PHOTOSYNTHESIS Chapter 8 Pages 201-214 THE LIGHT REACTION

What does the word mean? Photo - - - synthesis "with light - - - putting things together” Plants use glucose as food for energy and as a building block for growing. Sunlight energy is transformed to energy stored in the form of chemical bonds. This is a chemical reaction.

Plants are energy producers Like animals, plants need energy to live unlike animals, plants don’t need to eat food to make that energy Plants make both FOOD & ENERGY animals are consumers plants are producers Autotrophs make glucose and heterotrophs are consumers of it.

PHOTOSYNTHESIS Autotrophic Process: Plants and plant- like organisms make their energy (glucose) from sunlight. Stored as carbohydrate in their bodies. (a) Mosses, ferns, and flowering plants (b) Kelp (c) Euglena (d) Cyanobacteria

Why is Photosynthesis important? It allows plants to have energy to do work. Makes organic molecules (glucose) out of inorganic materials (carbon dioxide and water). It begins all food chains/webs. Thus all life is supported by this process. It also makes oxygen gas!!

Photosynthesis facts continued Plants gather sunlight with light – absorbing molecules called Chloroplasts. The main pigment is chlorophyll. Chlorophyll only absorbs light in certain parts of the visible spectrum.

What is the equation for the chemical reaction of photosynthesis? Six molecules of carbon dioxide react with six molecules of water to form 1 molecule of glucose and six molecules of oxygen.

WHY ARE PLANTS GREEN?

Different wavelengths of visible light are seen by the human eye as different colors. Gamma rays X-rays UV Infrared Micro- waves Radio waves Wavelength (nm) Visible light

The feathers of male cardinals are loaded with carotenoid pigments The feathers of male cardinals are loaded with carotenoid pigments. These pigments absorb some wavelengths of light and reflect others. Reflected light

Why are plants green? Reflected light Transmitted light

Plant Cells have Green Chloroplasts The thylakoid membrane of the chloroplast is impregnated with photosynthetic pigments (i.e., chlorophylls, carotenoids).

Light Reflected light Absorbed light Transmitted light Chloroplast

Chloroplast Pigments Chlorophyll a Chlorophyll b Carotenoids Chloroplasts contain several pigments Chlorophyll a Chlorophyll b Carotenoids Xanthophyll

Chlorophyll b Chlorophyll a Absorption of Light by Chlorophyll a and Chlorophyll b

Fall Colors In addition to the chlorophyll pigments, there are other pigments present. During the fall, the green chlorophyll pigments are greatly reduced revealing the other pigments. Carotenoids are pigments that are either red or yellow.

Chlorophyll a & b Chl a has a methyl group Chl b has a carbonyl group Porphyrin ring delocalized e- Phytol tail

Which color in the spectrum does chlorophyll a absorb the most? Violet Blue Green Yellow Orange Red

Which color in the spectrum does chlorophyll b absorb the most? Violet Blue Green Yellow Orange Red

Which color in the spectrum does chlorophyll a & b absorb the least? Violet Blue Green Yellow Orange Red

The History of Photosynthesis How do we know plants “make” there food?

Jan van Helmont’s Famous Tree Experiment

The year was 1642… “I took an earthen vessel, in which I put 200 pounds of earth that had dried in a furnace, which I moistened with rainwater, and I implanted therein the trunk or stem of a willow tree, weighing five pounds. And at length, five years being finished, the tree spring from thence did weigh 169 pounds and about three ounces. … Lest the dust that flew about should be mingled with the earth, I covered the lip or mouth of the vessel with an iron plate covered with tin and easily passable with many holes. … I again dried the earth up in the vessel, and there was found the same 200 pounds, wanting about two ounces.”

After Before 5 lb Willow 200 lb dirt Day 1 169 lb Willow 199 lb 14 oz dirt 5 years later 3400% Increase 0.00063% decrease in weight in weight

Questions? What question did van Helmont set out to answer? How would you explain how the tree gained 164 lbs or 75 Kg in mass? Jan van Helmont believed that the increase in mass was solely due to the water taken in by the plant. If van Helmont had tested his hypothesis correctly, the plants would not have grown. What is his misconception?

Jan van Helmont in short… Grew a willow tree Weighed soil before and after Added only Water Tree gained 164 lb or 75 Kg No change in mass of soil CONCLUSION (partially accurate)… Mass in plant comes from water. Van Helmont accounts for the “Hydrate” in carbohydrate.

John Priestly

Part 1 Priestly lit a candle. He then placed a glass jar over it… …and watched as the flame gradually died out.

Part 1 Priestly lit a candle. He then placed a glass jar over it… …and watched as the flame gradually died out.

Priestly reasoned that something in the air was necessary to keep the flame burning.

Part 2 Priestly then placed fresh mint leaves underneath the jar and allowed the entire setup to sit for a few days.

A few days passed…

Part 2 After a few days, Priestly found that he could relight the candle and it would burn for a while.

Part 2 After a few days, Priestly found that he could relight the candle and it would burn for a while.

Priestley concluded that the plant had produced the substance required for burning. What substance was consumed as the candle burned the first time? Oxygen

What must have been added to the jar to enable the candle to burn the second time? Oxygen

Where did this oxygen come from? The Plant

What do you think would happen if Priestly had put the plant and candle back in the jar for a few days then once again tried to light the candle? the plant would die the plant would light on fire the candle would light again the candle would not light again

What does this tell you about plants and oxygen? plants do not need all the oxygen they take in plants produce oxygen all the time plants produce as much oxygen as they need plants produce oxygen in the presence of light

The Other Experiment In another experiment, Priestly put a mouse under the jar and waited to see what would happen.

The Other Experiment In another experiment, Priestly put a mouse under the jar and waited to see what would happen. Sadly, the mouse eventually died.

The Other Experiment Later, Priestly put a mouse under the jar with fresh mint leaves and waited to see what would happen. To his surprise, both the mouse and plant survived for quite some time.

What important substance was produced by the plant? Oxygen

What important substance was produced by the mouse? Carbon Dioxide

Animals use Carbon dioxide Why were both the plant and the mouse able to survive under the jar? Plants use Oxygen Animals use Carbon dioxide

In Short…

Jan Ingenhousz

Jan Ingenhousz Out does Priestly Led to the discovery that plants need light to produce oxygen He performed Priestly’s experiment and discovered that the candle only remained

What’s going on in the Chloroplasts?

Plants Autotrophs: self-producers. Location: 1. Leaves a. stoma b. mesophyll cells – Plant tissue usually containing chlorophyll, that forms the interior parts of a leaf. Stoma Mesophyll Cell Chloroplast

Stomata (stoma) Pores in a plant’s cuticle through which water and gases are exchanged between the plant and the atmosphere. Oxygen (O2) Guard Cell Carbon Dioxide (CO2)

The major parts of a Mesophyll Cell Nucleus Cell Wall Chloroplast Central Vacuole

Chloroplast Organelle where photosynthesis takes place. Stroma Outer Membrane Thylakoid Granum Inner Membrane

Thylakoid Thylakoid Membrane Granum Thylakoid Space

PHOTOSYNTHESIS IN CHLOROPLASTS REVIEW CHLOROPLASTS CONTAIN: AN OUTER MEMBRANE HIGH PERMEABILITY AN INNER MEMBRANE NEARLY IMPERMEABLE THE STROMA AQUEOUS CONTAINS ENZYMES, DNA, RNA, RIBOSOMES THE “THYLAKOID” A MEMBRANEOUS COMPARTMENT DERIVED FROM INVAGINATIONS OF INNER MEMBRANE A SINGLE HIGHLY-FOLDED VESICLE “GRANA” : DISK-LIKE SACS GRANA ARE CONNECTED BY “STROMAL LAMELLAE”

How does Photosynthesis really work? But first… TWO OVERVIEWS OF PHOTOSYNTHESIS

reactions High-energy sugars Photosynthesis includes Calvin cycle Light-dependent reactions takes place in uses use take place in Thylakoid membranes Stroma NADPH ATP Energy from sunlight to produce to produce ATP NADPH O2 Chloroplasts High-energy sugars of

6CO2 + 6H2O + sunlight  C6H12O6 + 6O2

Redox Reaction The transfer of one or more electrons from one reactant to another. Two types: 1. Oxidation 2. Reduction

The loss of electrons from a substance. Or the gain of oxygen. Oxidation Reaction The loss of electrons from a substance. Or the gain of oxygen. Oxidation glucose 6CO2 + 6H2O  C6H12O6 + 6O2

The gain of electrons to a substance. Or the loss of oxygen. Reduction Reaction The gain of electrons to a substance. Or the loss of oxygen. Reduction glucose 6CO2 + 6H2O  C6H12O6 + 6O2

ENERGY AND WHAT IT LOOKS LIKE Adenosine Triphosphate

Comparison of ADP and ATP to a Battery Energy ATP Adenosine triphosphate (ATP) Adenosine diphosphate (ADP) + 1 Phosphate Energy Fully charged battery Partially charged battery See the energy in ATP is stored between the bonds of its phosphate groups.

There is too much energy stored in glucose, so its broken down slowly in order not to lose any energy. This energy is stored in ATP. When a -P group is added to ADP, it will have enough energy to react with other molecules. Also ATP is a nucleotide.

NADPH: Nicotinamide adenine dinucleotide phosphate Other Batteries NADPH: Nicotinamide adenine dinucleotide phosphate fully charged battery (high in energy) NADP+: Nicotinamide adenine dinucleotide phosphate weaker battery (low in energy)

Transfers energy very quickly Takes longer to get energy out ATP Glucose Short Term Long Term Storage Transfers energy very quickly Takes longer to get energy out Can’t store energy very long. (breaks down to ADP and loses energy) Can store energy very well. 1 molecule of glucose can hold 90 times more energy than ATP.

Chloroplasts: Sites of Photosynthesis Occurs in chloroplasts, organelles in certain plants All green plant parts have chloroplasts and carry out photosynthesis The leaves have the most chloroplasts The green color comes from chlorophyll in the chloroplasts The pigments absorb light energy

Steps of Photosynthesis (see diagram) Two main parts: 1. Light-dependent reaction (light cycle) 2. Light-independent reaction (Calvin Cycle)

AKA: light dependent reaction Light Cycle: AKA: light dependent reaction Where: takes place in the membrane of the thylakoid When: happens anytime a place has water and sunlight Why: it charges the batteries for use in the next cycle (ATP and NADPH) What it uses: H2O and sunlight and dead batteries (ADP and NADP+) What it makes: O2 and charged batteries (ATP and NADPH)

Two types of photosystems cooperate in the light reactions Photon ATP mill Photon Water-splitting photosystem NADPH-producing photosystem

LIGHT LIGHT Purple Goes in Red comes out Black is info INSIDE H+ e- Chlorophyll OUTSIDE

Calvin cycle: AKA: light- independent cycle, Dark cycle Where: Takes place in the stroma (liquid) of cholroplast When: Takes place anytime batteries are charged (day or night) Why: uses batteries to make sugar, which is stored for later use. What it uses: CO2 and charged batteries (ATP and NADPH) What it makes: Sugar (C6H12O6) and dead batteries (ADP and NADP+)

Purple Goes in Red comes out Stroma liquid Purple Goes in Red comes out Black is info Sugar= C6H12O6

Factors Affecting Photosynthesis a. Shortage of water b. Temperature: 32oF to 95oF is what enzymes work best at. c. Light Intensity d. CO2 concentration

What affects the rate of Photosynthesis?

Light intensity: as light increases, rate of photosynthesis increases… but this only works so long then it levels out.

Carbon Dioxide: As CO2 increases, rate of photosynthesis increases

Temperature: Temperature Low = Rate of photosynthesis low Temperature Increases = Rate of photosynthesis increases If temperature too hot, rate drops

Photosynthesis lab

Questions Spinach leaves are only one color (green), yet this part of the lab indicated more than one pigment can be found in within the spinach leaves. Explain why? Use your notes on why leaves change color (and the internet if you need) and try to identify the pigments that are present in your spinach leaf. Red cabbage leaves are only one main color (red), yet this part of the lab indicated more than one pigment can be found in within the cabbage leaves. Explain why? Use your notes on why leaves change color (and the internet if you need) and try to identify the pigments that are present in your cabbage leaf.

Spinach Carotene Xanthophyll Chlorophyll a Chlorophyll b

Red cabbage Betacyanin anthocyanin Chlorophyll a and b

Comparison Chart of the 2 Cycles

What other names does the cycle have? Light Cycle Light Dependent Cycle

What other names does the cycle have? Dark Cycle Light Independent Cycle Calvin Cycle

Where does the cycle run? Membrane of the Thylakoid

Where does the cycle run? Stroma of the Chloroplasts

When can the cycle run? Any time that there is water and sunlight.

When can the cycle run? Any time that there are charged batteries ATP and ADPH and CO2.

Why does the cell need this cycle? To change: ADP to ATP NADP+ to NADPH

Why does the cell need this cycle? To make sugar and other products that the cell needs for life processes.

What are the reactants? Light Water ADP NADP+

What are the reactants? CO2 ATP NADPH

What are the products? Oxygen (O2) ATP NADPH

What are the products? Sugar ADP NADP+

Other Notes on the Cycle Photo system 1 Photo system 2 Electron transport chain Uses sun to charge batteries

Other Notes on the Cycle Carbon fixation 6 turns to make 1 glucose Can happen in sunlight but does not need it to run.

Photosynthesis Worksheets

Why do the leaves change color in the fall?

1. What pigment do leaves get their color from? Chlorophyll a and b

2. What is the function of Chlorophyll? Absorbs sunlight and uses it to make food (glucose).

They move from the leaves to the branches, trunk and roots. 3. When trees are preparing for winter, where do the nutrients move to? They move from the leaves to the branches, trunk and roots.

4. When the nutrients leave the leaves what happens to the chlorophyll? It is not made by the leaves any more and current pigment in the leaves disintegrate.

5. How do the pigments come out of hiding? The dominant pigment… Chlorophyll is gone so other pigments show through.

6. What are the pigments that turn leaves scarlet, wine red and purple? Anthocyanin

7. How is the color of the leaves on the tree determined? It is inherited.

8. What factor influences whether these colors are dull or bright? Weather conditions.

9. How is the most brilliant shade developed in a tree? Temperatures from 32 to 45 F and limited rain.

10. How do the leaves fall off the branches? And within a few days or weeks, every leaf on these deciduous trees develops a thin bumpy line of cells that push the leaf, bit by bit, away from the stem. You can't see this without a microscope, but if you looked through one, you'd see those scissors cells lined right up. The scissor cells are stained red and mark the boundary between the branch (left) and the leaf stalk. 

Chapter 8 Photosynthesis Chapter Vocabulary Review

1. Where do autotrophs get energy to produce food? From the sun and water. (a) Mosses, ferns, and flowering plants (b) Kelp (c) Euglena (d) Cyanobacteria

2. How do living things use ATP? To store and release energy

3. How is one molecule of ATP formed from one molecule of ADP? When a cell has energy available it stores small amounts of it by adding a phosphate group to ADP.

4. How does a change from ATP to ADP provide an organism with energy? When ATP is changed to ADP a phosphate group is removed. This removal releases energy in the cell.

5. What are two ways in which cells use the energy provided by ATP? active transport across cell membranes and muscle contraction

Really Decomposers… Autotrophs Heterotrophs

H2O ATP NADPH

NADP+ ADP CO2

_______________________11 _______________________11. Molecule that absorbs light ___________________________12. Produces oxygen gas and converts ADP to ATP _______________________13. the region _______________________14. principal pigment found in plants _______________________15. process by which autotrophs use sunlight to make high-energy sugars C- pigment E- light dependent reaction B- stroma A- chlorophyll D- photosynthesis

Light Water CO2 O2 Gas Sugar

ATP Large protein that needs 3 phosphate groups to be charged. Quick Energy.

Thylakoid Photosynthetic membrane in the chloroplast where light cycle takes place.

NADP+ Carrier molecules transfers high energy e- from chloroplasts to sugars (glucose). This is the low charged form.

ATP Synthesis Protein uses H+ ions to produce ATP. Happens in Thylakoid membrane and it is the high charged form.

Calvin Cycle Energy from ATP and NADPH is used to build high energy sugars such as glucose The cycle runs 6 times to do this.

6. What is the difference between Autotrophs and heterotrophs? Autotrophs make there own food (glucose) like plants, algae Heterotrophs get nutrients from eating autotrophs.

7. in which part of photosynthesis is oxygen produced? Photolysis takes place in photosystem 1. This produces energy by splitting water molecules into gaseous oxygen and hydrogen ions.

8. What is the relationship between pigment and chlorophyll? pigments absorbs light & chlorophyll is the green pigment in plants.

9. How do the light-dependent reactions differ from the Calvin cycle ? light-dependent reaction uses energy from the sun to produce ATP & NADPH & oxygen gas (O2). Calvin cycle does not require light & uses ATP & NADPH for energy to produce glucose

10. What compounds are formed from carbon dioxide in the Calvin cycle. Monosaccharaides (glucose) Disaccharides (glucose + Fructose) Eventually polysaccharides

Photosynthesis Reviews http://www.mhhe.com/biosci/bio_animations/02_MH_Photosynthesis_Web/ http://www.phschool.com/science/biology_place/biocoach/photosynth/intro.html

Photosynthesis has 3 stages: Stage 1: absorption of light energy & chlorophyll vibrates and causes water to break apart. Stage 2: conversion of light energy into chemical energy, temporarily stored in ATP and NADPH Stage 3: storage of chemical energy in ATP and NADPH powers the formation of organic molecules

The light reactions convert solar energy to chemical energy Produce ATP & NADPH Light Chloroplast NADP ADP + P Calvin cycle Light reactions The Calvin cycle makes sugar from carbon dioxide

Steps of Photosynthesis The DARK Reactions= Calvin Cycle CO2 from atmosphere is joined to H from water molecules (NADPH) to form glucose Glucose can be converted into other molecules with yummy flavors!