Photosynthesis. Biol 1107L Spring 2015 Japhia Jacobo

Transcription

1 Photosynthesis Biol 1107L Spring 2015 Japhia Jacobo

2 Overview: The Process That Feeds the Biosphere Photosynthesis is the process that converts solar energy into chemical energy

3 Autotrophs sustain themselves without eating anything derived from other organisms Autotrophs are producers - producing organic molecules from CO 2 and other inorganic molecules

4 Photosynthesis occurs in plants, algae, certain other protists, and some prokaryotes These organisms feed not only themselves but also most of the living world

5 Chloroplasts are structurally similar to photosynthetic bacteria The structural organization of these cells allows for the chemical reactions of photosynthesis

6 Chloroplasts: The Sites of Photosynthesis in Plants Leaves are the major locations of photosynthesis Their green color is from chlorophyll, the green pigment within chloroplasts

7 Tracking Atoms Through Photosynthesis Photosynthesis is a complex series of reactions that can be summarized as the following equation: 6 CO H 2 O + Light energy C 6 H 12 O O H 2 O

8 Photosynthesis as a Redox Process Photosynthesis is a redox process in which H 2 O is oxidized and CO 2 is reduced Photosynthesis is an endergonic process; the energy boost is provided by light

9 Figure 10.UN01 becomes reduced Energy 6 CO 2 6 H 2 O C 6 H 12 O 6 6 O 2 becomes oxidized

10 The Two Stages of Photosynthesis: A Preview Photosynthesis consists of the light reactions (the photo part) and Calvin cycle (the synthesis part) The light reactions Split H 2 O Release O 2 Reduce NADP + to NADPH Generate ATP from ADP by photophosphorylation

11 The Calvin cycle forms sugar from CO 2, using ATP and NADPH The Calvin cycle begins with carbon fixation, incorporating CO 2 into organic molecules

12 The Nature of Sunlight Light is a form of electromagnetic energy/radiation Light travels in rhythmic waves Wavelength is the distance between crests of waves Wavelength determines the type of electromagnetic energy

13 Figure m 10 5 nm 10 3 nm 1 nm 10 3 nm 10 6 nm (10 9 nm) 10 3 m Gamma rays X-rays UV Infrared Microwaves Radio waves Visible light nm Shorter wavelength Higher energy Longer wavelength Lower energy

14 Photosynthetic Pigments: The Light Receptors Pigments are substances that absorb visible light Different pigments absorb different wavelengths Wavelengths that are not absorbed are reflected or transmitted Leaves appear green because chlorophyll reflects and transmits green light

15 Pigments Green plant photosynthesis carotenoids chlorophyll chlorophyll a - main pigment chlorophyll b - accessory pigment

16 Pigments Chlorophyll a is the main photosynthetic pigment Accessory pigments, such as chlorophyll b, broaden the spectrum used for photosynthesis Accessory pigments called carotenoids absorb excessive light that would damage chlorophyll

17 Absorption Spectra Carotenoids can absorb photons with a wide range of energies, however they are not as efficient at transferring energy as chlorophyll. They assist in photosynthesis by capturing energy from light composed of wavelengths that are not efficiently absorbed by chlorophyll.

18 Absorption Spectra Fall colors are produced by carotenoids and other accessory pigments. During the spring and summer, chlorophyll masks the presence of the carotenoids and the other pigments. In the fall, leaves stop making chlorophyll The remaining carotenoids reflect the yellow and orange that the chlorophyll and other pigments do not absorb.

19 What is Chromatography? Chromatography is a technique for separating mixtures into their components in order to analyze, identify, purify, and/or quantify the mixture or components. Mixture Separate Components Analyze Identify Purify Quantify

20 Definition of Chromatography Simplified Definition: Chromatography separates the components of a mixture by their distinctive attraction to the mobile phase and the stationary phase. Explanation: Compound is placed on stationary phase Mobile phase passes through the stationary phase Mobile phase solubilizes the components Mobile phase carries the individual components a certain distance through the stationary phase, depending on their attraction to both of the phases

21 Illustration of Chromatography Stationary Phase Separation Mixture Mobile Phase Components Components Affinity to Stationary Phase Affinity to Mobile Phase Blue Insoluble in Mobile Phase Black Red Yellow

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23 Use exercise 3 and 4 to identify the pigments in the plant leaf Two methods of identification chromatography and wavelength absorption Lab report will include if the results from these methods corroborate or contradict each other