91243 - Photobiophysics and Photobiology

Learning outcomes

At the end of the course the student has acquired 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 deals with the primary events of photosynthesis and the involved pigment-protein complexes, photoreception (visual and non visual) and other non-photosynthetic photobiological processes.

When needed to analyze the photobiological systems and mechanisms covered by the course, the relevant specific notions of photophysics and photochemistry will be recalled and deepened. As a general approach, the photobiological processes examined will be first presented within their biological context at the cellular and physiological level. Subsequently, the crystallographic structures of the pigment-protein complexes which catalyze the primary events of photosynthesis, photoreception and the other considered photobiological processes (e.g. enzymatic activity of photolyase) will be reviewed. Structures will be put in relation with the molecular mechanisms which govern the biological function and the different experimental approaches used to clarify structure-function relationship at the molecular scale will be discussed.

Detailed course contents

1. Photosynthesis: general concepts and thermodynamical aspects.

1.1 The organization of photosynthetic membranes in oxygenic and anoxygenic systems

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

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

2.1 Spectral properties of chlorophylls, carotenoids, phycobilins.

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

2.3 Chlorosomes

2.4 Peridinin- chlorophyll antenna systems in dinoflagellates

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

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

3.1 The reaction center of purple bacteria as a model system of Q-type reaction centers

3.2 The photosystems of oxygenic photosynthesis: PS1 and PS2

3.3 The OEC complex

3.4 Charge separation and conformational dynamics of the reaction center

4. Protective and adaptive mechanisms of photosynthesis

4.1 Photoinhibition and photoprotection

4.2 Cellular mechanisms and strategies to hinder photoinhibition damages

5. Bacteriorhodopsins

5.1 Structure

5.2 Photocycle and mechanism of proton pumping

6. Opsins

6.1 Visual rhodopsin and primary processes of vision

6.2 Melanopsins and circadian rhythms

7. Non-visual photoreceptors

7. Phytochromes

7.2 Cryptochromes

7.3 Phototropins

8. Photoinduced repair processes in the cell: photolyase, structure and catalytic mechanism

Readings/Bibliography

The teacher will provide the PowerPoint 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. During the lectures the teacher will present the contents using PowerPoint presentations that will be provided to the students. Questions during lectures and discussion of the presented topics will be encouraged. Attendance of lectures is not mandatory, but it is strongly recommended, as the contents will be presented in details.

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, PowerPoint presentations, blackboard.

Office hours

See the website of Marco Malferrari