Glossary
Plain-English definitions of the most common terms in cloning, stem-cell, and bioethics writing — with links to the longer explainers.
Bioethics
The study of ethical questions raised by biology and medicine, including questions about cloning, reproductive technology, genetic editing, and the use of human tissue in research.
Clone
An organism, cell, or DNA sequence that is genetically identical or nearly identical to another. In casual speech the word often refers to a duplicate person; in biology it refers to many different things.
DNA (deoxyribonucleic acid)
The molecule that carries the genetic instructions used in the development, functioning, growth, and reproduction of all known organisms.
Embryo
An early stage in the development of a multicellular organism. In humans, the term is used for the period from fertilisation until about the eighth week of pregnancy.
Embryonic stem cells (ESCs)
Pluripotent stem cells derived from early embryos. In research, they are typically obtained from embryos donated from in-vitro fertilisation procedures, under strict ethical and regulatory frameworks.
Epigenetics
The study of chemical modifications to DNA and associated molecules that change how genes are expressed without changing the DNA sequence itself.
Gene
A unit of heredity. A specific stretch of DNA that contains the instructions for a particular function, often the production of a protein.
Gene cloning
The laboratory technique of copying a specific piece of DNA. Routine in modern molecular biology. Has nothing to do with making a copy of a person. See gene cloning vs human cloning.
Genome
The complete set of genetic material in an organism, including all of its genes and the regions between them.
Germline
Refers to the cells that pass genetic information to the next generation — sperm, eggs, and the cells that produce them. Changes to the germline can be inherited by offspring.
Induced pluripotent stem cells (iPSCs)
Pluripotent stem cells produced by reprogramming adult cells in the laboratory. They do not require an embryo and have become a workhorse of modern regenerative-medicine research.
Mitochondrial DNA
A small amount of DNA found inside mitochondria, the energy-producing structures within cells. In cloning by nuclear transfer, mitochondrial DNA usually comes from the egg donor rather than the nuclear donor.
Nucleus
The structure inside a cell that contains most of its DNA, organised into chromosomes. Nuclear transfer techniques move the nucleus from one cell to another.
Pluripotent
Describes a cell that can give rise to nearly all cell types in the body. Both embryonic stem cells and induced pluripotent stem cells are pluripotent.
Reproductive cloning
The use of nuclear-transfer techniques to produce a living organism genetically very similar to an existing one. Done in animals, not in humans, and broadly prohibited. See reproductive cloning.
Somatic cell
Any body cell that is not a sperm or egg cell. Skin cells, liver cells, and neurons are all somatic cells.
Somatic cell nuclear transfer (SCNT)
A laboratory technique in which the nucleus of a body cell is transferred into an egg cell whose own nucleus has been removed. SCNT underlies both therapeutic and reproductive cloning. See SCNT explained.
Stem cell
An unspecialised cell that can renew itself and give rise to specialised cells. See stem cells and cloning.
Therapeutic cloning
A research technique that uses SCNT to produce early-stage cells whose nuclear DNA matches a donor, typically to derive donor-matched pluripotent stem cells for study. See therapeutic cloning.
Open future
A philosophical idea associated with bioethicist Joel Feinberg: that children have an interest in a future not heavily pre-shaped by the choices of others.
Human dignity
A foundational concept in many ethical and legal frameworks describing the inherent worth of human beings. Different traditions ground the concept differently, but it figures heavily in international cloning declarations.
Definitions on this page are simplified for general readers. For precise legal or medical definitions, consult primary sources from NIH, NHGRI, WHO, UNESCO, and national bioethics committees.