Light Microscope and Bacterial Growth
When using a light microscope, always start with the lowest magnification objective lens first. Place your thinly sliced sample (like onion epidermis) on a slide, add a few drops of stain such as iodine, and cover with a coverslip before examining.
Bacteria multiply through a process called binary fission - one cell simply divides into two cells. The time it takes for bacteria to divide is called the mean division time. Under ideal conditions, some bacteria can divide every 20 minutes!
You can calculate future bacterial populations by multiplying the current population by 2 for every mean division time that passes. For example, starting with 4 bacteria with a 30-minute division time, after 4 hours (8 divisions), you'll have 1,024 bacteria.
Did you know? If bacteria could continue dividing without limitations, a single bacterium dividing every 20 minutes would produce a mass of bacteria greater than the Earth in just a few days! Fortunately, environmental factors limit their growth.
