Bacteria are single celled organisms that have been around for millions of years. They belong to the Kingdom Bacteria. Since bacteria are single celled, they are a type of prokaryote, which means that they lack organelles and a nucleus. Bacteria come in three shapes: bacilli (rod shaped), cocci (spherical), and spirilla (spiral and corkscrew shaped). Some bacteria have flagella (tails) attached to them for movement. Bacteria reproduce asexually though binary fission. This is when a bacterium has grown to nearly double in size, replicates its DNA, and then divides in half. Binary fission produces two identical daughter cells. Many bacteria are also able to exchange genetic information through conjugation. During conjugation, a hollow bridge forms between the two cells and genes move from one cell to the other.
A virus is a particle of nucleic acid, protein, and sometimes lipids. Virus comes from the Latin word for poison. Viruses reproduce by infecting other cells. Viruses are considered nonliving because they cannot reproduce on their own. Viruses have a protein coat called a capsid. The virus can infect a cell through two different processes. The lytic cycle is when the virus injects its DNA into a cell. The virus takes over the bacterium’s metabolism, causing synthesis of new viruses. The viruses get assembled inside of the host cell. Once all of the viruses are assembled, they break the cell’s cell wall, releasing more viruses into your body. Then there is the lysogenic cycle. In this cycle, the virus injects its DNA into the host cell and the virus DNA inserts itself into the host cell’s DNA. The host cell will then replicate with the virus DNA in it. A virus can stay in this cycle for weeks or years. In this case, you would not even know you had the virus until the virus transitioned into the lytic cycle, at which point you would get sick.
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