthesis 4) Separates out radioactive carbon using CHROMATOGRAPHY

Chromatography- technique of separating different pigments based on chemical properties

5. Observes radioactive compounds using “radioautography” Technique that allows radioactive carbon to become visible. By freezing photosynthesis at different times, Calvin was able to trace how carbon dioxide was converted to sugar. This is is Calvin’s experimental procedure to determine the steps by which CO2 is converted into glucose. Now that we know how he set up his experiment, what question can we ask? Elicit AIM:

AIM: What did Calvin discover?

Results of Calvin’s Experiment ON BOARD: have students interpret the results of the experiment. Begin with carbon dioxide, what’s our first compound to appear? (3 carbon PGA). What’s our second compound to appear? 3 carbon with 2 phosphates attached Where might those phosphates have come from? ATP Then we have a 3 carbon sugar (PGAL)- we’ve seen this sugar before during a different process. Cellular respiration (show cellular respiration slide 5 carbon sugar ribulose bisphosphate And then a 6-carbon sugar- glucose Calvin had hypothesized that CO2s combine to make glucose If a CO2 combines with another CO2, then how many carbons would we have? TWO Do we see a two carbon compound in his results? No So there must be a different pathway from Carbon Dioxide to glucose. Let’s take a look at what happens.

Glycolysis

Calvin Cycle: A STEP A: Six carbon dioxide molecules enter the cycle from the atmosphere. The carbon dioxide molecules combine with six 5-carbon molecules. They rearrange to form 3 carbon molecules. Look at our results, what is the first molecule to appear afte CO2? PGA How many carbons? 3 SO we form a 3 carbon compound

Step B: Energy investment stage The 12 3 carbon molecules are then converted into higher energy forms. The energy for this conversion comes from ATP and NADPH Where does the ATP and NADPH come from? Where does the ATP and NADPH come from? Light-dependnet reactions

STEP C: Two of the twelve 3-carbon molecules rearrange into two similar 3 carbon molecules (PGAL) How many carbons are left? 30 How many 3 carbon molecules? 10 6 More ATP are used to make ribulose. Why do we need to make ribulose? So the cycle can continue again

Sheesh! That’s a lot of biochem.. Let’s summarize: How many CO2 are needed to synthesize 1 glucose? How many ATP are needed to synthesize 1 glucose? How many NADPH are needed to synthesize 1 glucose?

Calvin Cycle Energy input Plants use energy that ATP and NADPH

Do Now: Take out homework Calvin Cycle Review How many: CO2 = 6 ATP= 18 ATP NADPH= 12 NADPH http://www.youtube.com/watch?v=_NIhg1qa_L0

AIM: Why did the plant die? I was so excited that I got this new plant. Look at my plant. AIM: Why did Ms. Simon’s plant die?

Hypothesis: If the plant dies, then Photosynthesis is not occurring

Materials: Benedict’s Solution and Lugol’s Solution Indicators for glucose and starch Work together: What could I do?

Factors that may affect photosynthesis: Sunlight Water CO2 Nutrients in the soil Temperature Light Temperature CO2 Water

Plants can still produce glucose for a short time in the dark…. Why? However, Plants need NADPH and ATP from the Light- Dependent reactions to continue photosynthesis Plants can still undergo the Calvin Cycle or light dependent reaction

Rainforest Desert Large, broad leaves Small, needlike leaves Cuticle covering

How can temperature affect photosynthesis? Enzymes in Photosynthesis work best between 0 and 35 degrees Celsius, after 35 Celsius, enzymes denature

How will carbon dioxide affect photosynthesis? Carbon Dioxide is necessary during the Calvin Cycle to produce glucose

How will water affect photosynthesis?

How will water be transported to the top of trees?

Root Pressure Concentration of nutrients and sugar is higher inside the roots than outside the plant… Water will move via Osmosis into the roots

Cohesion-Adhesion Cohesion: water Molecules attract to One another Adhesion: water Attracts to other sub- Stances Cohesion and Adhesion lead to capillary action- tendency for water to rise in a thin tube

Transpirational Pull- water moves into the leaves via osmosis loss of water through the leaves Root pressure, capillary action, and transpirational pull contribute to the movement of water within a plant

Wilting Too little water decreases TURGOR pressure in a plant, causing it to wilt

Summary: What may be wrong with Ms. Simon’s plant?