Bacteria occupy their own domain of life. The domain Eubacteria is tremendously diverse and embraces no fewer than 30 distinct phyla, according to the LSPN classification schema. Because of the eagerness with which bacteria exchange genes across species barriers via lateral gene transfers, firm classifications according to lineage are difficult to establish with certainty.
Taxonomists divide life into major suborders, chiefly domain, kingdom, phylum and class. Bacteria belong to the domain Eubacteria, which is one of the three domains of life on Earth. According to Wikipedia, the old designation for bacteria, Prokaryota, can be used only to distinguish bacteria and archaeans from the plants, animals and fungi of Eukaryota and is therefore of limited value. Within Eubacteria, organisms are grouped into phyla and classes, though these levels of classification were developed for eukaryotes and cannot take into account the frequency with which bacteria trade genetic material.
Traditional lines of phylogeny begin to break down at levels below class, as bacterial "species" rarely exist in genetic isolation, notes Wikipedia. Lower-level classification thus becomes largely a matter of opinion, as the majority-similarity rule for identifying a bacterial species, if applied to mammals, would group humans, apes and monkeys together as a single "species."Learn More
The organelles that contain digestive enzymes are called lysosomes. These cellular structures primarily function for the breakdown of complex molecular substances, such as carbohydrates, lipids, proteins and nucleic acids.Full Answer >
Nucleotides are the monomer of DNA. They are made of a 5-carbon sugar (deoxyribose), a phosphate group, and a nitrogenous base bound to the sugar. The four different types of nucleotides are adenine (A), thymine (T), guanine (G) and cytosine (C).Full Answer >
Speciation, commonly known as macroevolution, is supported by several lines of evidence, including direct observation, genetic mapping and the fossil record. Several populations have been observed in the act of splitting into new species. Comparison of genomic sequences between species are most easily explained as a result of recent common ancestry and an extensive fossil record has yielded numerous transitional fossils.Full Answer >
Genetic variation is important to evolution because it helps to maintain the health of a population by constituting alleles that may be useful in overcoming stresses such as diseases and pests. Without genetic variation, some of the fundamental mechanisms of evolutionary changes would not operate.Full Answer >