bacteria

One of two prokaryotic (no nucleus) domains, the other being the ARCHAEA. Bacteria are microscopic, simple, single-cell organisms. Some bacteria are harmless and often beneficial, playing a major role in the cycling of nutrients in ecosystems via aerobic and anaerobic decomposition (saprophytic), while others are pathogenic, causing disease and even death.

Some species form symbiotic relationships with other organisms, such as legumes, and help them survive in the environment by fixing atmospheric nitrogen. Many different species exist as single cells or colonies, and they fall into four shapes based on the shape of their rigid cell wall: coccal (spherical), bacillary (rod-shaped), spirochetal (spiral/helical or corkscrew), and vibro (comma-shaped). Bacteria are also classified on the basis of oxygen requirement (aerobic vs. anaerobic).

In the laboratory, bacteria are classified as grampositive (blue) or gram-negative (pink) following a laboratory procedure called a Gram’s stain. Gram-negative bacteria, such as those that cause the plague, cholera, typhoid fever, and salmonella, for example, have two outer membranes, which make them more resistant to conventional treatment. They can also easily mutate and transfer these genetic changes to other strains, making them more resistant to antibiotics. Gram-positive bacteria, such as those that cause anthrax and listeriosis, are more rare and are treatable with penicillin but can cause severe damage by either releasing toxic chemicals (e.g., clostridium botulinum) or by penetrating deep into tissue (e.g., streptococci). Bacteria are often called germs.

balanced polymorphism

The maintenance of two or more alleles in a population due to the selective advantage of the heterozygote. A heterozygote is a genotype consisting of two different alleles of a gene for a particular trait (Aa).

Balanced polymorphism is a type of polymorphism where the frequencies of the coexisting forms do not change noticeably over many generations. Polymorphism is a genetic trait controlled by more than one allele, each of which has a frequency of 1 percent or greater in the population gene pool. Polymorphism can also be defined as two or more phenotypes maintained in the same breeding population.

Banting, Frederick Grant (1891–1941) 

Canadian Physician Frederick Grant Banting was born on November 14, 1891, at Alliston, Ontario, Canada, to William Thompson Banting and Margaret Grant. He went to secondary school at Alliston and then to the University of Toronto to study divinity before changing to the study of medicine. In 1916 he took his M.B. degree and joined the Canadian Army Medical Corps and served in France during World War I. In 1918 he was wounded at the battle of Cambrai, and the following year he was awarded the Military Cross for heroism under fire.

In 1922 he was awarded his M.D. degree and was appointed senior demonstrator in medicine at the University of Toronto. In 1923 he was elected to the Banting and Best Chair of Medical Research, which had been endowed by the legislature of the Province of Ontario.

Also in 1922, while working at the University of Toronto in the laboratory of the Scottish physiologist John James Richard MACLEOD, and with the assistance of the Canadian physiologist Charles Best, Banting discovered insulin after extracting it from the pancreas.

The following year he received the Nobel Prize in medicine along with Macleod. Angered that Macleod, rather than Best, had received the Nobel Prize, Banting divided his share of the award equally with Best. It was Canada’s first Nobel Prize. He was knighted in 1934. The word banting was associated with dieting for many years.

In February 1941 he was killed in an air disaster in Newfoundland.