PLB 115 1st Edition Lecture 10Previous Notes’ OutlineI. Cell RespirationII. Aerobic RespirationIII. Glucose oxidationIV. GlycolysisV. Kreb’s CycleVI. Electron-Transport System VII. Metabolization of other MoleculesVIII. Fat RespirationIX. Protein RespirationX. Anaerobic Cellular RespirationXI. Alcoholic FermentationXII. Lactic Acid FermentationCurrent Notes’ OutlineII. Photosynthesis overviewa. Photosynthesisb. Events: Light-capturing, Light-dependent, Light-independentIII. Light-capturing eventsa. Accessory pigmentsIV. PhotosystemsV. Light-dependent eventsVI. Light-independent eventsVII. Light Dependent Reactions BasicsVIII. Electron Transport Chain & ATP SynthesisIX. Interactions of PSII & PSIX. Plant MetabolismPhotosynthesis- During photosynthesis organisms use light’s energy to make high-energy organic molecules - Photosynthetic autotrophs (plants, algae, bacteria) can make own food source with lighto 99% of life on earth relies on photosynthesis for energy (heterotrophs eat autotrophs)PhotosynthesisThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- The energy in light used to make ATP - ATP’s energy used to make organic molecules - Occurs in chloroplasts that contain thylakoids which have chlorophyll: pigment capturinglight’s energy - Stack of thylakoids is a granum & granum are suspended in fluid space called stromaChemical equation: Light energy + carbon dioxide + water  glucose and oxygenThree events of photosynthesisLight-capturing events - Chlorophyll absorbs red & blue wavelengths of light & some electrons become excited. Light-dependent reactions - Use energy in excited electrons to make ATP & NADPH (Nicotinamide adenine dinucleotide phosphate)Light-independent reactions - ATP & NADPH used to reduce carbon dioxide to make glucoseLight Capturing EventsVisible light- Combinations of different wavelengths of light can be seen as different colors- Pigment molecules absorb certain wavelengths of light (red and blue), non-absorbed is reflected (green) & visibleChlorophyll pigment has two forms: a & b that absorb light in blue & red pieces of light spectrumAccessory pigments - Carotenoids: Absorb blue & green wavelengths, reflect orange & yellowo Found in leaves, masked by chlorophyll, but show in autumn when chlorophyll disintegrates- Chlorophyll & accessory pigments organized in photosystems that harvest energy from many wavelengths of light - When pigments absorb light, some electrons become excitedLight-Capturing Events- Light is packaged as photons & each photon has a distinct wavelength - Energy in photon is related to its wavelength- When a photon hits a pigment molecule, electrons are excited (jump up to higher energy level)PhotosystemsTwo photosystems: I & II- Where light-capture takes place- Made up of antenna complexes & reaction center- Found in thylakoid membranes- Energy is captured in many different wavelengths of light & passed to reaction centerLight-Dependent Reactions- Excited electrons from chlorophyll passed through electron transport chaino Energy released used to pump protons up concentration gradient- When protons diffuse through ATP synthase- ATP is made- Excited electrons passed to NADP+ to make NADPH- Water is split, electrons donated to chlorophyll to replace donated electrons & oxygen is produced- ATP & NADPH move to the stroma to be used in dark reactionso All occurs in thylakoid membrane Light-Independent Reactions (Happen in thylakoid membrane)- ATP & NADPH provide energy & electrons needed to build sugar from carbon dioxide- CO2 captured by enzyme RuBisCO (6-carbon molecule combining Carbon Dioxide & Ribulose)o Immediately broken down into two 3-carbon molecules energized by ATP  NADPH used to reduce these molecules- Glyceraldehyde-3-phosphate formed to make sugars, fats, proteinsLight Dependent Reactions Basics- Photosystem II (PSII) - Happens 1st - Donates its excited electrons to electron transport chain - Splits water to replace electrons it donated - Oxygen (O2) is releasedPhotosystem I (PSI)- Donates its excited electrons to NADP+ to form NADPH- NADPH released into the stroma - Accepts electrons from the electron transport chain to replace the electrons it donated Electron Transport Chain & ATP Synthesis- Calvin Cycle/dark reactions- Happens in StromaUses - CO2 (from the atmosphere) - ATP & NADPH (from the light-independent reactions) - Ribulose (recycled) Interactions of PSII & PSIBetween them:- Electrons are passed through an electron transport chain (ETC) o Releases energy used to pump protons from the stroma into the thylakoid space- Creates a proton concentration gradient o Protons diffuse through ATP synthaseo ATP synthase makes ATP that is released into the stromaPlant Metabolism- Plant cells can use organic molecules produced in photosynthesis to make o Fats, proteins, carbohydrateso Vitamins o Toxins for their own protection  Many are useful medicines Some used as natural insecticidesThe circle of life: Animals get sugar, oxygen, amino acids, fats, and vitamins from plants. Plants get carbon dioxide, water, & nitrogen from animalsAll organisms