66847 - Photobiology

Learning outcomes

The course will provide an  interdisciplinary basis for the study of photobiological processes at the molecular level, with special emphasis on photosynthesis and photoreception.

Course contents

To profitably follow the course the student should have some background in biochemistry, chemical physics, and photochemistry.

It is not mandatory to attend all the lessons of the course.

The course includes an introductory part in which the basic notions of chemical physics and photochemistry, specifically needed to analyze the photobiological systems covered by the course, are summarized; the spectral properties of the main chromophores associated with photoactive protein complexes are also discussed. Subsequently the crystallographic structures of the pigment-protein complexes which catalyze the primary events of photosynthesis, vision, and other photobiological processes (photoreception, enzymatic activity of photolyase) are reviewed. The structures are put in relation with the molecular mechanisms which govern the biological function and the different methods used to characterize photobiological systems at the molecular scale are discussed.

 

Detailed Course contents.

1. Basic notions of photophysics and photochemistry

1.1 Electronic transitions. The Franck-Condon principle. Quantum yield of photophysical and phochemical processes

1.2 Excitation energy transfer: Foerster and Dexter mechanisms.

1.3 Intraprotein electron transfer mechanisms: Marcus theory and quantum-mechanical models.

2. Spectal properties of chlorophylls, carotenoids, phycobilins.

3. Photosynthesis: general concepts.

3.1 The organization of photosynthetic membranes in oxygenic and anoxygenic systems

3.2 The electron transfer chains and the chemiosmotic transduction of light energy

4. Photosynthetic antenna systems: crystallographic structures and energy transfer mechanisms

4.1 The LH1 and LH2 complexes of red bacteria and their supramolecular organization

4.2 Chlorosomes

4.3 Peridinin- chlorophyll antenna systems in dinoflagellates

4.4 The LHC 2 complexes and the regulation of energy transfer in oxygenic photosynthesis

5. The photosynthetic reaction center: crystallographic structure and mechanisms of electron transfer

5.1 The bacterial reaction center as as a model system of Q-type reaction centers

5.2 the photosystems of oxygenic photosynthesis: PS1 and PS2

5.3 The OEC complex

5.4 Charge separation and conformational dynamics of the reaction center

6. Bacteriorhodopsin: structure and photocycle

7. Visual rhodopsin and the primary processes of vision

8. Plant photoreceptors: phytochromes and cryptochromes

9. Photolyase: structure and catalytic mechanism

Readings/Bibliography

The teacher will provide the power point presentations used during the course, as well as review and research papers in order to deepen specific topics.

 

Teaching methods

The course consists of lectures.

Assessment methods

The examination aims to ascertain the attainment of the following, main didactic objectives: (a) the knowledge of the chemico-physical bases of the primary, photobiological  processes presented in the lectures; (b) the knowledge of the biological context (cytological, physiological) which characterizes the handled photobiological processes; (c) the ability of analyzing and discussing chemico-physical results taken from the scientific literature in the photobiological field. The exam consists in the presentation and discussion of a first argument chosen by the candidate, followed by a colloquium on arguments treated during the course.

Teaching tools

Personal computer, digital projector, power point presentations, blackboard.

Office hours

See the website of Giovanni Venturoli