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Photosynthesis and Cellular Respiration

Discover the basics of photosynthesis, where plants and other autotrophs convert light energy into chemical energy, using pigments like chlorophyll. Learn about the importance of the sun and how it powers the process of photosynthesis. Explore the light-dependent and dark reactions, electron transport chains, and the production of ATP and NADPH.

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Photosynthesis and Cellular Respiration

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  1. Photosynthesis and Cellular Respiration

  2. Light Energy Harvested by Plants & Other Photosynthetic Autotrophs 6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2

  3. 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 (b) Kelp (a) Mosses, ferns, and flowering plants

  4. THE SUN: WHY IS IT IMPORTANT? Source of light energySource of heat energyGravitational attractionSource of radiationDay and night Source of all energy(electricity) Source of food for all organisms!!!!

  5. SUN’S SPECTRUM

  6. Pigment and Light Energy from the Sun travels to the Earth as light. We see sunlight as “white light” which is really different wavelengths(ROYGBIV). Plant gather the Sun’s energy with light-absorbing molecules called PIGMENTS. Pigments: photosynthetic organisms capture energy using pigments. Chlorophyll: pigments plants use to absorb light energy. Plant have different pigments.

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

  8. THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED • Chloroplasts absorb light energy and convert it to chemical energy. They absorb the reds and blue. Reflects the green. • That is why they look green. Reflected light Light Absorbed light Transmitted light Chloroplast

  9. Different pigments absorb light differently

  10. Different Pigments • Chlorophyll a – green pigments in plants and bacteria • Chlorophyll b in green algae • Carotenoids – orange, red, yellow when chloroplast die in plants. Chlorophyll breaks down first in the fall so we see these colors. • Xanthophyll – yellow pigments in diatoms(protists) Figure 7.7

  11. Why are Chloroplast Important? The chloroplasts absorb the Sun’s energy and use this energy to excite electrons which powers photosynthesis. To break apart water and carbon Dioxide, you must have energy!!!!

  12. ATP for energy ATP powers cellular work- made in photosynthesis amd cellular respiration A cell does three main kinds of work: Mechanical work, beating of cilia, contraction of muscle cells, and movement of chromosomes(produces heat) Transport work, pumping substances across membranes against the direction of spontaneous movement Chemical work, driving endergonic reactions such as the synthesis of polymers from monomers

  13. High Energy Electrons and Molecules Once the sun’s energy has been trapped and excited an electron, what happens to it? Electron Carrier: a molecule that picks up the electron and uses this energy to break apart bonds. Examples of electron carriers: NADP and ATP NADP captures two electrons of H and becomes NADPH. ADP becomes ATP!!!

  14. How Does ATP Work? So what? Energy is stored in these bonds. So? The breaking of the chemical bond releases the energy ATP + H2O→ ADP + P + ENERGY ATP is made in photosynthesis and respiration!!! ATP (adenosine triphosphate) is a a molecule that carries energy that cells can use.

  15. How Does ATP Work? The bonds between phosphate groups can be broken by hydrolysis which produces energy!!! ATP has 3 phosphate groups The bond to the third bond is easily broken. When the third bond is broken, energy is released. Becomes ADP – no energy!!

  16. Photosynthesis Photosynthesis uses the energy of the sunlight to convert water and carbon dioxide(reactants) into high-energy sugars and oxygen(products) Photosynthesis occurs in the parts of the chlorplasts. There are three parts involved.

  17. Parts of the Chloroplasts • Thylakoids: flat compartments in the chloroplast that contain chlorophyll. LIGHT DEPEDENT REACTION occurs here. • Grana: are stacks of thylakoids. • Stroma: fluid that is all around the grana inside the chorplast. LIGHT INDEPENDENT REACTION occurs here.

  18. Occurs in the membrane of the thylakoids

  19. Overview of Photosynthesis Step 1 – Light dependent reaction(depends on Light) Traps the sunlight and energy is moved along the thylakoid membrane. Water is broken in to O and H by the electrons that are in ATP and NADPH required for dark reaction. Oxygen given off as waste. Photosystem I and photosystem II - pigments Step 2 – Dark reaction(Calvin Cycle) Carbon Dioxide now is added to cycle to build glucose.Uses ATP and electrons from light reaction to make glucose.

  20. Electron transport chains and photosystems • Photosystems: cluster of chlorophyll and proteins absorb the sun’s energy and generate the high energy electrons that are passed to the electron carrier molecules. • Their energy ends up in ATP and NADPH

  21. Step 1 – Light Dependent Reaction • The light reactions convert solar energy to chemical energy. Takes place in thylakoids. • Photosystem II and electron transport • 1. chlorophyll absorbs the sun’s energy. • 2. Energy as electrons is moved along the membrane(electron transport chain) • 3. Water is split into H and O. O released as waste through stoma. • 4. H is pumped over and over again in the membrane until they build up. Photosynthesis

  22. Plants produce O2 gas by splitting H2O • The O2 liberated by photosynthesis is made from the oxygen in water (H+ and e-)

  23. Electron Transport Chain When the electrons are excited from the light reaction, they are passed along the membrane through the protein pumps. They passed from Photosystem I to photosystem II.

  24. Photosynthesis Photosystem I 1. Electrons from photosytem II is moved along the membrane to photosystem I. 2. Chlorophyll continue to adsorb sunlight and free electrons. 3. Electrons are added to NADPH which is the energy carrier for the rest of photosynthesis. 4. The electrons are pumped though a channel as part of an enzyme ATP synthase to make ATP.

  25. Summary of Light-dependent Reaction * Energy is captured from sunlight and transferred to electrons(electron transport chain). Water molecule pulled apart to provide H ions. The ions are used to make ATP and NADPH. Need: sunlight and water Produce: energy carrying molecules and oxygen(waste).

  26. The production of ATP Thylakoidcompartment(high H+) Light Light Thylakoidmembrane Antennamolecules Stroma(low H+) ELECTRON TRANSPORT CHAIN PHOTOSYSTEM II PHOTOSYSTEM I ATP SYNTHASE

  27. Summary—Light Dependent Reactions a.Overall input light energy, H2O. b. Overall output ATP, NADPH, O2.

  28. AN OVERVIEW OF PHOTOSYNTHESIS • Step 2 – Light Independent Reaction – CALVIN CYCLE Occurs in the stroma. • The Calvin cycle makes sugar from carbon dioxide • 1.ATP generated by the light reactions provides the energy for sugar synthesis • 2.The NADPH produced by the light reactions provides the electrons for the reduction of carbon dioxide to glucose. Carbon Dioxide is built to make a 6 carbon sugar called glucose. • END GOAL – to break carbon dioxide down and combine into glucose!!! Need energy to do this!! That is why ATP and NADPH was made!!

  29. Light Independent Reaction Overview • 1. Carbon dioxide added:Carbon Dioxide enters the • plant from the atmosphere. Bonds with a 5-carbon sugar. • Three-carbon molecules formed: ATP and NADPH • use enzymes in the stroma to split the six carbon into • 3 carbon sugars. • 3. Three-carbon molecules exit: Most 3 carbon stay in cycle. • When 2 leave, they form glucose. • Three-carbon molecules recycled: Energy from ATP • Change 3carbon molecules back into 5 carbon to start the • cycle over again. • *Energy provided by Light dependent reaction. • The plants uses the carbohydrates to meet its energy needs • to make all of the macromolecules that it needs(proteins, lipids, carbs).

  30. Overview Calvin Cycle In put: ATP, NADPH, and Carbon dioxide Output: GLUCOSE!! The end goal – Make glucose from the SUN!!

  31. Harvesting Chemical Energy Energy enters food chains (via autotrophs) we can look at how organisms use that energy to fuel their bodies. • Plants and animals both use products of photosynthesis (glucose) for metabolic fuel • Heterotrophs: must take in energy from outside sources, cannot make their own e.g. animals

  32. Cellular Respiration RELEASES CHEMICAL ENERGY FROM SUGARS AND OTHER CARBON-BASED MOLECULES TO MAKE ATP WHEN OXYGEN IS PRESENT!!!!NO OXYGEN – FERMENTATION!!!!

  33. The Purpose of Cellular Respiration It is to make and break bonds to generate ATP and electrons. You end up with ATP, H ions and electrons. The electrons are sent to the Electron Transport Chain where they help to make ATP through ATP synthase. ****Hydrogen ions are bonded with oxygen to make water which is used in photosynthesis.

  34. How do we make atp? Just like in photosynthesis. ATP is made by pumping H across ATP synthase to attach a P onto ADP. This is the goal of cellular respiration.

  35. Relationship between Photosynthesis and Cellular Respiration The products on one are used for the other to produce ATP from the Sun! Creates the Carbon- Oxygen Cycle!!!

  36. Carbon Oxygen Cycle

  37. NADP and NAD Photosynthesis use the electron carrier - NADP (nicotinmide adenine dinucleotide phosophate) Cellular respiration uses - NAD ( nicotinmide adenine dinucleotide)

  38. Cellular Respiration Overview • Transformation of chemical energy in food into chemical energy cells can use: ATP • These reactions proceed the same way in plants and animals. Process is called cellular respiration • Overall Reaction: • C6H12O6 + 6O2 → 6CO2 + 6H2O

  39. Cellular Respiration • Glycolysis – Occurs before Cell. Resp. • Krebs Cycle (Citric Acid Cycle) • Electron Transport Chain (ETC) Glucose Krebs cycle Electrontransport Glycolysis Fermentation (without oxygen) Alcohol or lactic acid

  40. Overall Reaction C6H12O6 + 6O2→ 6CO2 + 6H2O + 38 ATP Overall this is a three stage process Glycolysis: before cellular respiration Occurs in the cytoplasm Glucose is broken down Krebs Cycle Breaks down pyruvate into CO2 Occurs in mitochondrial matrix Electron Transport Chain ATP is synthesized - Occurs in mito membrane

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