Using Light to Make Food PHOTOSYNTHESIS Using Light to Make Food

It provides food for virtually all organisms Photosynthesis is the most important chemical process on earth because: It provides food for virtually all organisms SWEET!!!!

BIG PICTURE: Photosynthesis Light energy is used to make sugar and other food molecules from carbon dioxide and water

6 H2O + 6 CO2 ----------> C6H12O6+ 6 O2 Chemical Reaction sunlight 6 H2O + 6 CO2 ----------> C6H12O6+ 6 O2 How does this equation compare to the cell respiration one? Photosynthesis: An Overview of Photosynthesis (click)

Autotrophs“Self-feeders” Make their own food Also referred to as: Producers = produce the biosphere’s food supply

Photosynthetic Plants Forests (land) Kelp (ocean) Diatoms (microscopic)

Leaf Structure

1. Stoma (sing.) in leaf lower epidermis Is the opening carbon dioxide, oxygen. And water in/out Stomata (pl.)

Leaf CS 2. Upper Epidermis 4. Mesophyll-cells containing chloroplasts 3. Lower epidermis Covers and protects see stoma –in lower epidermis only

4. Mesophyll = Palisade Layer + Spongy Layer

Waxy, waterproof coating (to retain H2O) 5. Cuticle Waxy, waterproof coating (to retain H2O)

6. Palisade Layer cylindrical cells, vertically oriented, closely packed

O2 ,CO2, H20 vapor go in/out 7. Spongy Layer cells are irregular in shape and loosely packed O2 ,CO2, H20 vapor go in/out

8. Guard Cells Control Stomata Full guard cells (turgid) opens the stoma. Flaccid (lost water) guard cells, the stoma closes. ANIMATION: Stoma What causes them to open? What goes into the stomata?

9. Plant Vein: Xylem + Phloem Xylem-(blue) carries water Phloem (thicker cell wall)-(yellow) carries food

10: Air Space Gas Flow Through Leaf

Guard Cells Animations LabBench (guard cell animation) Another animation of opening and closing of guard cells http://academic.kellogg.cc.mi.us/herbrandsonc/bio111/animations/0021.swf (really nice)

Water Movement LINK: http://www.sciencemag.org/sciext/vis2005/show/transpiration.swf

Draw the Elodea Cell 400X

Leaf CS (cross section)

Photosynthesis in Elodea Lab See oxygen bubbles coming from the Elodea What conditions are best?

Elodea Bubbles Movie sLowlife Exhibit

7.2

Chloroplast

Chloroplast Diagram Stroma = thick fluid between the thylakoids thylakoids = disks within the chloroplasts granum=stack of thylakoids (grana pl.)

What is the difference between grana and granum?

STROMA So what’s the difference between the stoma and the stroma? STOMA = opening in lower epidermis STROMA = area around thylakoid disks in the chloroplast

Chloroplast Diagram Inner Membrane Thylakoid space Intermembrane Space Stromal lamella = connect grana D. Outer Membrane Thylakoid membrane Inner Membrane Thylakoid space Intermembrane Space

Chloroplasts TEM Note the stacks of thylakoid disks = grana Note area between = stroma

THYLAKOIDS

Photosynthesis

Summary IN

Summary OUT

Nice Little Photosynthesis Movies VCAC: Cellular Processes: Photosynthesis: The Movie VCAC: Cellular Processes: Photosystem II: The Movie

7.5 Overview of Photosynthesis

What happens here? Assembles sugar molecules using CO2 Light Dependent Reaction (LDR) Converts light energy to chemical energy + O2 Light Independent Reaction (LIR) Assembles sugar molecules using CO2

Where does energy come from? Light Dependent Reaction LDR Uses light energy Light Independent Reaction LIR (Calvin Cycle) uses ATP and NADPH (from LDR)

PSI and PSII PSI and PSII animation Another PSI and PSII animation

Where is it located in the cell? LDR occurs in thylakoid membranes of chloroplast’s grana LIR (aka Calvin cycle) occurs in stroma of chloroplast

Final Products of Each? LDR ATP and NADPH Also O2 LIR sugar

Carbon fixation = FIXATION = make in a usable form NEW VOCAB. WORD Carbon fixation = incorporation of carbon into an organic molecule (useable) EXAMPLE: CO2 into C6H12O6 FIXATION = make in a usable form

LIGHT CHLOROPHYLL

Pigments in Plants Pigments are light-absorbing molecules Different pigments absorb or reflect different colors

Wavelength Chlorophyll a wavelengths absorbed: blue-violet and red Reflects: grass green Wavelength

An accessory chlorophyll in plants Chlorophyll b Absorbs: blue and orange Reflects: yellow-green An accessory chlorophyll in plants

Other pigments in plants Carotenoids-orange Absorb: blue-green Reflect: yellow-orange

FYI Why do leaves change color? Chlorophyll breaks down and exposes the other colors that were there all along, but were masked by the green chlorophyll. As fall comes there are shorter days of sunlight Less photosynthesis means less food for plants.

“Absorption of Chlorophyll” DO WORKSHEET “Absorption of Chlorophyll” Photosynthesis: The Action Spectrum for Photosynthesis (experiment link)

Chlorophyll a and Chlorophyll b

7.7 Electromagnetic Photosynthesis: Electromagnetic Energy (move the arrow)

#1 What are… PHOTONS Fixed quantity (packet) of energy

Distance between crests of two waves Λ = symbol for wavelength

Light travels as waves and as photons “Wave-particle theory”

PHOTONS Smallest unit of light emitted when an electron jumps to a more excited state named by Einstein light

Shorter the wavelength... The greater the energy

#2 When an e- in a pigment absorbs a photon... Electron goes from “ground state” to “excited state”

Energy from the sun ANIMATION: Atomic absorption diagram (how energy causes an electron to jump levels)

#3 Excited State is Very Unstable As e- falls back to the ground state it might: lose energy as heat emit light gives off a photon IN A CHLOROPHYLL MOLECULE IT WILL …

PHOTOSYSTEM

Now for photosynthesis

#3 + #4 Chlorophyll passes its photon to: A neighboring molecule called the primary electron acceptor

Reaction Center of Chlorophyll Chlorophyll a is the only one that donates to the primary acceptor CENTER

Pigments in a Photosystem (Light RXN) reaction center Figure 7.11 Page 122

“Light capturing Antenna” Transfer light energy to the reaction center

#4 “Photosystem” = PS Antenna molecules + reaction center + primary electron acceptor

Cyclic Electron Flow (Light RXN) electron acceptor Electron flow through transfer chain sets up conditions for ATP formation at other membrane sites. electron transfer chain e– e– ATP e– Figure 7.12 Page 122

#5 TWO photosystems: PS I and PS II: absorbs λ (λ = wavelength) PS I -P 700 nm PS II -P 680 nm

Animations P700 and P680 Animation Making ATP and NADPH (Light Dependent Reaction)

7.8 In light reaction: ETC generates ATP, NADPH, O2 1. Light energy is absorbed 2. Electrons excited 3. Energy from ETC used to make ATP and NADPH

WATER

#2 PS II: Breaking up water The P680 requires an electron, which is taken from a water molecule, breaking the water into H+ ions and O-2 ions. These form the O2 that is released. 2 H2O 02 + 4e- + 4H+

What process drives each? NADPH forming ATP forming O2 formation Redox and ETC Chemiosmosis

NOTE: Final Electron Acceptor is NADPH Not Oxygen (Oxygen is given off) in Light Reaction of Photosynthesis

Animation Making Oxygen (You’ll love the noises) (I hate ‘em)

Chemiosmosis Again #1 Remember chemiosmosis in cellular respiration, well, here it is again.

7.9 Question #2 PS I: Forming H+ ions to form ATP By chemiosmosis

7.9 #3 There would now be more H+ ions located: Came from the stroma and went to the thylakoid interior

7.9 #4 The H+ ions move through what port to move back into the stroma? ATP synthase

#5 Photophosphorylation is the process of converting energy from a light-excited electron into the phosphate bond of an ADP molecule into ATP. This occurs when the electrons from water are excited by the light in the presence of P680.

CALVIN CYCLE Or the LIR

Can the Calvin Cycle also be called the “dark reaction?” PEANUT: It does not need light to run, but it can also run during light. So…the “dark cycle” term is not used anymore.

Animation Noncyclic photophosphorylation (THIS ONE IS MY FAVORITE) Cyclic and Noncyclic Photophosphorylation (first one is very detailed, second one is better for HS) Photosynthetic ETC and ATP Synthesis

View Me Photosynthetic Electron Transport and ATP Synthesis

7.10 #1 Calvin Cycle Uses the CO2 (from the atmosphere) and ATP and NADPH (from light reactions) to run the sugar factory

Step 1: Carbon Fixation RUBISCO ENZYME combines 3 molecules of CO2 with ribulose bisphosphate (5-C) RuBP makes 6-C

#2 G3P “Glyceraldehyde- 3 phosphate” the energy-rich molecule made in the Calvin cycle it can be used to make glucose or other organic molecules

The enzyme rubisco combines with CO2 to form 3-C molecule, 3PGA #3 The enzyme rubisco combines with CO2 to form 3-C molecule, 3PGA

It takes 6 turns to make one glucose molecle #4 It takes 6 turns to make one glucose molecle

Regeneration of RuBP Energy from ATP is used to reform RuBP molecules (hey, its recyclable!)

Occurs in stroma of chloroplasts Calvin Cycle Occurs in stroma of chloroplasts

7.11 Review of Photosynthesis

Summary: Calvin Cycle

Overall Equation

QUIZ TIME: structures The light reactions (LDR) of photosynthesis occur in the __________, and the Calvin cycle (LIR) occus in the __________ of the chloroplast.

ANSWER The light reaction occurs in the thylakoid membranes and the dark reaction occurs in the stroma.

Which equation summarizes photosynthesis? A. water + starch ---> glucose + glucose + glucose B. water + carbon dioxide ---> oxygen + glucose + water C. glucose + oxygen ---> water + carbon dioxide + ATP D. glucose + glucose ---> maltose + water

B. water + carbon dioxide ---> oxygen + glucose + water ANSWER B. water + carbon dioxide ---> oxygen + glucose + water

In what organelle does photosynthesis occur? A. the nucleus B. chloroplasts C. the vacuole D. the cell wall

ANSWER B. Chloroplast

QUESTION: Four identical plants are grown under different colored light bulbs. Under which color will the release of oxygen gas be slowest? A. Green B. blue C. orange D. red

ANSWER: A. Green

QUIZ TIME The reason why ADP + P form ATP in thylakoid membranes is… A movement of electrons between photosystem II and photosystem I. B oxidation of water C oxidation of NADPH D absorption of photons by chloroplast pigments E higher concentration of H+ inside versus outside the thylakoid membranes

ANSWER E. a higher concentration of H+ ions inside vs. outside the thylakoid membranes

QUIZ TIME Water is broken down and the electrons from water pass through photosystem II and photosystem I before adding e- to: A carbon dioxide B NADP+ C plastoquinones D FAD E rubisco

ANSWER NADP+ to make higher energy NADPH

QUIZ TIME Which of the following would have the smallest effect on the rate of photosynthesis in a green plant? A. carbon dioxide concentration B. light intensity C. oxygen concentration D. water available

C. oxygen concentration ANSWER: C. oxygen concentration

QUIZ TIME A. more concentrated with ATP During photosynthetic electron transport, the interior compartment of the thylakoid membranes becomes: A. more concentrated with ATP B. more concentrated with H+ ions C. less concentrated with H+ ions

HINT: Distribution of H+ ions Light Rx more inside Dark Rx Even in and out

More concentrated with H+ ions ANSWER More concentrated with H+ ions

QUIZ TIME Which of the following is produced during photosynthesis? A. carbon dioxide B. lactic acid C. DNA D. PGAL  

ANSWER D. PGAL

QUIZ TIME Atmospheric oxygen that is inhaled by animals comes from: A. carbon dioxide molecules split during the light reactions B. carbon dioxide split during the dark reactions C. water molecules split during the light reactions D. water molecules split during the dark reactions

C. water molecules split during the light reactions ANSWER C. water molecules split during the light reactions

QUIZ TIME What change occurs during photosynthesis? A. solar energy is converted to chemical energy B. kinetic energy is converted to chemical energy C. chemical energy is converted to radiant energy D. water is converted to chemical energy

A. solar energy is converted to chemical energy ANSWER A. solar energy is converted to chemical energy

Cuticle Epidermis Guard cells Palisade Phloem Xylem Spongy Mesophyll Stomata Bundle Sheath

A=cuticle B=Upper epidermis C=Vein D=Phloem E=xylem F=Palisade layer G=spongy layer H=guard cell I=stomata

QUIZ TIME The overall source of energy for photosynthesis is: A. energy from the sun B. energy from ATP C. energy when oxygen is produced

ANSWER A. energy from the sun

QUIZ TIME What three events occur during the light reactions of photosynthesis? Forming ATP NADP+ to NADPH Fixing CO2 Releasing O2

ANSWER Forming ATP NADP+ to NADPH Releasing O2

QUIZ TIME Which of the following does not happen in photosystem I? ATP is produced electron transport in the thylakoid membranes light energy is used NADPH is formed

HINT

ANSWER (which is NOT) NADPH is formed

QUIZ TIME Where does the Calvin Cycle take place? Thylakoid membranes of chloroplasts Stroma of chloroplasts Matrix of mitochondria Inner membrane of mitochondria

Stroma of chloroplasts ANSWER Stroma of chloroplasts

What is the name of the enzyme that causes CO2 to form glucose? QUIZ TIME What is the name of the enzyme that causes CO2 to form glucose? ATPase glucosease rubisco

ANSWER rubisco

QUIZ TIME What two high energy compounds are required for this reaction? ATP NADH NADPH ADP FADH

ANSWER ATP and NADPH

QUIZ TIME What is the name of the process in which carbon dioxide is made into glucose? Krebs cycle Calvin cycle Einstein cycle

ANSWER CALVIN CYCLE (or sometimes the Calvin-Bensen Cycle)

QUIZ TIME Which does NOT happen in the Dark Reaction: using ATP using NADPH using Carbon Dioxide making water

ANSWER MAKING WATER

QUIZ TIME What are the products of the dark reaction? ATP ADP glucose NADP+

ANSWER ADP NADP+ glucose

QUIZ TIME The reason why ADP + P form ATP in thylakoid membranes is… A movement of electrons between photosystem II and photosystem I. B oxidation of water C oxidation of NADPH D absorption of photons by chloroplast pigments E higher concentration of H+ inside versus outside the thylakoid membranes

ANSWER a higher concentration of H+ ions inside vs. outside the thylakoid membranes

QUIZ TIME During photosynthetic electron transport, the interior compartment of the thylakoid membranes becomes: A. more concentrated with ATP B. more concentrated with H+ ions C. less concentrated with H+ ions

ANSWER More concentrated with H+ ions

QUIZ TIME The overall source of energy for photosynthesis is: A. energy from the sun B. energy from ATP C. energy when oxygen is produced

ANSWER A. energy from the sun

QUIZ TIME What three events occur during the light reactions of photosynthesis? Forming ATP NADP+ to NADPH Fixing CO2 Releasing O2

ANSWER Forming ATP NADP+ to NADPH Releasing O2

QUIZ TIME What is the name of the process in which carbon dioxide is made into glucose? Krebs cycle Calvin cycle Einstein cycle

ANSWER CALVIN CYCLE (or sometimes the Calvin-Bensen Cycle)