Energy & Photosynthesis

1. Energy& Photosynthesis

2. What is energy and what is it needed for?

3. Energy • Energyis the ability to cause matter to move or to change • The ability to do work • Why do our cells require energy? • Growth & repair • Active transport • Reproduction • Synthesis of molecules

4. Does food, which contains sugar and other carbon-based molecules give you energy?

5. Does food provide energy? Yes & No! • All carbon-based molecules in food STORE chemical energy in their bonds! • Remember, carbohydrates & lipids are the most important energy sources in food you eat • However, the energy in food is only usable after these molecules are broken down during digestion and a series of other chemical reactions

6. ATP: The Energy Molecule • ATP = adenosine triphosphate • All cells use chemical energy carried by ATP! • Monomers- single building blocks: • Adenine: a nitrogenous base • Ribose: 5 Carbon sugar • 3 phosphate groups

7. Where is Energy stored in the ATP molecule? • Energy is in the chemical bonds between the phosphates • The bond holding the third phosphate group is unstable and very easily broken • The removal of the third phosphate group releases energy

8. ADP Molecule • Adenosine diphosphate or ADP • Has 2 phosphate groups • When a phosphate is removed, energy is released and ATP becomes ADP

9. Phosphorylation & ATP/ADP Cycle • When a cell has energy available, it can store small amounts of it by phosphorylation (the addition of a phosphate group) to the ADP molecule, thus producing ATP • This requires a large, complex group of proteins

10. ADP ATP Low-Energy Molecule High-energy molecule

11. What makes these cells so important to many other organisms? • These diatoms are single-celled algae that use the process of photosynthesis to store chemical energy in sugars. • Animals eat photosynthetic organisms such as plants & algae to get this chemical energy • Photosynthetic organisms also produce the oxygen that is required to release much of the chemical energy in sugars

12. Plants are Energy Producers • Like animals, plants need energy to live • unlike animals, plants don’t need to eat food to make that energy • Plants produce the source of chemical energy for themselves and other organisms • animals are consumers (heterotrophs) • plants are producers (autotrophs/photoautotrophs)

13. How do autotrophs provide energy? • Plants, some bacteria, and protists are the main sources of chemical energy for most organisms • These autotrophs convert solar energy into chemical energy (sugars) • Ex. glucose, sucrose, cellulose & starch sun ATP sugars

14. How do we perceive colors?

15. Light energy Sunlight includes a wide range of radiant energy, such as ultraviolet radiation, microwaves, and the visible light spectrum that lets you see

16. Wavelengths • Electromagnetic radiation – form of energy that exhibits wavelike behavior as it travels through space • Longer wavelength = lower energy • Shorter wavelength =higher energy

17. Visible Light Spectrum •  Visible light appears white, but it is made up of several colors, or wavelengths of light • The surface of an object reflects some colors and absorbs all the others. • We perceive only the reflected colors. • An object appears white when it reflects all wavelengths and black when it absorbs them all.

18. What role do pigments play in the process of photosynthesis?

19. Light and Pigments • Since light is a form of energy, any compound that absorbs light also absorbs the energy from that light • Chlorophyll is a molecule in chloroplasts that absorbs some of the energy in visible light • There are two main types of chlorophyll (a & b) which, together, absorb mostly red and blue wavelengths of visible light

20. Chlorophyll • Neither type of chlorophyll absorbs green light • The green color of plants comes from the reflection of light’s green wavelengths by chlorophyll • 2 Main Types of Chlorophyll: • Chlorophyll a – absorbs mainly blue-violet and red regions • Chlorophyll b – absorbs mainly in blue and red regions

21. pigments

22. What are the reactants and products of photosynthesis?

23. Photosynthesis Reaction PHOTOSYNTHESIS:A process in which plants and cyanobacteria capture sunlight & convert water and carbon dioxide into oxygen and high energy carbohydrates- such as sugars (monosaccharides) and starches (polysaccharides) Reactants: carbon dioxide and water Products: oxygen and sugar (monosaccharide- glucose) 6CO2 + 6H20 C6H1206 + 6 O2 OR Carbon dioxide + water sugars + oxygen

24. P H O T O S Y N T H E S I S

25. Chloroplasts • The three main parts of chloroplasts needed for photosynthesis are the: • Grana-stacks of coin-shaped, membrane-enclosed compartments called thylakoids which contains chlorophyll • Thylakoids-inner membrane of the chloroplast • Stroma- the fluid that surrounds the grana inside a chloroplast

26. 3 Major Parts of a Chloroplast • Grana:(singular-granum) • Stack of thylakoid membranes • Increases light absorbing efficiency (surface area) • Contains chlorophyll • Thylakoid membranes: Inner membrane • Light-dependent reactions occur here • Embedded with chlorophyll & other pigments • Proteins in the thylakoid membrane organize chlorophyll and other pigments into clusters known as photosystems • Helps produce ATP • Stroma: dense, protein-rich gel like material surrounding Grana • Calvin Cycle (Light-Independent reaction) occurs here

27. What happens during the process of photosynthesis?

28. Process of Photosynthesis • 2 steps: 3 stages • Step 1 occurs in 2 Stages- • Light-Dependent Reaction (Light Reaction): • occurs in the thylakoid membrane – light energy is captured and transferred here by two groups of molecules called photosystems (photosystem I and photosystem II). Stage 1. Energy is captured from sunlight (pigments absorb light) • Water (H2O) taken into chloroplast • Oxygen (O2) is produced/released(comes from the water that gets broken down) Stage 2. Light energy is converted to chemical energy (temporarily stored as ATP& NADPH) • Energy (ATP & NADPH) is produced to power the 2ndstep = Calvin Cycle

29. Light-dependent reactions Photosystems II and I absorb energy from sunlight and transfer energy to the Calvin Cycle

30. What are some electron carriers that play a role in photosynthesis?

31. Electron carriers • A carrier molecule is a compound that can accept a pair of high-energy electrons and transfer them along with most of their energy to another molecule • This process is called electron transport and the electron carriers themselves are known as the electron transport chain

32. NADP+ is a carrier molecule that accepts and holds 2 high energy electrons along with a hydrogen ion (H+) form NADPH • NADP+ + 2 electrons (2 e-) + H+ = NADPH • NADPH carries these high energy electrons to chemical reactions elsewhere in the cell

33. Process of photosynthesis Step 2: • Stage 3 Calvin Cycle (Light-Independent Reaction) • Occurs in stroma and uses energy from the light-dependent reactions to make sugars • Carbon dioxide (CO2) is taken from atmosphere and brought into the chloroplast • CO2 is added to a cycle of chemical reactions to build larger molecules • A molecule of a simple sugar is formed (usually glucose, C6H12O6)

34. Light-independent reactions (Calvin cycle)

35. Compare/Contrast the light-dependent & light-independent reactions.

36. Summary of photosynthesis Stage 1 and 2 Stage 3 aka. Light Independent Reaction

37. Summary of photosynthesis Light-Dependent Reactions • Energy is captured from sunlight and energy is transferred to electrons that enter an electron transport chain (ETC) • Water molecules are broken down into H+ ions, electrons, and oxygen molecules. • Energized electrons provide energy for H+ ion transport and are added to NADP+ to form NADPH • The flow of H ions through a protein makes ATP • Products of this reaction are oxygen, NADPH and ATP • ATP and NADPH are used later to make sugars Light-Independent Reactions • Carbon dioxide enters the Calvin Cycle • ATP and NADPH are used from the light-dependent reaction • One high-energy 3-carbon molecule is made for every three molecules of carbon dioxide that enter the cycle • Two high-energy 3-carbon molecules are bonded together to make a sugar • Therefore, six molecules of CO2 must be added to make one 6-carbon sugar • The products are a 6-carbon sugar such as glucose, NADP+ and ADP • The NADP+ and ADP molecules return to the light-dependent reactions

38. How are gases & water exchanged in plants?

39. How are gases & water exchanged in plants? • Stoma (singular), stomata (plural) • Pore or opening found on plant leaves and stems used to control the exchange of gas (oxygen & carbon dioxide) • Guard cells- surround each stoma; regulate the rate of transpiration (evaporation of water) by opening and closing the stomata, help to maintain homeostasis

40. What 3 factors affect the rate of photosynthesis?

41. Factors Affecting the Rate of Photosynthesis • Light Intensity: • Increasing light can speed up photosynthesis • Extreme intensity can damage the chlorophyll • Availability of raw materials: (CO2, H2O) • A shortage of these can slow or even stop photosynthesis • Temperature: • 0-35ºC is ideal for enzymatic function

42. Rates of Photosynthesis vs. Regulating Factors • What happens as you continue to increase the light intensity that the plant receives? • What happens as the temperature of the environment the plant is in continues to increase?