Chapter 18: Viruses and Prokaryotes

Section One: Studying Viruses and Prokaryotes Bacteria Pathogen: any living organism or particle that can cause an infectious disease Living Virus An infectious particle made only of a strand of DNA or RNA surrounded by a protein coat Non living Cannot be targeted by antibiotics Cannot reproduce by themselves Rely on living cells to reproduce and make proteins

Section Two: Viral Structure and Reproduction Capsid: a protein shell that holds the genetic material of the virus (sometimes surrounded by a lipid envelope) Bacteriophage: virus that infects bacteria

Section Two: Viral Structure and Reproduction Virus Reproduction Happens through host cell infection Lytic an infection pathway in which the host cell bursts, releasing the viral offspring into the host’s system, where each then infects a new cell Lysogenic A phage combines its DNA into the host cell’s DNA, then divides the host cell so that its DNA is passed on Can enter the lytic cycle or continue dividing

Section Two: Viral Structure and Reproduction

Section Three: Viral Diseases Vaccines A substance that stimulates the body’s own immune response against the invasion of microbes (bacteria or viruses) Made from weakened or dead bacteria and viruses

Section Four: Bacteria and Archae Have plasmids Move by flagella: long, whip like tail used for movement Have cell wall Bacteria: have peptidoglycan in their cell wall Archae: have lipids in their cell wall Both can reproduce through conjugation: exchange of parts of chromosomes through a bridge of pill formed by contact of two or more cells

Section Six: Antibiotic Resistance Bacteria can evolve resistance to antibiotics Caused by inappropriate or incomplete use of antibiotics Resistance occurs through natural selection Those that survive being partially treated by antibiotics or are have genes that make them resistant pass on their genes and resistance