Unit 3 Metabolism – Energy Production & Use

1. Unit 3Metabolism – Energy Production & Use Chapter 6 – Photosynthesis Chapter 7 – Cellular Respiration

3. The Big Picture Formula Photosynthesis Cellular Respiration Carbohydrates + Oxygen = Energy + Carbon dioxide + Water Sunlight + Water + Carbon dioxide = Carbohydrates + Oxygen

4. 6CO2 + 6H20 = C6H12O6 + 6O2 Done by AUTOTROPHS using the sun’s energy 6O2 + C6H12O6 = 6CO2 + 6H20 Used by HETEROTROPHS to use energy from the sun trapped in molecules Another way – the formula:

5. Biochemical Pathway • A series of complex chemical reactions linked together to accomplish a task vital to the ecosystem • Like PHOTOSYNTHESIS • Like CELLULAR RESPIRATION

6. Unit 3Metabolism – Energy Production & Use Chapter 6 – Photosynthesis 6-1 The Light Reactions pp113-8

7. 2 Stages of Photosynthesis Light Dependent Reactions Light Independent Reactions Energy-bearing molecules produced in light dependent reactions used – ATP and NADPH Carbon dioxide and water assembled into larger energy-storage molecule – glucose Also formed are ADP, P, and NADP+ which are used again in the light dependent reactions Otherwise called the Calvin Cycle • Photons – units of energy from the sun – are used • The energy from the photons splits water creating electrons and protons from the hydrogen atoms in water • Electrons and protons are used to create electrical gradients - positive and negative charges – on opposing sides of a membrane • Energy-bearing molecules are made for the next stage • These are ATP and NADPH

8. Light Dependent Reactions – occur in chloroplasts

9. Found in cytoplasm of plant cells

10. Where are the chloroplasts located?In the mesophyll region - center

11. Parts of the chloroplast: • Outer membrane • Inner membrane • Stroma • Thylakoid • Thylakoid membrane • Granum

12. A little more about light:The electromagnetic spectrum – all forms of energy that travels through space by waves.The sun produces all forms and we receive them here on Earth – but only SEE a few

13. Visible light – a VERY small part of the electromagnetic spectrum

14. How do we interpret light?

16. What about plants?

17. Pigments inside plants on the thylakoid membranes: Chlorophyll a & b Carotenoids Make plants look yellow, orange or red Reflect yellow, orange and red light Absorb green and blue light • Make plants look green • Reflect green light • Absorb all other colors of visible light

18. So why doleaveschangecolor?Well, actually, they really don’t!Chlorophyll needs the strong light of summer to be active and actively made by plants. Gradually, there is less of it made as summer light weakens. When sun lightbecomes weaker in Fall, the other carotenoids that have been in leaves all summer become muchmore visible – and wethink the leaves have changed color!

19. Some plants have stunning color all the time, and it is due to the pigments they have and what light is reflected by the pigments

20. Sunlight travels through the outer and inner membranes, through the stroma, strikes pigments (chlorophyll & carotenoids on the thylakoid membrane). On this membranethe light-dependent reactions will take place.

21. LIGHT DEPENDENT REACTIONS

22. LIGHT DEPENDENT REACTIONS • On the thylakoid membrane chlorophyll molecules absorb sunlight • There are several hundred chlorophyll molecules for every single photosystem protein • Photosystem II – the first protein to begin the reactions and starts the whole process • Inside the thylakoid is a watery gel • The absorbed energy from the sun is used to split water molecules with an enzyme’s help • THIS IS WHY PLANTS MUST HAVE WATER!!!!

23. LIGHT DEPENDENT REACTIONS • When water molecules are split, 2 electrons and 2 protons are made, and one oxygen atom. • 2 H2O split = 4 electrons, 4 protons, 1 O2 • THIS IS HOW PLANTS MAKE OXYGEN GAS!!! • Several electron receptor proteins in the thylakoid membrane help the electrons that are excited by the solar energy move to the next protein, called PhotosystemI • Photosystem I also absorbs solar photons, to re-energize the electrons passing through

24. LIGHT DEPENDENT REACTIONS • Passing electrons along theELECTRON TRANSPORT CHAINon the thylakoid membrane causes protons from hydrogen to remain inside the thylakoid membranes • Electrons keep on entering the CHAIN as water is split and sunlight is absorbed in PSII and PSI • Electrons build up on the thylakoid membrane • This creates an electrical potential – a concentration gradient of electrical charge • Negative on the outside of the thylakoid membrane, positive inside thylakoid membrane

26. So, what are we going to do with all those electrons on the thylakoid membrane and protons in the gel inside the thylakoid?CHEMIOSMOSIS

27. What’s CHEMIOSMOSIS?Moving protons across a membrane to a lower concentration area and using this movement to make energy-bearing molecules:NADPH and ATP

28. What are NADPH and NADP+ ? • NADP+ is Nicotinamide adenine dinucleotide phosphate • NADPH is the same, with “oxidase” at the end • What do they do? • They’re both great at transferring electrons across a membrane! • What parts of the molecular structure do you recognize? • What parts of the name do you recognize?

29. What are ATP and ADP? • ATP is Adenosine triphosphate • ADP is Adenosine diphosphate • What do they do? • They hold and transfer energy in living cells • What parts of the molecular structure do you recognize? • What parts of the name do you recognize? • ATP was part of the squirrel packet in the nucleic acids section

31. LIGHT DEPENDENT REACTIONS • Electrons from the electron transport chain bond to NADP (an electron acceptor) in the stroma to form NADPH+ • An enzyme, ATP SYNTHASE pumps the hydrogen protons from inside the thylakoid to the outside where there are far less protons, generating ATP • NADPH+ and ATP – are energy currency and very important for the next stage in photosynthesis:LIGHT INDEPENDENT REACTIONS https://www.youtube.com/watch?v=joZ1EsA5_NY

32. Unit 3Metabolism – Energy Production & Use Chapter 6 – Photosynthesis 6-2 The Light Independent Reactions – the CALVIN CYCLE pp120-4