Photosystem organization

Question 1

What do experiments on photosynthesis show?

Answer 1

• They show that the output of photosynthesis increases linearly at low-light intensities
• They also show that photosynthesis doesn’t increase further (saturates) at high-intensity light

Question 2

Why would saturation in photosynthesis occur?

Answer 2

-It will occur bc all the light-absorbing capacity of the plant is in use

Question 3

What does production of one O2 molecule require?

Answer 3

• 2,500 chlorophyll molecules
• Which led to the idea that light is absorbed by clusters of chlorophyll & accessory pigment molecules & that each pigment transfers its excitation energy to a single molecule w/ a lower energy level

Question 4

What is a photosystem made up of?

Answer 4

• It is a network of chlorophyll-a molecules, accessory pigments, & associated proteins held within a protein matrix on the surface of the photosynthetic membrane
• Also consists of 2 closely linked components

Question 5

How does a Photosystem work?

Answer 5

• It channels the excitation energy gathered by any of its pigment molecules to a specific molecule=the reaction center of the chlorophyll
• This molecule then passes the energy out of the photosystem as excited electrons that are put to work as ATP & organic molecules

Question 6

What are the 2 closely linked components of the photosystem?

Answer 6

• The Antenna Complex

- The Reaction Center

Question 7

What is the Antenna Complex?

Answer 7

• AKA Light harvesting complex
• They consist of hella pigment molecules that capture photons from sunlight & channels them to the reaction center of the chlorophylls

Question 8

What is the structure of the Antenna Complex?

Answer 8

• Consists of a web of chlorophyll molecules linked together & help tightly in the thylakoid membrane by a matrix of proteins
• The matrix of proteins holds individual pigment molecules in orientations that are optimal for energy transfer

Question 9

What is the Reaction Center?

Answer 9

• It is a transmembrane protein-pigment complex
• It has one or more chlorophyll-a molecules in the matrix of a protein=passes excited electrons & their energies out of the photosystem

Question 10

What is the difference between the Antenna Complex & the Reaction Center?

Answer 10

-The Antenna complex is only for the excited electron’s energy vs the Reaction Center is for both the excited electron itself & its energy