Photosynthesis

Auxiliary Pigments Auxiliary pigments are pigments inside plant cells that absorb and reflect certain colors of the visible light spectrum, which is part of the electromagnetic spectrum. The role of auxiliary pigments in photosynthesis is huge. The auxiliary pigments pick up the energy from the state of chlorophyll and render it useful for absorbing light again as well as funneling the energy back into the light harvesting system. Without these pigments, photosynthesis would be ineffective because photosynthesis would be unable to use the energy of chlorophyll and light energy and there would be no color to give off from the process of photosynthesis. Some auxiliary pigments are:

Xanththophylls are yellow, brown, purple, or blue accessory pigments. They are found in the leaves of most plants and are synthesized within the plastids. They are involved in photosynthesis along with green chlorophyll. Xanthophylls, along with carotene pigments are seen when leaves turn orange in the fall. Not only that, Xanthophyll pigments make up the egg yolk of eggs. Xanthophylls are oxidized derivatives of carotenes. They are made up of hydroxyl groups and fairly polar; therefore making them go the farthest out of any pigment in paper chromatography. The cycle of Xanthophylls is primarily comprised of conversions of pigments from a non-energy-quenching form to an energy-quenching form. This is a way to reduce the amount of energy that reaches the photosynthetic reaction centers.

Carotenoids are found in all photoautotrophs and absorb blue-violet and blue-green that the chlorophylls a and b miss. They reflect red, yellow and orange wavelengths and there are two types of them. Carotenes are pure hydrocarbons and are orange photosynthetic pigments important for photosynthesis. Carotenes are responsible for the orange color of the carrot and many other fruits and vegetables. They contribute to photosynthesis by transmitting the light energy it absorbs to chlorophyll. Xanthophylls are yellow, brown, purple or blue accessory pigments that contain oxygen. Carotenoids are organic pigments that are naturally occurring in plants and some other photosynthetic organisms like algae, fungus and some bacteria. There are over 600 known carotenoids.

Chlorophyll a and b are pigments found in most plants. They both absorb mostly blue and red, and don’t absorb green, which is why most plants look green to us. There is a very slight difference between chlorophyll a and b. Along with helping color the plant, chlorophyll also helps the plant obtain energy. The only way to see the difference between the 2 chlorophyll’s is to do a chromatography experiment. This is when you put a piece of paper with the pigments that were taken from a protein, and put it into a solvent. This will clearly separate the 2 pigments.

Phycobilins are pigments that are usually found in red algae or certain bacterium. These pigments bond to certain water proteins that are called phycobiliproteins. The phycobilins pigment absorbs mostly red, orange, yellow, and green. In the algae the color depends on the depth of the water. For example, the algae in the shallow waters absorb the yellow and red light, while at deeper depths the algae absorbs mostly green light. Sometimes phycobilins are bonded to certain antibodies to help tag them in studies because of the florescence of the pigment. That means that at a certain wavelengths the pigment gives of a light, like a florescent light bulb. Anthocyanins are red to purple pigments that give many flowers their colors. Anthocyanin pigments help many pollinators locate flowers that contain them, and in fruits, the colorful skins may be recognized by animals. These animals will then eat the fruits and disperse the seeds. In photosynthetic tissues, Anthocyanins protect cells from photo-damage by absorbing blue-green light, therefore protecting the tissues from high light stress. This occurs in red juvenile leaves, autumn leaves, and broad-leaved evergreen leaves that turn red during the winter.

Photosynthesis runs on a fraction of the electromagnetic spectrum, the full range of energy radiating from the sun.
 * Electromagnetic Spectrum:** (from shortest wavelength to longest)
 * Gamma Rays
 * X-Rays
 * UV Radiation
 * Visible Light (used in photosynthesis)
 * infrared Radiation
 * Microwaves
 * Radio waves


 * Visible Light:**
 * Wavelengths human perceive as different colors
 * Violet (380 mm) to Red (750 mm)
 * Longer wavelengths, lower energy


 * Photons**:
 * Packets of light energy
 * Each type of photon has a fixed amount of energy


 * Pigment Structure:**
 * Light-catching part of a molecule often has alternating single and double bonds
 * These bonds contain electrons that are capable of being moved to higher energy levels by absorbing light


 * Variety of Pigments:**
 * Chlorophylls A and B
 * Carotenoids
 * Xanthophylls
 * Phycobilins
 * Anthocyanins

Steps in Photosynthesis:

FROM PHOTOSYNTHESIS QUIZ 2:

1. A process for separating the different types of molecules in a sample that relies on a solvent, a substrate is called **CHROMATOGRAPHY** 2. During our chromatography activity we calculated an **RF** value. This value is constant for any pair of molecule and solvent. 3. The complex that transfers light energy to chemical energy is called **PHOTO SYSTEMS/PHOTO COMPLEX** 4. During photosynthesis, chlorophyll looses its electrons, to replace the missing electrons, electrons are taken from a molecule of **WATER**, releasing **HYDROGEN IONS** and a single atom of **OXYGEN**. 5.In each turn of the Calvin Cycle one molecule of **CO2** is absorbed from the atmosphere and becomes part of a carbon based molecule 6. **THYLAKOID** is the membrane that is critical for the light Dependant reactions of photosynthesis 7. The 6-carbon molecule that is generated in every 6 turns of the Calvin cycle is **PHOSPHORYLATED GLUCOSE** 8. The 5-carbon sugar that is used and regenerated during each turn of the Calvin Cycle is **RIBULOSE** 9. **ATP** and **NADPH** are nucleotide compounds that transfer energy and electrons from the light dependent to the light independent reactions 10. Plants require **SUNLIGHT** and **WATER** and **OXYGEN** for photosynthesis 11. The molecules that capture the energy from the sun are called **PIGMENTS** 12. Photosynthesis is a process that changes the energy from the sun into **CHEMICAL** energy that can be moved around the cell 13. Plants make food using a defined section of this spectrum, called **VISIBLE LIGHT** 14. The sun emits a wide spectrum of energy called the **ELECTROMAGNETIC SPECTRUM**

The Basics

• Green plants capture energy from the sun • They turn CO2 into plant sugars • O2 is released in the process • This process is the basis of nearly all food webs on the planer (Exception: a few types of bacteria can oxidize minerals and make simple sugars)

Sunlight as Energy

• Photosynthesis runs on a fraction of the electromagnetic spectrum, or the full range of energy radiating from the sun

Electromagnetic Spectrum

• Shortest Wave Length

→longest wave length • Gamma Rays, X-rays, UV radiation, Visible Light, Infrared radiation, Microwaves, Radio Waves

Visible Light • Wavelengths human perceive as different colors • Violet (3800nm) to red (750nm) • Longer wavelengths, lower energy

Photons

• Packets of light energy • Each type of photon has fixed amount of energy • Photons having most energy travel as shortest wavelength (blue-green light) Pigments

• Light absorbing molecules • Absorb some wavelengths ad transmit others • Color you see are the wavelengths not absorbed

Pigment Structure

• Light catching part of molecule often has alternating single and double bonds • These bonds contain electrons that are capable of being moved to higher energy levels by absorbing light

Variety of Pigments

• Chlorophylls a and b • Cartenoids • Xanthophylls • Phycobilins • Anthocyanins

Chlorophylls

• Main pigments in most photoautotroph – organisms can make there own food from light

Carotenoids

• Found in all photoaytotrophs • Absord blue-violet and blue-green that chlorophylls miss • Reflect red, yellow, orange wavelengths • Two Types o Carotenes- pure hydrocarbons o Xanthophylls- contain oxygen

Xanthophylls

o Yellow Brown, purple, or blue accessory (help) pigments

Phycobilins and Antocyanins

o Red to purple pigments o Phylocobilins Found in red algai and cyanobacteria o Anthocyanins o Give many flowers their color

Carbon and Energy Sources o Photoautotrophs (plants, some bacteria and many protests) -Capture sunlight energy and use it to carry out photosynthesis -Carbon source in carbon dioxide -Energy Source is Sunlight o Heterotrophs (as in ?) -Get carbon and energy by eating autotrophs or one another

CALVIN CYCLE

6 carbon (co2) combines with a 5 6 carbon rubulose biphosphate in total 36 carbons. isn’t stable there are 12 molecules of 3 carbons. Turns into phosphoglycerate (PGA) Phospoglycerate gets an extra phosphate from ATP. 12 adp Phosphoglycerate needs 2 electrons. Need 12 NADPH. After the ATP gives a phosphate it turns into ADP After the NADPH gives 2 elcttrons it turns into NAD+ When everything is added the thing turns into a phosphoglyceradahydes. There are 12 PGAL Now there are 12 phosphoglyceradhyeds. 2 phosphoglyceades combine to make 1 glucose molecule. Now there are 10 phosphoglyceradahydes. Totlal of 30 carbons There are 10 3 carbon molecules 30 carbons 10 phosphate Kick out 4 phosphtaes and use there energy to bring 6 adp which brings 6 more phosphates. Now there are 12 phosphtes and 30 carbons. Phosphglyceradahydes are rearranged. Come up wit 6 5 carbon molecules called ribulose bisphosphate. still 30 carbons and 2 phosphate for each molecule.

Overall reactants of Calvin is Carbon dioxide ATP NADPH

Overall outputs Glucose ADP Nadp


 * 2 Major components**:
 * 1) Light-dependent reactions
 * 2) Light independent reactions (Calvin Cycle)


 * Light-dependent reactions**:


 * 1) Light is absorbed by the pigments and the energy is funneled to chlorophyll a
 * 2) Electrons in Chlorophyll are excited to a higher level and the electrons are passed to the electron transfer chain.
 * 3) The Light harvesting system replaces the missing e- by taking 2 e- from water. This releases 2 H+ ions and an O atom.
 * 4) Oxygen immediately combines with another O atom to become O2 gas which is released to the atmosphere
 * 5) The electrons (e-) are passed down the electron transport chain which pumps 2 hydrogen ions (H+) across the thylakoid membrane.
 * 6) The H+ (hydrogen ion) concentration inside the thylakoid compartment rises. The combination of the concentration and electrical gradients, propel H+ through ATP synthetase, driving ATP formation from ADP and P (phosphate).
 * 7) Photons also trigger the loose of e- from photosystem 1.
 * 8) The electron transfer chain ends with an molecule that passes a pair of e- to NADP+ and H+ thus forming NADPH.

Carbon fixation=Calvin Cycle (6 turns to make one glucose molecule):
 * Light Independent Reactions—The Calvin Cycle:**

1. 6 CO2 combine with 6 ribulose bisphosphate (RuBP) 2. The six 6-carbon molecules immediately split into 12 3-carbon phosphoglycerate (PGA) molecules. 3. Each PGA gets e- from NADPH and energy (not phosphate) from ATP forming 12 PGAL (phosphoglyceraldehydes) molecules. 4. 2 PGAL molecules combine to form phosphorylated-glucose (+ Pi) 5. Ten of the PGAL are phosphorylated by 6 ATP and rearranged to regenerate 6 RuBP 6. Then 6 RuBP molecules are ready for another round of the cycle.

The light emitted from the sun is portrayed as an electromagnetic spectrum. As you get towards the red side of the spectrum the wavelengths are longer, and as you move towards the blue they become shorter. In the middle of the spectrum you have the part that we see, called visible light. All of the different pigments have different wavelengths in the visible light spectrum. Depending on their high and low points will differ what colors are reflected by the plant. For example, chlorophyll a and b both have low points in the green area, meaning that they don’t absorb the color green. Because of this, they reflect green and that is why we see most plants as green. Photosynthesis only absorbs sunlight, and whatever wavelengths the pigment absorbs, and reflects whatever it doesn’t absorb, and all plants absorb the sunlight from the visible light spectrum to help photosynthesis.
 * Question: What does photosynthesis have to do with wavelength and visible light?**

The inputs for the light-dependent reactions are sunlight, and H2O. The outputs for light-dependent reactions are ATP, NADPH and Oxygen gas. (There is only one atom of oxygen released for every H2O that is used. However, the reaction happens with multiple photosystems concurrently so there are lots of water molecules being split. Since oxygen does not like to be in a one atom state, each oxygen molecule will immediately pair with another to form O2 or oxygen gas). The inputs for the light-independent reactions are ATP, NADPH and CO2. The outputs for light-independent reactions are glucose and H2O.
 * Question: What are the inputs and outputs for each set of reactions?**

1.** Auxiliary pigments-pigments inside plant cells that absorb and reflect certain colors of the visible light spectrum
 * IMPORTANT VOCABULARY:
 * 2.** Xanththophylls-yellow, brown, purple, or blue accessory pigments
 * 3.**Caroetnoids-absorb blue-violet and blue-green that the chlorophylls a and b miss. They reflect red, yellow and orange wavelengths
 * 4.** Chlorophylls A and B - absorb mostly blue and red, and don’t absorb green
 * 5.** Phycobilins-absorbs mostly red, orange, yellow, and green
 * 6.** Photons- packets of light energy
 * 7.** Chromatography-process for separating different types of molecules in a sample
 * 8.** RF value is constant for any pair of molecule and solvent
 * 9.** Photosystem/photocomplex- complex that transfers light energy to chemical energy
 * 10.** Thylakoid-membrane that is critical for the light dependant reactions of photosynthesis
 * 11.** Phosphorylated glucose-6 carbon molecule that is generated in every 6 turns of the Calvin Cycle
 * 12.** Ribulose- 5 carbon sugar that is used and regenerated during each turn of the Calvin Cycle
 * 13.** Pigments-molecules that capture energy from the sun
 * 14.** Visible light-plants use this to make food
 * 15.** Electromagnetic Spectrum-wide spectrum of energy emitted by the sun