Chapter 1: Light and Life
What is light?
- The visible region of the electromagnetic spectrum, the only part we can see (380-
- Is decribed according to wavelength, but behave as massless particles called
photons (energy packet).
- Light interacts with matter by: reflection, transmission, or absorbtion (with
respect to an object).
- Pigments are molecules which mediate the amount of light energy absorbed by
an object (varies).
-> Have a molecular structure that allows them to absorb light.
-> Assorted by different wavelengths.
-> Pigments are made up of a series of covalently bonded (single and double)
carbon atoms (conjugated system).
Light & Life
- Photosynthesis: Sun -> Cellular Respiration -> Energy
- Photoreceptor (light sensor): a light sensitive protein involved in sensing and
responding to light (ex; rhodopsin, bacteria rhodopsin, phytochrome).
-> mediate light responses, and responses to light and dark.
- Retinals is a pigment molecule which change shape when exposed to light
yeilding a reaction.
- Chlamydomonas eyespot (contains rhodpsin). Senses light, and moves to it to
maximize E uptake.
- Phototaxis : the direction of movement toward or away from a light stimulus.
-> Positive : mo