BIO-1801 Lecture Notes - Lecture 10: Light-Independent Reactions, Oxidative Phosphorylation, Chlorophyll
14 May 2018
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Photosynthesis
I. Photosynthesis: the use of sunlight to manufacture carbohydrates.
II. Organisms that make organic molecules from inorganic ones are autotrophs self-feeders
A. Photoautotroph
a) Use Light as a source of energy
b) Green plants, algae, cyanobacteria.
III. Heterotrophs differet-feeders ust osue orgai oleules.
IV. Photosynthesis converts electromagnetic energy to chemical energy.
A. Requires sunlight, carbon dioxide, and water.
B. Produces oxygen as a by-product CO2 + H2O + light energy →→→ (CH2O)n + O2
C. Electron Transfer during photosynthesis: In carbon dioxide electrons are pulled closer; C is
reduced. In water electrons are pulled away; O is oxidized.
V. Chloroplasts: organelles in plants and algae that carry out photosynthesis. Endosymbiosis theory origin of this
organelle (DNA, Binary fission)
Chlorophyll: main pigment (green)
Mesophyll: The inner tissue of a leaf, containing many chloroplasts.
Mesophyll cells: Physial loatio i plat’s leaves. These ells have a lot of hloroplast i the.
Stomata: Tiny openings in plants that allow carbon dioxide to enter and oxygen to exit the leaf. The source of CO2
used in photosynthesis is the atmosphere.
VI. Photosynthesis consist of two sets of reactions
1. The light-dependent reactions produce O2, ATP, NADPH
a) Light dependent reactions occurs in the granum;
stacks of thylakoids.
b) Light, water, NADP+, and ADP enter the thylakoid.
c) Water is split in lumen of thylakoid to form O2 (gas)
d) Its electrons are excited by light energy, pump
protons to lumen.
e) High-energy electrons are transferred to the
electron carrier NADP+, forming NADPH
f) ATP is produced by chemiosmosis
(Oxidative phosphorylation)
2. The Calvin cycle reactions produce sugar from CO2.
a) Electrons (from NADPH) and ATP are used to reduce CO2
b) Calvin Cycle occurs in the stroma of the chloroplast.
VII. Photosynthetic pigments are located in the thylakoid membranes.
A. Most common pigment in thylakoids= Chlorophyll
a) Reflects green light, absorbs red and blue
b) Responsible for green color of plants and algae.
VIII. How do photosynthetic pigments Capture Light Energy?
A. Pigments: absorb some light energy and reflect other energies.
B. Pigments that are absorbed are transformed into energy
intermediates ATP and NADPH.
C. Visible light is the electromagnetic radiation that humans can see.
D. Each photon and wavelength has a specific amount of energy
a) Shorter wavelengths have more energy than longer wavelengths.
(ROYGBIV backwards) Blue wavelength has more energy than Red wavelength.
IX. There are two major classes of pigments in plants:
1. The chlorophylls (chlorophyll a and chlorophyll b)
a) Absorbs red and blue light
b) Reflect and transmit green light
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Document Summary
Photosynthesis: the use of sunlight to manufacture carbohydrates. Organisms that make organic molecules from inorganic ones are autotrophs (cid:894) (cid:862)self-feeders(cid:863)(cid:895: photoautotroph. Use light as a source of energy: green plants, algae, cyanobacteria. In water electrons are pulled away; o is oxidized. Chloroplasts: organelles in plants and algae that carry out photosynthesis. Endosymbiosis theory origin of this organelle (dna, binary fission) Mesophyll: the inner tissue of a leaf, containing many chloroplasts. These (cid:272)ells have a lot of (cid:272)hloroplast i(cid:374) the(cid:373). Stomata: tiny openings in plants that allow carbon dioxide to enter and oxygen to exit the leaf. The source of co2 used in photosynthesis is the atmosphere. Photosynthesis consist of two sets of reactions: the light-dependent reactions produce o2, atp, nadph. Light dependent reactions occurs in the granum; stacks of thylakoids. Light, water, nadp+, and adp enter the thylakoid: water is split in lumen of thylakoid to form o2 (gas)
