Michael Surette

The way that DNA encodes the instructions for proteins is through a set of four molecules called bases, each of which represents a letter of the genetic code (A = adenine, C = cytosine, G = guanine, and T = thymine). The bases are made of carbon and nitrogen rings and are bound to a sugar and a phosphate to form a nucleotideThe nucleotides are connected together to form a long chain with the bases pointing out.

When you're studying microbiology, you need to know the key differences between the three domains of life, how scientists name and classify organisms, and how scientists identify microorganisms.Differences among bacteria, archaea, and eukaryotic microorganismsThere are three domains of life: bacteria (also known as eubacteria), archaea, and eukarya.

Prokaryotic cells come in many different shapes and sizes that you can see under a microscope. A description of the shape of a cell is called the cell morphology. The most common cell morphologies are cocci (spherical) and bacilli (rods).Coccibacillus are a mix of both, while vibrio are shaped like a comma, spirilla are shaped like a helix (a spiral, sort of like a stretched-out Slinky), and spirochetes are twisted like a screw.

When it comes to infectious agents, like bacteria, viruses, and fungi, cleaning is an important way to reduce their spread. What people are really trying to do when they wash their hands or wipe a surface is reduce the number of pathogenic microbes present. In reality, all surfaces, including the surfaces of the human body, are teeming with microbes, most of which are just minding their own business.

Before genes can be passed from parent cells to their progeny, a copy of the genome has to be made in a process called replication. For circular chromosomes, like those in bacteria and archaea, replication begins at the origin of replication and proceeds in two directions away from that point, simultaneously. The steps involved in DNA replication must happen in a precise order: Supercoiled double-stranded DNA is relaxed by an enzyme called topoisomerase (or gyrase) and then unwound by an enzyme called helicase, which opens up the two strands in one area at a time.

Since the beginning of their widespread use in 1943, antibiotics have saved countless lives and changed the way medicine is practiced. Before their discovery, people suffered or died from infectious diseases that today are a mere annoyance, like sexually transmitted diseases and post-operative infections. Today antibiotics are essential in treating life-threatening bacterial infections, like pneumonia and sepsis, and are used preventively in a number of medical procedures (like surgery) and treatments (like cystic fibrosis).

To keep the many organisms on earth straight, in the 18th century the Swedish botanist Carl Linnaeus developed a simple nomenclature system to classify and name all organisms including bacteria. This system ranks all organisms using the following headings, shown with the example of the bacterium E. coli. Domain: Bacteria Phylum: Proteobacteria Class: Gammaproteobacteria Order: Enterobacteriales (Order names always end in –iales.

There are three domains of life: Bacteria (also known as Eubacteria), Archaea, and Eukarya. The Bacteria and Archaea are made up entirely of microorganisms; the Eukarya contains plants, animals, and microorganisms such as fungi and protists. The Bacteria and Archaea have been grouped together and called Prokaryotes because of their lack of a nucleus, but the Archaea are more closely related to the Eukaryotes than to the Bacteria.