Photosynthesis. The Sun powers life. capture about 5% of the Sun s energy and, through the process of, provide energy to.

Transcription

1 Photosynthesis The Sun powers life. capture about 5% of the Sun s energy and, through the process of, provide energy to.

2 Photosynthesis is carried out by : These organisms all contain the pigment. There are several types of found in photosynthetic organisms; are 2. is the in all organisms.

3

4 is composed of a ring attached to a. Delocalized electrons in the in the ring and begin the photosynthetic process

5 Cyanobacteria Cyanobacteria live in many different environments including. On rocks, cyanobacteria associate with. Probably the first organisms to use from water and carbon dioxide.

6 First cells to produce, they paved the way for on Earth. Cyanobacteria are closely related to the. The proposes that an ancestor of cyanobacteria was, an association that was mutually beneficial. (Evidence - like mitochondria, have a, contain their own, and the are able to.)

7 Eukaryotic Autotrophs Algae, some protists, and plant cells contain chlorophyll within the

8 Chloroplasts. The membranes enclose a semiliquid material called. In the, membrane bound sacs called stack to form. (.) are joined by unstacked thylakoids called. Photosynthesis occurs partly within and partly within the. This overall structure membrane and, therefore.

9 Light Energy The reactions of photosynthesis can be broken down into 3 parts Stage 1: Stage 2: Stage 3:.

10 Stage 1 and 2 are directly energized, and are called. The light energy is eventually transferred to in stage 3, known as which takes place in the via the Used to be called the - no more

11

12 Electromagnetic spectrum

13 Photosynthetic pigments, called (embedded in ) absorb photons of particular wavelengths and, through the, transfer their energy to.

14 Engelmann s experiment

15 The of photosynthesis (wavelength vs rate) matches nicely a spectrophotometers results of an.

16 Chlorophyll and Accessory Pigments absorb photons with energies in the. is the pigment that can transfer the reactions. acts as an, absorbing photons that.

17 Other accessory pigmnets: (ex. β-carotene) absorb light energy in the range from 400 nm to 500 nm - type of carotenoid that absorb light, which would otherwise. (appear yellow) Both are found in the. (red, violet, and blue) are primarily located in and protect against light damage.

18 When the absorption spectra of all are combined the range covers (400 nm to 700 nm) This light is called

19 The Light Reactions Photosynthesis begins when photons strike a photosynthetic membrane. Three parts:

20 Photoexcitation Electrons in chlorophyll are in their (lowest energy) When a photon of light strikes them, the electron level (excitation). The excited electron is. Energy must be (heat and light - called ).

21 In a plant however, the is captured by a special molecule called the in a redox reaction.

22 Photosystems In a, light is absorbed by a. Consists of an and a. The antenna complex is composed of set in a and embedded in the.

23 Antenna pigments energy until it reaches at the reaction centre. An electron of this chlorophyll gets excited, and is transferred to a.

24 2 types of photosystems called is called P700 because its absorption spectrum peaks at is called P680 because it is best at absorbing photons

25 Noncyclic Electron Flow and Chemiosmosis Plants use to produce. Known as 1. A photon strikes and excites an electron of chlorophyll. 2. Electron is captured by a called.

26 3. Electron is transferred to (PQ) 4. Electron transferred to an. This process occurs twice. 5. A, splits water. The e- replace the electrons. O2 leaves as waste, and the H+ remain adding to the H+ gradient "Q cycle"

27 6. As e- pass through the, pass from the into the for each pair of electrons 7. The e- move through, Pc, and replace the that were lost by.

28 8. The e- from pass through containing (Fd). 9. Then e- move to the enzyme. The from the then reduce.

29 10. H+ collect in the forming an 11. H+ move through the into the, and (photophosphorylation). Requires per ATP.

30

31 Cyclic Electron Flow Sometimes e- take pathway that uses only. 1. A photon ejects an electron from of photosystem I. 2. The e- is passed to, and then goes through the, the, and back to. A proton gradient forms. However no is made. Without, the reactions of cannot occur

32 Rates of are regulated by the NADPH : NADP+ ratio When the ratio is, (high light) because very little will be available.

33 Part 2 - The Calvin Cycle Takes place in the. Similar to the in that some of the starting material is regenerated. The Calvin cycle can be divided into three phases:

34 Phase 1: Carbon Fixation is added to an already existing 5- carbon molecule,, RuBP, to form two 3-carbon molecules called. This happens times 3 CO2 react with 3 RuBP to produce six molecules of PGA Since the first compound contains, the Calvin cycle is also known as. Most plants are C3 plants ribulose bisphosphate carboxylase/oxygenase

35 Phase 2: Reduction Reactions The six molecules of PGA by an ATP to form six molecules of A pair of electrons from each of reduces six molecules of 1,3- BPG to six molecules. (Think reverse of ). One molecule of as a final product.

36 Phase 3: RuBP Regeneration Remaining 5 G3P are rearranged to form. are used in the process. RuBP may now fix more. G3P molecules will synthesize larger sugars of the Calvin cycle will fix enough to produce the equivalent of

37 Overall: You complete the case study on the Discovering Metabolic Pathways on pg

38 Complete the Alternative Mechanisms of Carbon Fixation Worksheet

39 You know pigments work together in a photosystem to provide the energy necessary for the light reactions. Chromatography is a technique used in biology to isolate molecules in their pure form. Two common types of chromatography are column chromatography and paper chromatography. Column chromatography separates molecules based on their size and/or their electrical charge.

40 In this investigation, you will use paper chromatography to separate the photosynthetic pigments in a leaf extract. Paper chromatography separates molecules based on their different solubilities in a solvent. Molecules that are very soluble will stay dissolved in the solvent and travel a greater distance along the chromatography paper. Molecules that are insoluble will stay near the beginning. Once the molecules are separated on the paper, the paper can be cut and each pigment can be redissolved in a solvent. The isolated photosynthetic pigments can then be studied further to determine their unique characteristics.