Kingdom Monera

1.         General

            a.          Prokaryote means “before a nucleus.”

            b.         Prokaryotes are single-celled organisms. They are the smallest, simplest organisms.

            c.         The group includes

                        i.         Archaebacteria - Found in anaerobic conditions with high [salt], high temperature, and low pH. These are believed to be the conditions on the early Earth. Earth’s early atmosphere did not contain oxygen. The earliest organisms were anaerobic.

                        ii.        Eubacteria - This group includes the traditional bacteria and is the largest of the two.

            d.         They are found in nearly every habitat studied, including some that no other organism is able to withstand.

            e.         Bacteria have a cell wall, a cell membrane surrounds the cell but no membrane-bound organelles such as a nucleus, mitochondria, chloroplasts, Golgi apparatus, or ER. Some are covered by a layer of “slime” called a capsule. Some have flagella for locomotion.

            f.         They show 3 basic shapes

                        i.         Cocci - spherical

                        ii.        Bacilli - rod-shaped

                        iii.       Spirilla - spiral

2.         Respiration

            a.         Obligate aerobes - must have oxygen.

            b.         Obligate anaerobes - cannot survive in the presence of oxygen.

            c.         Facultative anaerobes - will use oxygen if present but don’t need it.

3.         Nutrition

            a.         Most are heterotrophs although some are autotrophs. The autotrophic bacteria either use chemicals as a source of energy (chemoautotrophs) or are photosynthetic (photoautotrophs).

            b.         Some are parasites which live off a living host.

            c.         Some are saprobes, feeding off dead organisms and waste (i.e., decomposers).

4.         Reproduction

            a.         Prokaryotes have a single circular chromosome attached to the inside of the plasma membrane.

            b.         Asexual - binary Fission

                        i.         Prokaryotes reproduce by simply splitting in two.

                        ii.        The DNA is copied and the cell divides into two identical cells.

            c.         Sexual - conjugation

                        i.         Sexual reproduction combines genes from two different individuals and increases variation. Prokaryotes do not technically reproduce sexually can mix genes with one another.

                        ii.        Conjugation - Two cells join briefly and one cell donates some DNA (called a plasmid) to the other one. Sometimes part of the cell’s chromosome is donated as well.

                        iii.       Transformation - Bacteria can also pick up pieces of DNA from the environment.

                        iv.       Transduction - sometimes viruses transfer pieces of DNA from one cell to another.

            d.         Mutation is a large source of genetic diversity in bacteria.

            e.         Endospores

                        i.         some bacteria form endospores when environmental conditions become unfavorable.

                        ii.        Endospores are DNA and a small amount of cytoplasm enclosed in a tough cell wall. They are resistant to extremes in temperature, drying, and harsh chemicals.