Copyright © 2019-2020 C.E. by Dustin Jon Scott
Introduction
Eukaryotes are organisms whose cells contain nuclear envelopes. Their protoplasm (an old scientific word for all the crap inside a cell) is divided into a cytoplasm (the material inside of the cell that lies outside of the nuclear envelope) and nucleoplasm (the material inside the nuclear envelope).
The Domain Eukaryota / clade eucarya is...
Evolutionary Origins
Eukaryotes seem to have evolved from within the genetic group of the archaea, which appears to the oldest domain of diversified life on planet Earth. There are some archaea, such as among the proteoarchaeota, who appear to be more closely related to the eucarya than they are to other prokaryotic archaea. This means that the eucarya are phylogenetically nested within the archaea; that eukaryotes are in fact a type of archaeon — at least genetically. While many eukaryotic cell structures appear to have been generated by multiple redundant copies of archaeal genes, there is still some debate over which cell type is the ancestral form: the simpler, prokaryotic cell type with its single, ring-shaped chromosome, or the far more complicated eukaryotic cell type with its multiple chromosomes and linear genome housed in a nuclear envelope. The nuclear compartmentalization commonality (NuCom) hypothesis states that the eukaryotic cell type, or perhaps a simpler "proto-eukaryotic" version of it, is actually the ancestral cell type. The karyogenic proto-coenocyte hypothesis has both eukaryotes and prokaryotes having evolved from large, multinucleate (i.e., syncytial) "super cells". Such hypotheses can be lumped together into "eukaryotes-first" models, which currently have to compete with the more mainstream "prokaryotes-first" model.
The Eukaryotic Cell Structure — Eukaryotic cells such as ours are far larger and more structurally complex than normal (prokaryotic) cells. |
|
Subsections
The Bone Zone: Get boned — osteology, the study of bones, and ichthyology, the subdiscipline of eukaryology dealing with creatures who have bones. Ichthyology generally focuses on the study of non-tetrapod fish. |
|
The Reptile Room: it’s reptilicious — herpetology, the subdiscipline of ichthyology dealing with the land-fish known as “tetrapods”. Generally focuses on the study of non-mammalian, non-avian tetrapods. |
|
Mammarama: It’s Lactastic — mammalogy, the subdiscipline of herpetology dealing with the lactating land-fish known as “mammals”. |
|
The Primatorium: Go Primal — primatology, the subdiscipline of mammalogy dealing with the tree rats known as “primates”. |
|
The Hominid Homepage: For All Your Homo-Needs — palæoanthropology. |
|
Religion & Spirituality — cultural anthropology. |
|
The Hive: Question. Subvert. Resist. — sociology & social ethology. |