Phytochromes and Etiolation
Bio 1400
Biological Inquiry
What are photoreceptors?
• The retina of vertebrates contains two types
of photoreceptor cells: rods and cones
– ww.retinalmicroscopy.com/photoreceptors.html
Photoreceptors receive light energy
from outside the cell
CELL
WALL
CYTOPLASM
Light energy chemical
and electrical signals
Cell response: change
in gene expression
DNA  RNA protein
Phytochrome structure in plants
How do phytochromes work in plants?
Electromagnetic Radiation from Sun
far-red 700-800nm
Absorption spectra of phytochrome forms
660nm
730nm
SIGNAL TRANSDUCTION:
Process that allows conversion of light energy
chemical and electrical energy  gene expression
Changes in wavelength of light are
detected by phytochromes
http://www.bio.miami.edu/dana/226/226F08_21.html
Watch the animation for more details
• http://highered.mheducation.com/sites/9834
092339/student_view0/chapter41/animation_
-_phytochrome_signaling.html
On your own:
• Perform an internet search to investigate the
function of vertebrate photoreceptors.
• How are these proteins similar to
photoreceptors in plants? How are they
different?
• Bring your findings for discussion in class on
Tuesday, 9-16-14