There are two competing groups of models for the evolutionary origin of the eukaryotic flagellum (referred to as a cilium below to distinguish it from its bacterial counterpart). Evolution of flagella - Symbiotic/endosymbiotic/exogenous models. These models argue some version of the idea that the cilium evolved from a symbiotic spirochete that attached to a primitive eukaryote or archaebacterium (archaea). The modern version of the hypothesis was first proposed by Lynn Margulis (as Sagan (1967): Margulis w ...

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Evolution of flagella, Evolution of flagella - The eukaryotic flagellum, Evolution of flagella - Symbiotic/endosymbiotic/exogenous models, Evolution of flagella - Endogenous/autogenous/direct filiation models, Evolution of flagella - The bacterial flagellum, Evolution of flagella - The archaeal flagellum, Evolution of flagella - Further research

Read more here: » Evolution of flagella: Encyclopedia II - Evolution of flagella - The eukaryotic flagellum

Over time, our understanding of the relationships between living things has changed. The greatest change was the widespread acceptance of evolution as the mechanism of biological diversity and species formation. After this, it became generally understood that classifications ought to reflect the phylogeny of organisms, where each taxon should originate from a single ancestral form. In some systems it is generally encouraged that taxa should b ...

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Linnaean taxonomy, Linnaean taxonomy - Example classification: humans, Linnaean taxonomy - Nomenclature, Linnaean taxonomy - Later developments, Linnaean taxonomy - Quotations, Linnaean taxonomy - Reference

Read more here: » Linnaean taxonomy: Encyclopedia II - Linnaean taxonomy - Later developments

Definition and meaning of Archaebacteria:

Archaebacteria - an ancient group of prokaryotes, over 3.5 billion years old; sometimes this group is placed into a separate kingdom, the Archaea. Most biologists currently place it within the Kingdom Monera. Archaebacteria inhabit extreme environments

(Source: US National Oceanic and Atmospheric Administration (NOAA) )

Also see these pages: Oceanography, Oceanography Sitemap, Coral Reef, Environment, Sustainability, Climate Change,

Cell walls of bacteria are primarily used for protection against hostile environments or, in the case of pathogenic bacteria, against the immune system of the host. They contain peptidoglycan, which can be made visible in Gram-positive bacteria by Gram staining. The cell walls of bacteria are also vital for containing the high osmotic pressure inside bacterial cells caused by the high concentration of solutes in the cytoplasm. This pressure can often be as high as 15 atmospheres. Many antibiotics, including penicillin an ...

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Cell wall, Cell wall - Plant cell walls, Cell wall - Composition of plant cell walls, Cell wall - Algal cell walls, Cell wall - Diatom cell walls, Cell wall - Prokaryotic cell walls, Cell wall - Fungal cell walls, Cell wall - Pictures

Read more here: » Cell wall: Encyclopedia II - Cell wall - Prokaryotic cell walls

Main article: Comparative genomics Comparison of genomes has resulted in some surprising biological discoveries. If a particular DNA sequence or pattern is present among many members of a clade, that sequence is said to have been conserved among the species. Evolutionary conservation of a DNA sequence may imply that it confers a relative selective advantage to the organisms that possess it. Conservation also suggests that sequence has functional significance. It may be a protein coding sequence or regulatory region. Experimenta ...

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Genomics, Genomics - History, Genomics - The growth of the omics, Genomics - Comparative genomics, Genomics - Genetic similarity

Read more here: » Genomics: Encyclopedia II - Genomics - Comparative genomics

Whereas Linnaeus classified for ease of identification, it is now generally accepted that classification should reflect the Darwinian principle of common descent. Since the 1960s a trend called cladistic taxonomy or cladism has emerged, arranging taxa in an evolutionary tree. If a taxon includes all the descendants of some ancestral form, it is called monophyletic, as opposed to paraphyletic. Other groups are called polyphyletic. A new formal code of nomenclature, the PhyloCode, is currently under development, intended to deal with clades rather than taxa. It is unclear, ...

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Scientific classification, Scientific classification - Modern developments, Scientific classification - Early systems, Scientific classification - Linnaeus, Scientific classification - Examples, Scientific classification - Group suffixes

Read more here: » Scientific classification: Encyclopedia II - Scientific classification - Modern developments

Plankton are primarily divided into broad functional (or trophic level) groups: Phytoplankton (from Greek phyton, or plant), autotrophic pro- or eukaryotic algae that live near the water surface where there is sufficient light to support photosynthesis. Among the more important groups are the diatoms, cyanobacteria and dinoflagellates. Zooplankton (from Greek zoon, or animal), small protozoans or metazoans (e.g. crustaceans and other animals) that feed on other plankton. Some of the eggs and ...

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Plankton, Plankton - Definitions, Plankton - Functional groups, Plankton - Size groups, Plankton - Distribution, Plankton - Biogeochemical significance, Plankton - Cultural references

Read more here: » Plankton: Encyclopedia II - Plankton - Functional groups

Main Article: Eukaryotic translation In eukaryotes, transcription occurs in the nucleus, then the mRNA moves to the cytoplasm for the translation to occur. The mRNA is spliced with 5' cap and 3' poly-A-tail and then transported. Initiation is described well below, elongation and termination proceed similarly to that in prokaryotes. Translation genetics - Initiation. Initiation of translation involves an interaction of some proteins with a special tag bound to 5'-end of the mRNA molecu ...

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Translation genetics, Translation genetics - Basic mechanisms, Translation genetics - Prokaryotic translation, Translation genetics - Initiation, Translation genetics - Elongation, Translation genetics - Termination, Translation genetics - Eukaryotic translation, Translation genetics - Initiation, Translation genetics - Translation by hand

Read more here: » Translation genetics: Encyclopedia II - Translation genetics - Eukaryotic translation

Mammalian cytochrome P450 oxidases have about 500 amino acids and a heme (hæm) group at the active site. Most can metabolize multiple substrates, and many can catalyze multiple reactions, which accounts for their central importance in metabolizing the potentially endless variety of endogenous and exogenous molecules. Most animal cytochromes P450 have a cofactor cytochrome P450 reductase and require the nucleoside cofactor NADPH and molecular oxygen (O2) to function. The Human Genome Project has identified 63 hu ...

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Cytochrome P450 oxidase, Cytochrome P450 oxidase - Molecular biology, Cytochrome P450 oxidase - Nomenclature, Cytochrome P450 oxidase - CYP Families in humans, Cytochrome P450 oxidase - Other specific CYP functions

Read more here: » Cytochrome P450 oxidase: Encyclopedia II - Cytochrome P450 oxidase - Molecular biology

It is often stated that a particular organism shares X percent of its DNA with humans. This number indicates the percentage of base pairs that are identical between the two species. Here is a list of genetic similarity to humans, with sources, where known. These numbers were found in various secondary sources, and were likely derived from differing methodologies (such as DNA-DNA hybridization or sequence alignment) which might give different results applied to the same pair of species. Therefore, they shoul ...

See also:

Genomics, Genomics - History, Genomics - The growth of the omics, Genomics - Comparative genomics, Genomics - Genetic similarity

Read more here: » Genomics: Encyclopedia II - Genomics - Genetic similarity

Analysis of DNA sequences suggests that horizontal gene transfer has also occurred within eukaryotes, from their chloroplast and mitochondrial genome to their nuclear genome. As stated in the endosymbiotic theory, chloroplasts and mitochondria probably originated as bacterial endosymbionts of a progenitor to the eukaryotic cell. There is also recent evidence that the adzuki bean beetle has somehow acquired genetic material f ...

See also:

Horizontal gene transfer, Horizontal gene transfer - Prokaryotes, Horizontal gene transfer - Eukaryotes, Horizontal gene transfer - Evolutionary theory

Read more here: » Horizontal gene transfer: Encyclopedia II - Horizontal gene transfer - Eukaryotes

Not all species of fungi have cell walls but in those that do, the cell walls are composed of cellulose, glucosamine, and chitin, the same carbohydrate that gives strength to the exoskeletons of insects. They serve a similar purpose to those of plant cells, giving fungal cells rigidity and strength to hold their shape and preventing osmotic lysis. It also limits the entry of molecules that may be toxic to the fungus, like plant-produced and synthetic fungicides. The composition, properties, and form of the fungal cell wall change during ...

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Cell wall, Cell wall - Plant cell walls, Cell wall - Composition of plant cell walls, Cell wall - Algal cell walls, Cell wall - Diatom cell walls, Cell wall - Prokaryotic cell walls, Cell wall - Fungal cell walls, Cell wall - Pictures

Read more here: » Cell wall: Encyclopedia II - Cell wall - Fungal cell walls

Babies are particularly subject to accumulation of gas in the stomach whilst feeding, and this can cause considerable agitation to the child unless it is burped. The act of burping an infant involves placing the child in a position conducive to gas expulsion (for example over the adult's shoulder, with the infant's stomach resting on the adult's chest) and then lightly patting or rubbing it on the lower back so that it burps. Because burping can cause vomiting in infants, a euphemistically-named burp cloth or burp pad is sometimes employed on the ...

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Burping, Burping - Physiology, Burping - Social context and etiquette, Burping - Infant burping, Burping - Burped speech, Burping - In animals

Read more here: » Burping: Encyclopedia II - Burping - Infant burping

It is possible to voluntarily induce burping by swallowing air and then expelling it, and by manipulation of the vocal tract produce burped speech. While this is often employed by children as a means of entertainment or competition, it can also act as an alternative means of vocalisation for people who have undergone a laryngectomy, with the burp replacing laryngeal phonation. This is known as esophageal speech. ...

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Burping, Burping - Physiology, Burping - Social context and etiquette, Burping - Infant burping, Burping - Burped speech, Burping - In animals

Read more here: » Burping: Encyclopedia II - Burping - Burped speech

Horizontal gene transfer is a potential confounding factor in inferring phylogenetic trees based on the sequence of one gene. For example, given two distantly related bacteria that have exchanged a gene, a phylogenetic tree including those species will show them to be closely related because that gene is the same, even though most other genes have substantially diverged. For this reason, it is often ideal to use other information to infer robust phylogenies, such as the presence or absence of genes, or, more commonly, to include ...

See also:

Horizontal gene transfer, Horizontal gene transfer - Prokaryotes, Horizontal gene transfer - Eukaryotes, Horizontal gene transfer - Evolutionary theory

Read more here: » Horizontal gene transfer: Encyclopedia II - Horizontal gene transfer - Evolutionary theory

Main articles: History of biology, History of medicine, History of genetics Major discoveries in biology include: Cell theory Germ theory of disease Genetics Evolution DNA ...

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Biology, Biology - Biological Phenomena, Biology - Branches of Biology, Biology - Principles of biology, Biology - Universality: Biochemistry cells and the genetic code, Biology - Evolution: The central principle of biology, Biology - Diversity: The variety of living organisms, Biology - Continuity: The common descent of life, Biology - Homeostasis: Adapting to change, Biology - Interactions: Groups and environments, Biology - Scope of biology, Biology - Structure of life, Biology - Physiology of organisms, Biology - Diversity and evolution of organisms, Biology - Interactions of organisms, Biology - History of the word biology, Biology - History, Biology - Related topics

Read more here: » Biology: Encyclopedia II - Biology - History

Since methionine is an essential amino acid, it cannot be synthesized in humans. However, in plants and microorganisms, methionine is synthesized from aspartic acid and cysteine. First, aspartic acid is converted to β-aspartyl-semialdehyde, an important intermediate in the biosynthesis of methionine, lysine, and, threonine. Of homoserine by homoserine acyltransferase, puts a good leaving group on homoserine allowing it to react with cysteine to produce cystathionine. Enzymatic cleavage of cystathionine yilds homocysteine, which can then be ...

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Methionine, Methionine - Biosynthesis, Methionine - Other Biochemical Pathways

Read more here: » Methionine: Encyclopedia II - Methionine - Biosynthesis

Formation of a biofilm begins with the attachment of free-floating microorganisms to a surface. These first colonists adhere to the surface initially through weak, reversible van der Waals forces. If the colonists are not immediately separated from the surface, they can anchor themselves more permanently using cell adhesion molecules such as pili. The first colonists facilitate the arrival of other cells by providing more diverse adhesion sites and beginning to build the matrix that holds the biofilm together. Some species are not abl ...

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Biofilm, Biofilm - Formation, Biofilm - Properties, Biofilm - Examples

Read more here: » Biofilm: Encyclopedia II - Biofilm - Formation

The enzymes isolated from some extremophiles have proven to be of great use in the biotechnology industry, able to function under conditions that would denature enzymes taken from most "normal" organisms. The most commonly used DNA polymerase for the polymerase chain reaction technique is Taq DNA polymerase, originally isolated from Thermus aquaticus, a bacterial species found in surface aquatic locations such as Yellowstone National Park hot springs. For a few PCR app ...

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Thermophile, Thermophile - Importance of enzymes from thermophiles, Thermophile - Some thermophilic organisms, Thermophile - Resources

Read more here: » Thermophile: Encyclopedia II - Thermophile - Importance of enzymes from thermophiles

Main articles: History of biology, History of medicine, History of genetics Major discoveries in biology include: Cell theory Germ theory of disease Genetics Evolution DNA ...

See also:

Biology, Biology - Principles of biology, Biology - Universality: Biochemistry cells and the genetic code, Biology - Evolution: The central principle of biology, Biology - Diversity: The variety of living organisms, Biology - Continuity: The common descent of life, Biology - Homeostasis: Adapting to change, Biology - Interactions: Groups and environments, Biology - Scope of biology, Biology - Structure of life, Biology - Physiology of organisms, Biology - Diversity and evolution of organisms, Biology - Interactions of organisms, Biology - History of the word biology, Biology - History

Read more here: » Biology: Encyclopedia II - Biology - History

Subsurface mining often progresses below the water table, in which case water must be constantly pumped out of the mine in order to prevent flooding. When a mine is abandoned, the pumping will cease and the water table will return to its former position, flooding the mine. The introduction of water is the initial step in most acid rock drainage situations. Tailings piles or ponds may also be a source of acid rock drainage. Metal mines may generate highly acidic discharges where the ore is a sulfide or is associated with pyrites. In th ...

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Acid mine drainage, Acid mine drainage - Occurrence, Acid mine drainage - Chemistry, Acid mine drainage - Effects, Acid mine drainage - Effects on pH, Acid mine drainage - Yellow boy, Acid mine drainage - Heavy metal contamination, Acid mine drainage - Treatment, Acid mine drainage - Oversight, Acid mine drainage - Methods, Acid mine drainage - List of acid mine drainage sites worldwide, Acid mine drainage - North America, Acid mine drainage - Europe, Acid mine drainage - Oceania

Read more here: » Acid mine drainage: Encyclopedia II - Acid mine drainage - Occurrence

While botany encompasses the study of plants, zoology is the branch of science that is concerned about the study of animals and anthropology is the branch of biology to study human beings. However, at the molecular scale, life is studied in the disciplines of molecular biology, biochemistry, and molecular genetics. At the next level of the cell, it is studied in cell biology, and at multicellular scales, it is examined in physiology, anatomy, and histology. Developmental biology studies life at the level of an ...

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Biology, Biology - Biological Phenomena, Biology - Branches of Biology, Biology - Principles of biology, Biology - Universality: Biochemistry cells and the genetic code, Biology - Evolution: The central principle of biology, Biology - Diversity: The variety of living organisms, Biology - Continuity: The common descent of life, Biology - Homeostasis: Adapting to change, Biology - Interactions: Groups and environments, Biology - Scope of biology, Biology - Structure of life, Biology - Physiology of organisms, Biology - Diversity and evolution of organisms, Biology - Interactions of organisms, Biology - History of the word biology, Biology - History, Biology - Related topics

Read more here: » Biology: Encyclopedia II - Biology - Branches of Biology