MAIN SOURCE OF ENERGY FOR LIFE ON EARTH? THE SUN!!

THE BASICS OF PHOTOSYNTHESIS Almost all plants are photosynthetic autotrophs, as are some bacteria and protists Autotrophs generate their own organic matter through photosynthesis Sunlight energy is transformed to energy stored in the form of chemical bonds (c) Euglena (d) Cyanobacteria (a) Mosses, ferns, and flowering plants (b) Kelp

Light Energy Harvested by Plants & Other Photosynthetic Autotrophs 6 CO 2 + 6 H 2 O + light energy C 6 H 12 O 6 + 6 O 2

Energy needs of life All life needs a constant input of energy Heterotrophs (Animals) get their energy from eating others eat food = other organisms = organic molecules make energy through respiration Autotrophs (Plants) get their energy from self get their energy from sunlight build organic molecules (food) from CO 2 make energy & synthesize sugars through photosynthesis

Energy needs of life Heterotrophs consumers Animals Protists fungi most bacteria Autotrophs producers plants photosynthetic bacteria (blue-green algae)

How are they connected? Heterotrophs making energy & organic molecules from ingesting organic molecules glucose + oxygen carbon + water + energy dioxide C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + ATP exergonic Autotrophs making energy & organic molecules from light energy carbon + water + energy glucose + oxygen dioxide 6CO 2 + 6H 2 O + light C 6 H 12 O 6 6O energy + 2 endergonic Where s the ATP?

Energy cycle sun Photosynthesis plants CO 2 H 2 O glucose O 2 animals, plants Cellular Respiration The Great Circle of Life,Mufasa! ATP

Food Chain

THE FOOD WEB

What does it mean to be a plant Need to collect light energy transform it into chemical energy store light energy in a stable form to be moved around the plant & also saved for a rainy day need to get building block atoms from the environment CO C,H,O,N,P,S 2 produce all organic molecules needed for growth carbohydrates, proteins, lipids, nucleic acids ATP glucose N P K H 2 O

Plant structure Obtaining raw materials sunlight leaves = solar collectors CO 2 stomata = gas exchange H 2 O uptake from roots nutrients N, P, K, S uptake from roots

stomate transpiration

WHY ARE PLANTS GREEN?

Electromagnetic Spectrum and Visible Light Gamma rays X-rays UV Infrared & Microwaves Radio waves Visible light Wavelength (nm)

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

The feathers of male cardinals are loaded with carotenoid pigments. These pigments absorb some wavelengths of light and reflect others. Sunlight minus absorbed wavelengths or colors equals the apparent color of an object.

Why are plants green? Transmitted light

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

THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED Chloroplasts absorb light energy and convert it to chemical energy Light Reflected light Absorbed light Transmitted light Chloroplast

What wavelengths of light have the most energy? Red, blues, violets = most Yellows & greens = least

AN OVERVIEW OF PHOTOSYNTHESIS Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water Carbon dioxide Water Glucose Oxygen gas PHOTOSYNTHESIS

Who do we have to thank for all of this?? Many scientists but 3 got the ball rolling. Jan van Helmont - water made up mass Joseph Priestley - mint freshened air under jar Jan Ingenhousz - plants needed light to remain alive The complete timeline?

What are we looking at today? Stomata (stoma) Pores in a plant s cuticle through which water and gases are exchanged between the plant and the atmosphere. Oxygen (O 2 ) Carbon Dioxide (CO 2 ) Guard Cell Guard Cell

Have the ability to open and close. Closed at night & dry days to save water. Open to allow exchange of CO 2 and O 2 When water plentiful guard cells swell. When dry, vacuoles shrink closing stoma

stomate transpiration

The Photosynthesis Equation Light energy O 2 ADP NADP + Sugar CO 2 + H 2 0

Light and Pigments What is the role of light and chlorophyll in photosynthesis?

Light and Pigments Light and Pigments How do plants capture the energy of sunlight? In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll.

Light and Pigments Plants gather the sun's energy with light-absorbing molecules called pigments. The main pigment in plants is chlorophyll. There are two main types of chlorophyll: chlorophyll a chlorophyll b

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

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

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

Other pigments in plants Carotenoids-orange Absorb: bluegreen Reflect: yellow-orange

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

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

Estimated Absorption (%) Light and Pigments Chlorophyll absorbs light well in the blue-violet and red regions of the visible spectrum. 100 80 60 Chlorophyll b Chlorophyll a 40 20 0 400 450 Wavelength 500 550 600 (nm) 650 700 750 Wavelength (nm)

Estimated Absorption (%) Light and Pigments Chlorophyll does not absorb light well in the green region of the spectrum. Green light is reflected by leaves, which is why plants look green. 100 80 60 40 Chlorophyll b Chlorophyll a 20 0 400 450 500 550 600 650 700 750 Wavelength (nm)

Light and Pigments Light is a form of energy, so any compound that absorbs light also absorbs energy from that light. When chlorophyll absorbs light, much of the energy is transferred directly to electrons in the chlorophyll molecule, raising the energy levels of these electrons. These high-energy electrons are what make photosynthesis work.

8-3 The Reactions of Photosynthesis

Inside a Chloroplast Inside a Chloroplast In plants, photosynthesis takes place inside chloroplasts. Plant Chloroplast Plant cells

Inside a Chloroplast Chloroplasts contain thylakoids saclike photosynthetic membranes. Single thylakoid Chloroplast

Inside a Chloroplast Thylakoids are arranged in stacks known as grana. A singular stack is called a granum. Granum Chloroplast

Inside a Chloroplast Proteins in the thylakoid membrane organize chlorophyll and other pigments into clusters called photosystems, which are the lightcollecting units of the chloroplast. Photosystems Chloroplast

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

Inside a Chloroplast The reactions of photosystems include: the light-dependent reactions and the light-independent reactions, or Calvin cycle. The light-dependent reactions take place within the thylakoid membranes. The Calvin cycle takes place in the stroma, which is the region outside the thylakoid membranes.

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

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

Inside a Chloroplast Light H 2 O CO 2 NADP + ADP + P Lightdependent reactions Calvin Cycle cycle Chloroplast O 2 Sugars

Electron Carriers Electron Carriers When electrons in chlorophyll absorb sunlight, the electrons gain a great deal of energy. Cells use electron carriers to transport these high-energy electrons from chlorophyll to other molecules.

THYLAKOIDS

Summary IN

Summary OUT

Electron Carriers One carrier molecule is NADP +. Electron carriers, such as NADP +, transport electrons. NADP + accepts and holds 2 high-energy electrons along with a hydrogen ion (H + ). This converts the NADP + into NADPH.

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

Overview of Photosynthesis

What happens here? Light Dependent Reaction (LDR) Converts light energy to chemical energy + O 2 Light Independent Reaction (LIR) Assembles sugar molecules using CO 2

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 LIR sugar NADPH Also O 2

Electron Carriers The conversion of NADP + into NADPH is one way some of the energy of sunlight can be trapped in chemical form. The NADPH carries high-energy electrons to chemical reactions elsewhere in the cell. These high-energy electrons are used to help build a variety of molecules the cell needs, including carbohydrates like glucose.

Light-Dependent Reactions What happens in the light-dependent reactions?

Light-Dependent Reactions Light-Dependent Reactions The light-dependent reactions require light. The light-dependent reactions produce oxygen gas and convert ADP and NADP + into the energy carriers ATP and NADPH.

Light-Dependent Reactions

Light-Dependent Photosynthesis begins when Reactions pigments in photosystem II absorb light, increasing their energy level. Photosystem II

Light-Dependent These high-energy electrons Reactions are passed to the electron transport chain. Photosystem II High-energy electron Electron carriers

Light-Dependent Enzymes on the thylakoid Reactions membrane break water molecules into: Photosystem II 2H 2 O High-energy electron Electron carriers

Light-Dependent hydrogen ions Reactions oxygen atoms energized electrons Photosystem II 2H 2 O + O 2 High-energy electron Electron carriers

Light-Dependent Reactions The energized electrons from water replace the high-energy electrons that chlorophyll lost to the electron transport chain. Photosystem II 2H 2 O + O 2 High-energy electron

Light-Dependent Reactions As plants remove electrons from water, oxygen is left behind and is released into the air. Photosystem II 2H 2 O + O 2 High-energy electron

Light-Dependent Reactions The hydrogen ions left behind when water is broken apart are released inside the thylakoid membrane. Photosystem II 2H 2 O + O 2 High-energy electron

Light-Dependent Reactions Energy from the electrons is used to transport H + ions from the stroma into the inner thylakoid space. Photosystem II 2H 2 O + O 2

Light-Dependent Reactions High-energy electrons move through the electron transport chain from photosystem II to photosystem I. Photosystem II 2H 2 O + O 2 Photosystem I

Light-Dependent Reactions Pigments in photosystem I use energy from light to re-energize the electrons. 2H 2 O + O 2 Photosystem I

Light-Dependent Reactions NADP + then picks up these high-energy electrons, along with H + ions, and becomes NADPH. 2H 2 O + O 2 2 NADP + 2 NADPH 2

Light-Dependent Reactions As electrons are passed from chlorophyll to NADP +, more H + ions are pumped across the membrane. 2H 2 O + O 2 2 NADP + 2 NADPH 2

Light-Dependent Reactions Soon, the inside of the membrane fills up with positively charged hydrogen ions, which makes the outside of the membrane negatively charged. 2H 2 O + O 2 2 NADP + 2 NADPH 2

Light-Dependent Reactions The difference in charges across the membrane provides the energy to make ATP. 2H 2 O + O 2 2 NADP + 2 NADPH 2

Light-Dependent H + ions cannot cross the membrane Reactions directly. ATP synthase + O 2 2H 2 O 2 NADP + 2 NADPH 2

The cell membrane contains a protein called ATP synthase that allows H + ions to pass through it. Light-Dependent Reactions ATP synthase 2H 2 O + O 2 2 NADP + 2 NADPH 2

As H + ions pass through ATP synthase, the protein rotates. Light-Dependent Reactions ATP synthase + O 2 2H 2 O 2 NADP + 2 NADPH 2

As it rotates, ATP synthase binds ADP and a phosphate group together to produce ATP. Light-Dependent Reactions ATP synthase 2H 2 O + O 2 2 NADP + ADP 2 NADPH 2

Because of this system, light-dependent electron transport produces not only high-energy electrons but ATP as well. Light-Dependent Reactions ATP synthase 2H 2 O + O 2 2 NADP + ADP 2 NADPH 2

Light-Dependent Reactions The light-dependent reactions use water, ADP, and NADP +. The light-dependent reactions produce oxygen, ATP, and NADPH. These compounds provide the energy to build energycontaining sugars from low-energy compounds.

The Calvin Cycle What is the Calvin cycle?

Calvin Cycle Occurs in stroma of chloroplasts

7.11 Review of Photosynthesis

Summary: Calvin Cycle

Overall Equation

The Calvin Cycle The Calvin Cycle ATP and NADPH formed by the light-dependent reactions contain an abundance of chemical energy, but they are not stable enough to store that energy for more than a few minutes. During the Calvin cycle plants use the energy that ATP and NADPH contain to build high-energy compounds that can be stored for a long time.

The Calvin Cycle The Calvin cycle uses ATP and NADPH from the light-dependent reactions to produce high-energy sugars. Because the Calvin cycle does not require light, these reactions are also called the lightindependent reactions.

The Calvin Cycle Six carbon dioxide molecules enter the cycle from the atmosphere and combine with six 5-carbon molecules. CO 2 Enters the Cycle

The Calvin Cycle The result is twelve 3-carbon molecules, which are then converted into higher-energy forms.

The Calvin Cycle The energy for this conversion comes from ATP and high-energy electrons from NADPH. Energy Input 12 12 ADP 12 NADPH 12 NADP +

The Calvin Cycle Two of twelve 3-carbon molecules are removed from the cycle. Energy Input 12 12 ADP 12 NADPH 12 NADP +

The Calvin Cycle The molecules are used to produce sugars, lipids, amino acids and other compounds. 12 12 ADP 12 NADPH 12 NADP + 6-Carbon sugar produced Sugars and other compounds

The Calvin Cycle The 10 remaining 3-carbon molecules are converted back into six 5- carbon molecules, which are used to begin the next cycle. 12 6 ADP 6 12 ADP 12 NADPH 12 NADP + 5-Carbon Molecules Regenerated Sugars and other compounds

The Calvin Cycle The two sets of photosynthetic reactions work together. The light-dependent reactions trap sunlight energy in chemical form. The light-independent reactions use that chemical energy to produce stable, highenergy sugars from carbon dioxide and water.

Factors Affecting Photosynthesis Factors Affecting Photosynthesis Many factors affect the rate of photosynthesis, including: Water Temperature Intensity of light

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

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

REVIEW ALL OF CHAPTER 8

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

ANSWER: C. oxygen concentration

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

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

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

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

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 CO 2 Releasing O 2

ANSWER Forming ATP NADP+ to NADPH Releasing O 2

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

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

ANSWER Stroma of chloroplasts

QUIZ TIME What is the name of the enzyme that causes CO 2 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 CO 2 NADP+

ANSWER ADP NADP+ glucose