Category: S

Discovered by Italian biologist Ferruchio Ritossa in the 1960s, these molecules are also called heat-shock proteins. Proteins made by many organisms’ (plant, bacteria and mammal) cells when those cells are stressed by environmental conditions such as certain chemicals, pathogens, or heat. When corn/maize {Zea mays L.) is stressed during its growing season by high nighttime…

Complementary single strands of DNA (deoxyribonucleic acid) that protrude from opposite ends of a DNA duplex or from ends of different DNA duplex molecules. They can be generated be staggered cuts in DNA. They are called “sticky” because the exposed single strands can bind (stick) to complementary single strands on another DNA molecule. A hybrid…

One that is unable to reproduce. For example, a bull that is castrated is rendered sterile.  

One that is free of any living organisms or spores. For example, a hypodermic needle that has been sterilized (e.g., by heating it) and is free of living microorganisms is said to be sterile.  

This term refers to the compression that a group (chemical entity) suffers by being too close to its nonbonded neighbors. If an enzyme and a substrate try to come together in order to react, but the substrate has on it a bulky group that disallows close contact between the two (because the group bumps into…

Molecules that have the same structural formula but different spatial arrangements of dissimilar groups (of atoms) bonded to a common atom (in the molecule). Many of the physical and chemical properties of stereoisomers are the same, but there are differences in the crystal structures, in the direction in which they rotate polarized light (which has…

The single stem cell in the bone marrow of a fetus from which every immune system cell in the adult has been derived. The primordial stem cell is stimulated to develop into the mature immune system’s differentiated, specialized cells by interleukin-7.  

A growth factor (glycoprotein hormone) that acts upon stem cells in a wide variety of ways to increase growth, proliferation, and maturity (into red blood cells or white blood cells).  

An enzyme that is naturally produced in oil-seed plants. It plays the central role in determining the ratio of saturated to unsaturated fatty acids (in the vegetable oils produced from such plants). Scientists may be able to eventually genetically engineer this enzyme into commercially important vegetable oil producing plants, to modify the ratio of saturated…

A saturated fatty acid containing eighteen carbon atoms in its molecular “backbone”; which is essentially neutral in effect on coronary heart disease in humans (i.e., doesn’t appreciably increase low-density lipoproteins in the bloodstream). Because of the heart disease neutrality, stearate-containing oils (e.g., high-stearate soybean oil) are an excellent cooking oil choice; with the resistance to…