October 10 2012
Chapter 1: Life and Light
- Uses light for both energy & info
- Eyespot: light sensor (determines whether to move toward or away from light, chloroplasts
harvest light and use it as energy ex: photosynthesis)
- One type is called Chlamydomanas Reinhardtii
The Sun – Reason why there’s life on Earth. Sun produces electromagnetic radiation which gets
absorbed by pigments in molecules in organisms.
Length of wave determines kind of electromagnetic radiation
400 to 700nm is visible light. Short = high energy, long = low
LIGHT: ER that humans can detect with their eyes
A Photon is a wave of discrete particles
Wavelength – distance between two peaks
Light energy must be absorbed by molecules called pigments. NOT reflected or transmitted.
Pigments absorb light energy
The light reflects, absorbs or transmits depending on the pigment.
PIGMENT: a conjugated system with alternating single and double bonds which enables electrons to
become delocalized and therefore can interact more freely with photons.
Different pigments transmit different waves of life
An electron is promoted to a higher/lower energy state when photos are absorbed
The difference between the ground state and higher energy state equals the amount of energy the
photon supplies that ends up being absorbed
The colour seen is either transmitted or absorbed therefore the photon does not supply that amount of
energy that is being absorbed.
The smaller the wavelength the more energy therefore the energy state will be farther away. Halobacterium captures light with the protein retinol which is embedded in the transmembrane helixes
in the seven cylinders inside plasma. It changes shape if transport protons from