Molecular Biology B


The main objective of the course of Molecular Biology B is to present the macromolecules that are essential to life processes with focus on the processes of replication, transcription and translation.

Students will be exposed to a generalist introduction of the different macromolecules that ensure viability of a cell (bacterium or eukaryotic cell) with a special attention to the molecular processes that allow the transmission and interpretation of hereditary information. The different processes will be detailed so that students are able to identify several components that perform different functions in each molecular process.

After attending this course students should be able to:

  • Identify the different components that are found in different cell types.
  • Describe how the DNA molecule was identified as a determinant for hereditary information.
  • Identify the chemical composition of the DNA molecule, its structure and its organization within a cell.
  • Describe the DNA replication process, the mechanisms that ensure the reliability of this process and how the different elements can be used in the laboratory.
  • Describe the process by which the information encoded in the DNA molecule is converted into mRNA (transcription) and protein (translation).
  • Identify mechanisms that ensure the regulation of gene expression.

General characterization





Responsible teacher

José Paulo Nunes de Sousa Sampaio, Sérgio Joaquim Raposo Filipe


Weekly - 4

Total - 59

Teaching language



The frequency of Molecular Biology B practical classes is compulsory.

 In these practical classes, students will be able to perform tasks, routinely carried out in a Molecular Biology laboratory. Through the successful implementation of each experimental protocol, and the questioning about the importance of each performed task, students should be able to integrate the concepts taught in the theoretical classes and to interpret the experimental results obtained.


Molecular Biology of the Cell; B. Alberts, A. Johnson, J. Lewis, D. Morgan, M. Raff, K. Roberts, P. Walter; 6th edition (2015). Garland Science, Taylor & Francis Group, New York.

Biologia Celular e Molecular; C. Azevedo, C. E. Sunkel; 5th edition (2012). Lidel, Porto.

Slides and documents that will presented in the theoretical classes and in the practical classes by lecturers.

Webpages of associations, such as the American Society for Microbiology or the Howard Hughes Medical Institute, with content associated with topics taught in class.

Teaching method

Theoretical classes with slides for presentation of contents, solving and/or discussing problems.

Practical classes to execute experimental protocols, analysis and interpretation of experimental results and oral presentations.

Access to contents in the Moodle page with exercises and presentations about the contents that are taught.

Evaluation method

The evaluation will have two components:

- a theoretical-practical evaluation with two written tests with questions about the contents taught in the theoretical classes and practical classes (75% of the final classification) and calculated to one decimal place.

- a component of laboratory evaluation, evaluated through a process of continuous evaluation of the student in the laboratory (25% of the final classification, ie 5/20 points). This assessment, with a classification carried out to one decimal place at all times of assessment, will be carried out through the presentation, at the beginning of all practical classes, a graphical abstract of the procedures that will be performed by students in these classes (1/20 points) and the presentation of a film, with a maximum duration of 4 min, presenting protocols 2 and 3 and discussing the results obtained (4/20 points).

Subject matter

The course program includes the following topics:

  1. Molecular components of cells and their functions.
  2. Experiments that demonstrated how DNA is responsible for heredity.
  3. Structure and chemical composition of different nucleic acids found within a cell.
  4. Characterization of the DNA present in a cell (composition, organization and packaging).
  5. Mechanisms used for the high-fidelity propagation of DNA (replication).
  6. DNA modification and mutagenesis processes.
  7. Mechanisms of recombination and repair of the DNA molecule.
  8. Processes that allow cells to read information encoded their genome: (1) from DNA to RNA (transcription); (2) RNA for protein (translation).
  9. Control of gene expression.

The protocols performed in the laboratory include:

  1. Propagation of bacterial cells in liquid culture media.
  2. Isolation, purification and quantification of nucleic acids.
  3. Quantification and purity analysis of a DNA sample by UV spectrophotometry.
  4. Enzymatic hydrolysis of plasmid DNA and analysis of the resulting fragments by agarose gel electrophoresis.
  5. Amplification of DNA fragments by PCR.
  6. Regulation of genetic expression: evaluation of the activation of the Lac operon.