Concept 27.1

Question:
I. Identify and explain at least 2 examples of adaptations that enable prokaryotes to survive in environments too harsh for other organisms.

Answer:
a) Adaptations include the capsule, plasmids, and the formation of endospores.

Question:
II. Contrast the cellular and genomic organization of prokaryotes and eukaryotes.

Answer:
a) Prokaryotes vs Eukaryotes: prokaryotes lack a nucleus enclosed by membranes, lack other internal compartments bounded by a membrane so instead they use the infolded regions of the plasma membrane to perform many metabolic functions including cellular respiration and photosynthesis, while eukaryotes have internal compartments bounded by a membrane, have smaller and simpler genomes than eukaryotes, may also have smaller rings of DNA, plasmids, that consist of only a few genes unlike in eukaryotes; prokaryotes can survive in most environments without their plasmids because essential functions are programmed by the chromosomes.
b) Prokaryotic cells generally lack the internal compartmentalization of eukaryotic cells. Prokaryotic genomes have much less DNA than eukaryotic genomes, and most of this DNA is contained in a single ring-shaped chromosome located in a nucleoid region rather than within a true membrane-bounded nucleus. In addition, many prokaryotes also have plasmids, small ring-shaped DNA molecules, containing a few genes.

Question:
III. Explain how rapid reproduction allows prokaryotes to adapt to changing environments.

Answer:
a) Prokaryotes can adapt quickly to changes in their environment through evolution by natural selection. Because of prokaryotes' rapid reproduction, mutations that confer greater fitness can swiftly become more common in a population. Horizontal gene transfer also facilitates rapid evolution in prokaryotes.
b) Rapid reproduction enables a favorable mutation to spread quickly through a prokaryotic population by natural selection.