BLG 143 Study Guide - Final Guide: Photosynthetic Pigment, Chlorophyll, Isoprene
27 Apr 2018
School
Department
Course
Professor
10.2 Chlorophyll
Photosynthesis begins with sunlight striking chlorophyll.
Photosynthesis converts electromagnetic radiation, a form of light energy, into chemical
energy in the C-C and C-H bonds of sugar.
Light’s behaviour is both wave and particle like.
Wavelength distance between 2 successive wave crests; determines the type of
electromagnetic radiation
When a photon strikes an object, the photon may be absorbed, transmitted or reflected. A
pigment molecule absorbs particular wavelengths of light. Sunlight includes white light,
which is all the wavelengths visible to us.
There are 2 major classes of pigment in plant leaves:
1. Chlorophylls
• Designated chlorophyll a and b
• Absorb strongly blue and red regions in the visible spectrum
• Blue and red photons are the most effective at driving photosynthesis
• Most photosynthetic pigment
• Makes plant look green because they reflect and transmit green light, which
they don’t absorb
• Long tail made of isoprene subunits keeps molecule embedded in the
thylakoid membrane
• Head consisting of large ring structure with a magnesium atom in the middle
where the light is absorbed
2. Carotenoids
• Absorb in the blue and green parts of the visible spectrum
• Appear yellow, orange or red
• Absorb wavelengths of light that’re not absorbed by chlorophyll
• Extend the range of wavelengths that can drive photosynthesis
• Quench free radicals by accepting or stabilizing unpaired electrons
• Protect chlorophyll molecules from harm
• When absent, chlorophyll molecules are destroyed and photosynthesis stops,
starvation and death follow
Chlorophyll molecules work together in groups, forming a complex called a photosystem.
1. The Antenna Complex
• When a red or blue photon strikes a pigment molecules in this complex,
energy is absorbed and an electron is excited in response
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Photosynthesis converts electromagnetic radiation, a form of light energy, into chemical energy in the c-c and c-h bonds of sugar. Light"s behaviour is both wave and particle like. Wavelength distance between 2 successive wave crests; determines the type of electromagnetic radiation. When a photon strikes an object, the photon may be absorbed, transmitted or reflected. A pigment molecule absorbs particular wavelengths of light. Sunlight includes white light, which is all the wavelengths visible to us. There are two types of reaction centres: photosystem i and photosystem ii. Photosynthesis is moderate at red light and at a far red light, and is greatly enhanced when red and far red light are combined. Ii reacts with a different reaction centre, i. The enhancement effect occurs because photosynthesis is much more efficient when both photosystems operate together. Led to recognition of two separate photosystems that work in concept, one with max 680nm absorption and the other with 700nm.
