eukaryotic

Examples of eukaryotic in the following topics:

• Characteristics of Eukaryotic DNA

  • Prokaryotic cells are known to be much less complex than eukaryotic cells since eukaryotic cells are considered to be present at a later point of evolution.
  • It is probable that eukaryotic cells evolved from prokaryotic cells.
  • All extant eukaryotes have cells with nuclei; most of a eukaryotic cell's genetic material is contained within the nucleus.
  • All extant eukaryotes have these cytoskeletal elements.
  • A major DNA difference between eukaryotes and prokaryotes is the presence of mitochondrial DNA (mtDNA) in eukaryotes.

• Shared Features of Archaea and Eukaryotes

  • Archaea possess genes and several metabolic pathways that are more closely related to those of eukaryotes than prokaryotes.
  • The evolutionary relationship between archaea and eukaryotes remains unclear.
  • The leading hypothesis is that the ancestor of the eukaryotes diverged early from the Archaea, and that eukaryotes arose through fusion of an archaean and eubacterium, which became the nucleus and cytoplasm.
  • The chromosomes replicate from multiple starting-points (origins of replication) using DNA polymerases that resemble the equivalent eukaryotic enzymes.
  • Eukaryotes are colored red, archaea green and bacteria blue.

• Prokaryotic versus Eukaryotic Gene Expression

  • Prokaryotes regulate gene expression by controlling the amount of transcription, whereas eukaryotic control is much more complex.
  • The process occurs in both prokaryotic and eukaryotic cells, just in slightly different manners.
  • Eukaryotic cells, in contrast, have intracellular organelles that add to their complexity.
  • In eukaryotic cells, the DNA is contained inside the cell's nucleus where it is transcribed into RNA.
  • Eukaryotic gene expression is regulated during transcription and RNA processing, which take place in the nucleus, and during protein translation, which takes place in the cytoplasm.

• Phylogeny of the Eukarya

  • Eukaryotes may more formally be referred to as the taxon Eukarya or Eukaryota.
  • All large complex organisms are eukaryotes, including animals, plants, and fungi.
  • Eukaryotes are split into 6, subdivisions, referred to as kingdoms .
  • It has been estimated that there may be 75 distinct lineages of eukaryotes.
  • This is one hypothesis of eukaryotic relationships.

• Endosymbiosis and the Evolution of Eukaryotes

  • Eukaryotes may have been a product of one cell engulfing another and evolving over time until the separate cells became a single organism.
  • To fully understand eukaryotic organisms, it is necessary to understand that all extant eukaryotes are descendants of a chimeric organism that was a composite of a host cell and the cell(s) of an alpha-proteobacterium that "took up residence" inside the host.
  • Endosymbiotic events probably contributed to the origin of the last common ancestor (LCA) of today's eukaryotes.
  • In 1981 she argued that eukaryotic cells originated as communities of interacting entities, including endosymbiotic spirochetes that developed into eukaryotic flagella and cilia.
  • Describe the general concept of endosymbiosis and the evolution of eukaryotes

• Endosymbiotic Theory and the Evolution of Eukaryotes

  • There are several other competing hypotheses as to the origin of eukaryotes and the nucleus.
  • If the eukaryotic nucleus evolved this way, we would expect one of the two types of prokaryotes to be more closely-related to eukaryotes.
  • Most interestingly, the eukaryote-first hypothesis proposes prokaryotes actually evolved from eukaryotes by losing genes and complexity .
  • Three alternate hypotheses of eukaryotic and prokaryotic evolution are (a) the nucleus-first hypothesis, (b) the mitochondrion-first hypothesis, and (c) the eukaryote-first hypothesis.
  • Describe the genome fusion hypothesis and its relationship to the evolution of eukaryotes

• Historical Overview of Eukaryotes

  • Until more recent work, the historical view of eukaryotes has been anthropomorphic.
  • The various single-cell eukaryotes were originally placed with plants or animals when they became known.
  • This group was expanded until it encompassed all single-cell eukaryotes.
  • The eukaryotes came to be composed of four kingdoms: Kingdom Protista, Kingdom Plantae, Kingdom Fungi, and Kingdom Animalia.
  • The disentanglement of the deep splits in the tree of life only really got going with DNA sequencing, leading to a system of domains rather than kingdoms as top level rank being put forward by Carl Woese, uniting all the eukaryote kingdoms under the eukaryote domain .

• Control of Transcription in Archaea

  • Transcription and translation in archaea resemble these processes in eukaryotes more than in bacteria.
  • Archaea are genetically distinct from bacteria and eukaryotes, with up to 15% of the proteins encoded by any one archaeal genome being unique to the domain, even though most of these unique genes have no known function.
  • The proteins that archaea, bacteria and eukaryotes share form a common core of cell function, relating mostly to transcription, translation, and nucleotide metabolism.
  • Transcription and translation in archaea resemble these processes in eukaryotes more than in bacteria, with the archaean RNA polymerase and ribosomes being very close to their equivalents in eukaryotes.
  • Compare the archaea with bacteria and eukaryotes in terms of their general mechanisms of gene expression

• Newly Discovered Eukaryotes

  • There are many new species to be discovered, including eukaryotic species.
  • Considering how large an elephant is, this should point out how little we know about the numbers of microscopic eukaryotes that are yet to be discovered.
  • Of course we may never truly identify many eukaryotic species, since the rate of extinction has increased.
  • This does not include many microscopic eukaryotic groups.

• Initiation of Transcription in Eukaryotes

  • Initiation is the first step of eukaryotic transcription and requires RNAP and several transcription factors to proceed.
  • The features of eukaryotic mRNA synthesis are markedly more complex those of prokaryotes.
  • Each eukaryotic polymerase also requires a distinct set of transcription factors to bring it to the DNA template.
  • Eukaryotic pre-mRNAs undergo extensive processing after transcription, but before translation.
  • This interactive models the process of DNA transcription in a eukaryotic cell.