Now that we have looked at cells and viruses let us study microscopy, the tactical field that uses microscopes to view objects and samples that cannot be seen with unaided eye. In order to study microscopy, comparative sizes need to be considered. Then we will study the two main types of microscopes the light microscope and the electron microscope. The electron microscope can be of two types scanning electron microscope and transmission electron microscope. Here is a brief outline for comparative sizes. Let us start with looking at the system used for size measurement.

Then, let us compare the sizes of different atoms, molecules microorganisms, micro organisms. And then let us compare the sizes of these atoms, molecules and organisms relative to the three modes of observation which are the naked eye, the light microscope and the electron microscope. Finally, we'll review the most common size ranges of microbial agents. The main physical characteristic to consider in microscopy is size. The measurement system is the metric system. The most common measurement is the micro meter, because most bacterial cells animal cells and plant cells are in the range of micro meter.

One micro meter corresponds to 10 to the power of minus six meters that is 1,000,001 micrometer is 1 million offer. meter. The graph on the top shows the schematic representation of different sizes, comparing water molecules. adenovirus equalize eye right let's paramecium and fly agaric also known commonly as Amanita muscaria, which is a mushroom and a person while atoms and small molecules are in the range of point one to one nanometer, I don't know viruses in the range of hundred nanometers almost equalize around two micron micro meter. red blood cell pen micro meter paramecium around 200 micrometers the mushroom, fly a Garrick around 10 centimeters tall, and a person an average of 1.75 meters tall. graph below shows the same range with a more detailed view of the measurements.

One important thing to note is that one micro meter corresponds to 1000 nanometers. In this diagram of relative size comparisons let us start by noticing that atoms and molecules are of the smallest sizes. Then come viruses like HIV poliovirus following our bacterial cells rickettsia cyanobacteria, Rod shaped spherical bacteria and archaea organisms then are the unicellular alga protozoa. And most fungi, such as East know, mall which is a type of fungi. And tapeworms are of course, and flukes as well are examples of multicellular organisms which are large enough for us to see with unaided eye ranging from a few millimeters to up to 10 meters As in the case of tapeworms. So, with our unaided eye, shown here in the pink is the range that we can see we can see up to 150 micrometers.

With light microscopes shown here in orange we can see from 50 millimeters up to 100 nanometers. And with the electron microscope we can see from a range of hundred micro meters all the way to one nanometer. One main point to note is that there is an overlap as you can see over here and here. Among the three modes of observation. When comparing the sizes of these three microorganisms, the protozoa bacteria, larger cells and viruses, the protozoa are the largest. Next are the bacteria and the archaea.

And finally, the viruses are the smallest organisms. Usually protozoa around the range of 100 micrometers diameter. Bacteria, larger cells are on one to five micrometers in diameter. Viruses are in nanometers that is $1,000 a micro meter. For example, the polio virus is around 20 nanometers in diameter. So in summary, there is a considerable overlap in what can be seen through analysis.

Microscope, light microscope and unaided eye, some microorganisms. Some organisms that is although macroscopic, such as flu, can reach up to a few centimeters and take one square can grow up to 20 meters are still studied by microbiologist. Viruses usually range somewhere between 20 and 300 nanometers. bacteria and archaea will sell somewhere between one to 10 micrometers. And protests are usually between 10 and 50 micrometers although there are certain exceptions and some may reach larger sizes. This concludes our study of comparative sizes