The key difference between population doubling and passage number relies on the role they play in cell culture. Population doubling is the time taken for the cells in a culture medium to double its cell population while passage number refers to the number of times the cell culture has been doubled from its primary culture.
Population doubling and passage number are two important aspects of cell culture. These values help to determine the cell counts and the quality of cell culture. Population doubling is a measurement of time. In contrast, passage number is an integral measurement of the number of times the cells have been subcultured from primary cell culture. These values are very important in determining the quality of the cell culture and for various downstream experimental activities.
CONTENTS
1. Overview and Key Difference
2. What is Population Doubling
3. What is Passage Number
4. Similarities Between Population Doubling and Passage Number
5. Side by Side Comparison – Population Doubling vs Passage Number in Tabular Form
6. Summary
What is Population Doubling?
Population doubling is the time it takes to double the number of cells in a population. Population doubling is a measurement of time; this is often a measure in seconds. In contrast, population doubling level is the number of times population doubling can be achieved. You can determine the population doubling level using the following formula:
Population doubling level = 3.32 (log (total viable cells at harvest / total viable cells at seed))
The concept of population doubling can give you a rough estimation of the cell count in a cell culture. Therefore, scientists who perform cell culture experiments can decide on what type of experiment they should perform using population doubling,
What is Passage Number?
Passage number is a numerical value which defines the number of subcultures performed for a given primary cell culture. The primary cell culture is the first isolate of a cell. Thus, the passage number defines the age of a cell. Passaging of cells results in subcultures of the primary cell culture.
Passaging of cells in a cell culture is essential in order to maintain the viability of the particular cells. Hence, passage number is an important consideration when using cells for experiments. Passage number does not provide any information on the cell count. Cell lines with low passage numbers are generally recommended for experiments as they are considered to be relatively new in comparison to cell lines with high passage numbers.
What are the Similarities Between Population Doubling and Passage Number?
- Population Doubling and Passage Number are important in determining the quality of cell culture experiments.
- They explain the suitability of cells for a particular experiment.
What is the Difference Between Population Doubling and Passage Number?
Population doubling refers to the measurement of the time it takes to double the cell population. In contrast, passage number is a value of the number of times a particular cell culture is passaged. So, this is the key difference between population doubling and passage number. The other significant difference between population doubling and passage number is that population doubling leads to the cell count of a particular cell population while passage number leads to the age of the particular cell population.
The below infographic presents more information on the difference between population doubling and passage number comparatively.
Summary – Population Doubling vs Passage Number
In brief, population doubling refers to the time taken to double the cell count whereas passage number refers to the number of subculturings done to the initial primary culture. Thus, according to these definitions, population doubling is a measure of time whereas passage number is not. However, both measurements play an important role in determining the suitability of cells for a particular assay or an experiment. Thus, this is a summary of the difference between population doubling and passage number.
Reference:
1. “Cell Culture – An Introduction.” Cell Culture – Introduction | ABM Inc., Available here.
Image Courtesy:
1. “Cell Culture” By Umberto Salvagnin (CC BY 2.0) via Flickr