By now, it is a well-understood fact that bacteria are microscopic, unicellular organisms that are found almost everywhere. The size of most bacteria falls between 0.2 to 2.0 micrometres in diameter.
One of the smaller bacteria is the Haemophilus influenzae, with a diameter of about 0.25 micrometres. One of the largest ever bacteria is the Thiomargarita namibiensis; it can grow up to 0.75 millimetres, which are large enough to be seen with the naked eye. E.coli bacteria ranges from 1.1 to 1.5 micrometres in diameter. If we were to scale this up to human proportions, then the smallest bacteria would be the size of a hand and the largest would be able to fit 30 train coaches within itself.
Interestingly, computational biologists have imposed an upper and a lower limit on size. These limitations are formed due to the space constraints in the bacteria. For instance, simulations have predicted that bacteria cannot grow any smaller than 0.2 micrometres because then, it would not have enough space to fit in all its cellular organelles. Without these organelles, it cannot perform vital cell functions that are required for sustaining life. On the other end of the spectrum, simulations have shown that bacteria cannot grow any larger than 0.90 millimetres as its energy demand will significantly increase. This means the bacteria needs to have extra ribosomes and it cannot fit all those within itself because of, again – space constraints.
However, scientists now know the minimum and maximum size limitations for bacteria. Based on these principles, we can effectively look for other life beyond earth. Explore other fascinating topics from cerebrum function to cryogenics only at BYJU’S. Alternatively, subscribe to BYJU’S YouTube channel to watch exciting videos on all things science.