1.4 DETECTING AND AMPLIFYING AN ENVIRONMENTAL STIMULUS Flashcards
Where are photoreceptor protein systems present?
Across the three domains
What are the three domains?
Bacteria, Archaea, Eukaryota
In which domain are plants, animals and fungi found?
Eukaryota
How can light energy be used to generate ATP?
It can be used to generate a proton gradient to drive ATP synthase
What molecule absorbs light energy in archaea?
Bacteriorhodopsin
How does bacteriorhodopsin absorb light energy?
Its prosthetic group, retinal, absorbs energy from photons
How does the light energy absorbed by bacteriorhodopsin generate a proton gradient?
The energy is used to pump protons through the bacteriorhodopsin so that a proton gradient is created across the membrane
What molecule absorbs light energy in plants?
Photosynthetic pigments within the chloroplast absorb energy from photons
How does the light energy absorbed in the chloroplast generate a proton gradient?
It drives an electron flow that pumps hydrogen ions across the thylakoid membrane of the chloroplast
What is the thylakoid membrane?
A compartment inside a chloroplast
How does the proton gradient generate ATP?
It results in the diffusion of hydrogen ions back across the membrane, driving ATP synthase
What is retinal?
A light-sensitive molecule
What is retinal combined with (in animals)?
It is combined with membrane protein opsin
What amplifies light signals (in animals)?
A cascade of proteins
What are the two types of cell found in the retina?
Rod cells and cone cells
