RT Book, Section A1 Levinson, Warren A1 Chin-Hong, Peter A1 Joyce, Elizabeth A. A1 Nussbaum, Jesse A1 Schwartz, Brian SR Print(0) ID 1175824044 T1 Genetics T2 Review of Medical Microbiology & Immunology: A Guide to Clinical Infectious Diseases, 16e YR 2020 FD 2020 PB McGraw Hill PP New York, NY SN 9781260116717 LK accessmedicine.mhmedical.com/content.aspx?aid=1175824044 RD 2024/03/29 AB There are several unique aspects of microbial genetics that largely account for the great genotypic and phenotypic diversity, the ability to cause disease, and the propensity to develop resistance to virtually any antibiotic observed in bacteria. Bacteria have a simple genetic organization relative to eukaryotic organisms. They are haploid, usually possessing a single chromosome and therefore a single copy of each gene. This is in contrast to eukaryotic cells (such as human cells), which are diploid, meaning they have a pair of each chromosome and therefore have two copies of each gene. In diploid cells, one copy of a gene (allele) may be expressed as a protein (i.e., be dominant), whereas another allele may not be expressed (i.e., be recessive). In haploid cells, any gene that has acquired a mutation will result in a cell synthesizing either a mutant protein or no protein at all depending on the type of mutation.