I. PHOTOSYNTHESIS

Photosynthesis 6CO2 + 6H2O  C6H12O6 + 6O2 Photosynthesis: light energy is converted into chemical energy Carbon dioxide (CO2) requiring process that uses light energy (photons) and water (H2O) to produce organic macromolecules (glucose). 6CO2 + 6H2O  C6H12O6 + 6O2 glucose SUN light energy

Photosynthesis A two step anabolic reaction Light reactions – light energy converted into ATP and NADPH Calvin cycle – energy stored in ATP and NADPH is used to fix CO2 into organic compounds

II. Two Natures of Light Light acts like two things A wave A particle

Wave Nature Light is just a small sliver of something called electromagnetic radiation A form of energy that exhibits wavelike behavior as it travels through space Includes: Visible light Microwaves X-rays Radio waves UV rays Gamma rays

III. Electromagnetic Spectrum Sunlight contains a continuous range of wavelengths

Electromagnetic Spectrum Of course we know from getting tan and sunburnt that light isn’t the only electromagnetic radiation the sun emits

Particle Nature Einstein jumps in: He states that a beam of light can be thought of as a stream of tiny particles, or bundles of energy which he called photons A photon is a particle of electromagnetic radiation with no mass that carries a quantum of energy

Question: What do we call organisms in which photosynthesis take place?

Autotrophs Ex. plants, blue-green algae Autotrophs: self-producers. What organelle in autotroph cells is responsible for photosynthesis?

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

Thylakoid Thylakoid Membrane Granum Thylakoid Space

Question: Why are plants green?

III. Chlorophyll Molecules Chlorophyll a and b Located in the thylakoid membranes Chlorophyll pigments harvest light energy by absorbing certain wavelengths. blue-420 nm and red-660 nm are most important Plants are green because the green wavelengths are reflected, not absorbed.

Absorption of Chlorophyll violet blue green yellow orange red Absorption wavelength

Question: During the fall, what causes the leaves to change colors?

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

IV. Breakdown of Photosynthesis Two main parts (reactions). 1. Light Reaction (the electron flow) There are two reactions dependent on light. Produces energy from light (photons = solar energy) in the form of ATP and NADPH

1. Light Reaction (Electron Flow) Occurs in the thylakoid membranes Five main steps

Step 1 Occurs in the thylakoid membrane. Light energy is captured by Photosystem II (PSII) Contains chlorophyll a Light is “captured” = electrons are excited

Step 2 & 3 electrons now have enough energy to leave chlorophyll a in order to leave there has to be a molecule to accept them this is called the primary electron acceptor

Step 2 & 3 the primary electron acceptor donates the electron to the first of a series of molecules known as the Electron Transport Chain (ETC) each time it transfers an electron, energy is lost and used to pump a proton - H+ - into the thylakoid space

Step 4 light is also captured by chlorophyll a in PSI and it sends excited electrons down the ETC as well as electrons it received that had traveled through PSII ETC

Step 5 this ETC is on the stroma side of the thylakoid membrane and is used to combine electrons with H+ and NADP+ to produce a molecule of NADPH

When is O2 generated by photosynthetic organisms? The original e- that left PSII must be replaced. PSII gets its electrons when an enzyme splits H2O molecules from the inside of the thylakoid.

Chemiosmosis the movement of ions across a selectively permeable membrane, down their electrochemical gradient powers ATP synthesis located in the thylakoid membranes ETC and ATP synthase (enzyme) required to make ATP

Proton Gradient High [H+] Low [H+] There’s a H+ concentration gradient across the thylakoid membrane. the concentration of H+ is higher on the inside than the outside. High [H+] Low [H+]

Generation of ATP High [H+] Low [H+] ATP synthase uses the potential energy (PE) of this gradient to add a phosphate to ADP, creating ATP, when H+ moves through the ATP synthase complex. So, ATP synthase converts potential energy into stored chemical energy in the form of the newly formed bond in ATP. High [H+] Low [H+]

Generation of NADPH High [H+] Low [H+] some of these H+ that are moving into the stroma will then be used to generate NADPH. Both ATP and NADPH will then be used in the next set of reactions known as the Calvin cycle (carbon fixation). High [H+] Low [H+]

IV. Breakdown of Photosynthesis 2. Calvin cycle or dark reaction or carbon fixation or C3 fixation These reactions do not directly require light Uses energy (ATP and NADPH) from light rxn to make organic molecules, specifically sugar (glucose).

Calvin Cycle

Calvin Cycle includes the process of Carbon Fixation occurs in the stroma breaks the chemical bonds of ATP and NADPH forming ADP and NADP+ and uses this energy to fix the carbon from CO2 into organic compounds an important organic molecule formed is glucose

Recall: Chloroplast Stroma Outer Membrane Thylakoid Granum Inner Membrane

Calvin Cycle (C3 fixation)

Calvin Cycle

V. Photosynthesis 6CO2 + 6H2O  C6H12O6 + 6O2 When the light reactions and Calvin cycle are combined we get the equation below 6CO2 + 6H2O  C6H12O6 + 6O2 Glucose is used as the main organic compound generated in order to show the relationship between photosynthesis and cellular respiration. glucose SUN light energy

Cellular Respiration 1. g. Students know the role of the mitochondria in making stored chemical- bond energy available to cells by completing the breakdown of glucose to carbon dioxide. Mitochondria consist of a matrix where three-carbon fragments originating from carbohydrates are broken down (to CO2 and water) and of the cristae where ATP is produced. Cell respiration occurs in a series of reactions in which fats, proteins, and carbohydrates, mostly glucose, are broken down to produce carbon dioxide, water, and energy. Most of the energy from cell respiration is converted into ATP, a substance that powers most cell activities. 1. i.* Students know how chemiosmotic gradients in the mitochondria and chloroplast store energy for ATP production. Enzymes called ATP synthase, located within the thylakoid membranes in chloroplasts and cristae membranes in mitochondria, synthesize most ATP within cells. The thylakoid and cristae membranes are impermeable to protons except at pores that are coupled with the ATP synthase. The potential energy of the proton concentration gradient drives ATP synthesis as the protons move through the ATP synthase pores. The proton gradient is established by energy furnished by a flow of electrons passing through the electron transport system located within these membranes. 37

VI. Cellular Respiration Our Objectives: - Identify the process of how glucose is broken down in the first stage of cellular respiration. - Identify the steps of aerobic respiration - Describe how ATP is made in the second stage of cellular respiration. - Identify the role of fermentation in the second stage of cellular respiration. - Evaluate the importance of oxygen in aerobic respiration 11 38

Cellular Respiration vs Fermentation (Not in notes) Cellular Respiration – the transfer of energy from an organic compound into ATP Fermentation – the breakdown of carbohydrates by enzymes, bacteria, yeasts, or mold in the absence of oxygen 39

VI. Cellular Respiration Fermentation

VI. Cellular Respiration the process in which carbohydrates, mainly glucose, are broken down to make CO2, water, and energy. this energy will ultimately be stored in ATP takes place in the cell’s mitochondria 41

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VI. Cellular Respiration the creation of cellular energy, cellular respiration, has two stages Glycolysis – the breakdown of glucose 12 43

VI. Cellular Respiration Stage One: Breakdown of Glucose glycolysis: Glucose is broken down to pyruvate during glycolysis, making some NADH and ATP. Glycolysis does not require oxygen an anaerobic process occurs in the cytoplasm 13 44

VI. Cellular Respiration the creation of cellular energy, cellular respiration, has two stages Glycolysis – the breakdown of glucose Aerobic and Anaerobic Respiration – the production of ATP The second stage of cellular respiration is either aerobic respiration (in the presence of oxygen) or anaerobic respiration (in the absence of oxygen). A large amount of ATP is made during aerobic respiration. NAD+ is recycled during the anaerobic process of fermentation. 12 45

VI. Cellular Respiration Aerobic respiration Two steps: 1. Krebs Cycle (citric acid cycle) – takes place inside mitochondria -Mainly NADH is produced but also a little ATP to be used in the ETC - CO2 is generated at two points in this cycle during aerobic respiration. 14 46

VI. Cellular Respiration 2. Electron Transport Chain - During aerobic respiration, large amounts of ATP are made in an electron transport chain. - located in the inner membrane of mitochondria (known as the cristae) - creates a [H+] gradient - oxygen is the final acceptor of the electrons in the ETC - when O2 is the final acceptor this is known as aerobic respiration Stage Two: Production of ATP 14 47

VI. Cellular Respiration Anaerobic respiration Fermentation – the breakdown of carbohydrates when oxygen is not present fermentation follows glycolysis, regenerating NAD+ needed for glycolysis to continue. this allows ATP to still be generated by glycolysis when aerobic respiration is not possible generates ethanol and CO2 Lactic Acid Fermentation In lactic acid fermentation, pyruvate is converted to lactate (lactic acid). 15 48

VI. Cellular Respiration cont. Cellular Respiration is a metabolic process, like burning fuel. releases much of the energy in food to make ATP this ATP provides cells with the energy they need to carry out the activities of life. C6H12O6+O2 CO2 + H2O + ATP 1. g. Students know the role of the mitochondria in making stored chemical-bond energy available to cells by completing the breakdown of glucose to carbon dioxide. Mitochondria consist of a matrix where three-carbon fragments originating from carbohydrates are broken down (to CO2 and water) and of the cristae where ATP is produced. Cell respiration occurs in a series of reactions in which fats, proteins, and carbohydrates, mostly glucose, are broken down to produce carbon dioxide, water, and energy. Most of the energy from cell respiration is converted into ATP, a substance that powers most cell activities. 1. i.* Students know how chemiosmotic gradients in the mitochondria and chloroplast store energy for ATP production. Enzymes called ATP synthase, located within the thylakoid membranes in chloroplasts and cristae membranes in mitochondria, synthesize most ATP within cells. The thylakoid and cristae membranes are impermeable to protons except at pores that are coupled with the ATP synthase. The potential energy of the proton concentration gradient drives ATP synthesis as the protons move through the ATP synthase pores. The proton gradient is established by energy furnished by a flow of electrons passing through the electron transport system located within these membranes. 49

The connection between photosynthesis and cellular respiration 50

Review When oxygen is present, most of the ATP made in cellular respiration is produced by: A. The Krebs Cycle C. The Mitochondrial ETC B. Glycolysis D. Fermentation 51