Chapter 16 Prokaryotes and Viruses
1. The first form of life was probably ____________and may have begun____________. The first form of life was probably prokaryotic and may have begun 3.9 billion years ago.
2. List and briefly describe the 2 prokaryotic domains:
1. Achaea (means ancient)
--lives in some of the most extreme conditions
--these habitats, while harsh compared with other earth environments today, may resemble the conditions that existed on early earth.
--Achaea and bacteria diverged very early in the evolution from ancient prokaryotic ancestors. 2. Bacteria --Scientists place the two groups of prokaryotes in separate domains partly because of key differences in the information contained in their nucleic acids (DNA and RNA). There are also differences in RNA polymerases --Bacteria polymerases are small and simple, while Achaea polymerases are complex. --Introns, the noncoding portions of genes, are absent in bacteria but are present in some Achaea. --Bacterial cell walls contain a polymer called peptidoglycan and is not found in Achaea.
3. List and briefly describe or draw 3 shapes of bacteria: a. Spherical—spherical bacteria are called cocci from the greek word for “berries.” Some species form clusters of spherical cells, while others form chains. b. Rod-shaped—rod-shaped bacteria in your intestines are bacilli. The e.coli bacteria in your intestines are bacilli. c. Curved or spiral-shaped—the largest spiral-shaped…