The first use of enzymes occurred more than 5,000 years ago, when people stored milk in animal stomachs, which contains enzymes called “rennet,” that turn milk into cheese. ...

The apicomplexa are a monophyletic group composed almost entirely of parasitic (ie, no free-living) species. Apicomplexa, along with ciliates and dinoflagellates, form a higher order group known as Alveolata. A major defining characteristic of the this group are flattened vesicle-like structures--called cortical alveolae ...

Protozoan organism, usually single-celled and heterotrophic (using organic carbon as a source of energy), belonging to any of the major lineages of protists and, like most protists, typically microscopic. All protozoans are eukaryotes and therefore possess a “true,” or membrane-bound, nucleus. ...

Infection with nontyphoidal serovars of Salmonella generally results in food poisoning. Infection usually occurs when a person ingests foods that contain a high concentration of the bacteria. Infants and young children are much more susceptible to infection, easily achieved by ingesting a small number of bacteria. In infants, infection through inhalation of bacteria-laden dust is possible. ...

Salmonellosis is an infection caused by Salmonella bacteria. Most people infected with Salmonella develop diarrhea, fever, vomiting, and abdominal cramps 12 to 72 hours after infection. In most cases, the illness lasts four to seven days, and most people recover without treatment.In some cases, the diarrhea may be so severe that the patient becomes dangerously dehydrated and must be hospitalized. ...

An exotoxin is a toxin that is produced by a bacterium and then released from the cell into the surrounding environment. The damage caused by an exotoxin can only occur upon release. As a general rule, enterotoxins tend to be produced by Gram-positive bacteria rather than by Gram-negative bacteria. There are exceptions, such as the potent enterotoxin produced by Vibrio ...

Clostridium botulinums is an anaerobic, Gram-positive, spore-forming rod that produces a potent neurotoxin. The spores are heat-resistant and can survive in foods that are incorrectly or minimally processed. Seven types (A, B, C, D, E, F and G) of botulism are recognized, based on the antigenic specificity of the toxin produced by each strain. ...

Botulinum toxin is among the most deadly naturally occuring Neurotoxins, produced by the naturally occurring Clostridium botulinum and causing the fatal disease Botulism. Minute doses of the toxin can be fatal and according to Arnon et al, "a single gram of crystalline toxin, evenly dispersed and inhaled, would kill more than 1 million people" ...

An antitoxin is an antibody with the ability to neutralize a specific toxin. Antitoxins are produced by certain animals, plants, and bacteria. Although they are most effective in neutralizing toxins, they can kill bacteria and other microorganisms. Antitoxins are made within organisms, but can be injected into other organisms, including humans. This procedure involves injecting an animal with a safe ...

Staphylococcus aureus is a gram-positive coccal bacterium that is a member of the Firmicutes, and is frequently found in the nose, respiratory tract, and on the skin ...

Anthrax is primarily a disease of herbivores caused by gram-positive, aerobic, spore-forming Bacillus anthracis. Humans are accidental hosts through the food of animal origin and animal products. ...

Clostridium tetani is a rod-shaped, anaerobic species of pathogenic bacteria, of the genus Clostridium. Like other Clostridium genus species, it is Gram-positive, and its appearance on a gram stain resembles tennis rackets or drumsticks.C. tetani is found as spores in soil or in the gastrointestinal tract of animals ...

The cytosol or cytoplasmic matrix is the liquid found inside cells. It constitutes most of the intracellular fluid (ICF). It is separated into compartments by membranes. For example, the mitochondrial matrix separates the mitochondrion into many compartments. ...

Rickets is defective mineralization or calcification of bones before epiphyseal closure in immature mammals due to deficiency or impaired metabolism of vitamin D, phosphorus or calcium potentially leading to fractures and deformity. ...

Pyruvic acid (CH3COCOOH) is the simplest of the alpha-keto acids, with a carboxylic acid and a ketone functional group. Pyruvate, the conjugate base, CH3COCOO−, is a key intermediate in several metabolic pathways. ...

An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a higher resolving power than light microscopes and can reveal the structure of smaller objects. A transmission electron microscope can ...

The three-carbon sugars formed when the unstable sugar breaks down are different from each other. Only one—glyceraldehyde-3-phosphate—can enter the following step. However, the unfavorable sugar, \text{DHAP}DHAPD, H, A, P, can be easily converted into the favorable one, so both finish the pathway in the end Energy-releasing phase. In this phase, each three-carbon sugar is converted into another three-carbon molecule, pyruvate, ...

Lysine (abbreviated as Lys or K),encoded by the codons AAA and AAG, is an α-amino acid that is used in the biosynthesis of proteins. I ...

DNA Polymerase I (or Pol I) is an enzyme that participates in the process of prokaryotic DNA replication. Discovered by Arthur Kornberg in 1956it was the first known DNA polymerase (and, indeed, the first known of any kind of polymerase). It was initially characterized in E. coli and is ubiquitous in prokaryotes. In E. coli and many other bacteria, the ...

Evolution is change in the heritable characteristics of biological populations over successive generations. Evolutionary processes give rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms, and molecules. ...

Oxidative phosphorylation (or OXPHOS in short) is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing energy which is used to reform ATP. In most eukaryotes, this takes place inside mitochondria. Almost all aerobic organisms carry out oxidative phosphorylation. This pathway is probably so pervasive because it is a highly efficient way of releasing energy, compared ...

Plants need food but they do not have to wait on people or animals to provide for them. Most plants are able to make their own food whenever they need it. This is done using light and the process is called photosynthesis. ...

Bacteria are microscopic single-celled organisms that thrive in diverse environments. They can live within soil, in the ocean and inside the human gut. Humans' relationship with bacteria is complex. Sometimes they lend a helping hand, by curdling milk into yogurt, or helping with our digestion. At other times they are destructive, causing diseases like pneumonia and MRSA. ...

Psychrophiles (cold-loving) can grow at 0oC, and some even as low as -10oC; their upper limit is often about 25oC. ...

Liquefaction[edit] Helium was first liquefied on July 10, 1908, by the Dutch physicist Heike Kamerlingh Onnes at the University of Leiden in the Netherlands.[2] At that time, helium-3 was unknown because the mass spectrometer had not yet been invented. In more recent decades, liquid helium has been used as a cryogenic refrigerant, and liquid helium is produced commercially for use ...

The ability to synthesize DNA from an RNA template, via reverse transcription, enables researchers to study RNA with the same molecular approaches used for DNA investigations. cDNA generated by reverse transcription can be amplified using polymerase chain reaction (PCR). ...

A genomic library is a collection of the total genomic DNA from a single organism. The DNA is stored in a population of identical vectors, each containing a different insert of DNA. In order to construct a genomic library, the organism's DNA is extracted from cells and then digested with a restriction enzyme to cut the DNA into fragments of ...

Electroporation is a physical transfection method that uses an electrical pulse to create temporary pores in cell membranes through which substances like nucleic acids can pass into cells. It is a highly efficient strategy for the introduction of foreign nucleic acids into many cell types, including bacteria and mammalian cells. ...

In molecular biology, DNA ligase is a specific type of enzyme, a ligase, (EC 6.5.1.1) that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond. It plays a role in repairing single-strand breaks in duplex DNA in living organisms, but some forms (such as DNA ligase IV) may specifically repair double-strand breaks (i.e. a ...

Agarose gel electrophoresis is a method of gel electrophoresis used in biochemistry, molecular biology, genetics, and clinical chemistry to separate a mixed population of DNA or proteins in a matrix of agarose. The proteins may be separated by charge and/or size (isoelectric focusing agarose electrophoresis is essentially size independent), and the DNA and RNA fragments by length ...