The highest or uppermost part of something, often referring to the position or location of an object.

An enzyme that alters the supercoiling of DNA by inducing transient breaks in the DNA molecule to relieve torsional strain.

Molecules that have the same molecular formula but differ in their connectivity or spatial arrangement of atoms.

A unit of pressure equal to 1/760th of an atmosphere, used in measuring pressure in gas systems.

A cell that has the ability to differentiate into any type of cell in an organism, including all the cell…

Referring to a substance that is harmful or poisonous to living organisms.

Hazardous materials that are dangerous to living organisms, often produced as a byproduct of industrial, chemical, or biological processes.

The degree to which a substance can damage an organism or cause harmful effects when absorbed, ingested, or otherwise encountered.

The branch of science that studies the harmful effects of substances on living organisms and the environment.

A harmful biological substance produced by organisms, such as bacteria, fungi, or plants, that causes damage to tissues or organs.