BIO 1109 Lecture Notes - Herbaceous Plant, Lignin, Marchantiophyta
Document Summary
Summary of chapter 20: viruses, archea and bacteria. Viruses are noncellular, while prokaryotes are fully functioning organisms. All viruses have at least two parts: an outer capsid composed of protein subunits and an inner core of nucleic acid (dna or rna never both). Viruses are obligate intracellular parasites that can be maintained only inside living things (cannot multiply outside of cell), such as a chicken egg, or those propagated in cell (tissue) culture. The bacteria (domain bacteria) and archaea (domain archaea) are prokaryotes. Prokaryotic cells lack a nucleus and most of the other cytoplasmic organelles found in eukaryotic cells. Their chief method for achieving genetic variation is mutation, but genetic recombination by means of conjugation, transformation, and transduction has been observed. Prokaryotes differ in their need (and tolerance) for oxygen. There are obligate anaerobes, facultative anaerobes, and aerobic prokaryotes. Some prokaryotes are autotrophic, and some are heterotrophic. Bacteria are the more prevalent type of prokaryote.
