Biology and Sustainability by the Numbers


Course given on fall semester by Ron Milo, teaching fellows: Lior Greenspoon and Sam Lovat

Mondays 11:15-13:00 @ Wolfson auditorium

Course email (to send suggestions, errors, insights...):

Main reading resource: "Cell Biology by the Numbers" book

Vignettes that reveal how numbers serve as a sixth sense in understanding so much about the world - from the logic of cells in our body to our impact on Nature

Course outline

Subject 1: Quantitative reasoning in molecular and cell biology (YouTube)

Exercise 1 - due by 18/12/2023


Subject 2: Size and mass (YouTube)

Exercise 2 - due by 1/1/2024


Subject 3 : Concentration and absolute numbers (YouTube)

Exercise 3 - due by 15/01/2024


Subject 4: Rates (Youtube)

Excercise 4 - due by 29/01/2024


Subject 5: Energy, food and humanity (Youtube)

Exercise 5 - due by 05/02/2024


Subject 6: Mutations and evolution (YouTube)


Guest lecture: The Number of Human and Bacterial Cells in the Body (YouTube)


Guest lecture: The Global Biomass of Mammals (YouTube)


Course description and syllabus:

Over the past decades, biology and environmental studies have evolved rapidly from descriptive, qualitative disciplines to more analytical, data-driven and quantitative fields. Our ability to collect numbers that describe the most basic processes around us has increased significantly, and simple calculations based on these data can provide important insights and enrich our scientific intuition.

This course is aimed at exposing students to the practice of making back of the envelope calculations (so called Fermi problems) with key numbers from the fields of biology and sustainability, and its useful applications in research. We will learn how to identify the major factors that determine the order of magnitude of the results, when to allow simplification, how to calculate them efficiently, and how to avoid common pitfalls.

The course is composed of weekly lectures on different aspects of quantitative cell biology and sustainability through many examples of basic (yet often surprising) questions:

-Size and geometry (e.g. What is larger, mRNA or the protein it codes for? How many cells are there in a human?)

- Concentrations and absolute numbers (e.g. What is the elemental and macromolecular composition of a cell? How many virions result from a single viral infection?)

- Energies and Forces (e.g. What is the power consumption of a cell? How much does protein synthesis take out of the entire energy budget of a cell?)

- Rates and durations (e.g. How long does it take cells to copy their genomes? What is faster, transcription or translation? What are the time scales for diffusion in cells?)

- Information and errors (e.g. What is the mutation rate during genome replication? What is the error rate in transcription and translation?)

The last few meetings of the course will be dedicated to presentations of student calculations as a final assignment.

Accompanying texts:

Course book is freely available at: bionumbers

Specific reading material will be given during the course.

* Those who did not take a molecular biology course should read the first few chapters of "Essential Cell Biology", Alberts et al, Garland Science

Other recommended readings (none compulsory, all for enrichment and fun):


Attendance and active participation is required.

50% - Weekly assignments

50% - Final assignment (presentation + written vignette)

Interesting links:

BioNumbers Database

BioNumber of the month

Key numbers in cell biology (with reference links)

Physical Biology of the cell at Caltech - Rob Phillips group