DNA FAQ

DNA is the gossamer thread from which the tapestry of life is woven.

Q. What does "DNA" stand for?
A. DeoxyriboNucleic Acid

Q. Where is DNA found?
A. All living things have DNA as their genetic material. So DNA is found in every kind of cell.

Q. What is DNA?
A. DNA is an information molecule. It contains four different building blocks strung together in a long chain. These building blocks, which are really letters in the genetic language, are called bases and are abbreviated G, A, T, and C. A DNA molecule consists of two partner chains wound around each other and held together by complementary pairs of bases (G pairs with C and A pairs with T) to make the famous double helix. The order of the bases on the DNA determines what proteins will be made in cells and when they will be made.

Q. What is a chromosome?
A. A chromosome is a single, long molecule of DNA. It is usually coated with and coiled around protein molecules. A single chromosome can contain thousands of genes. Humans have 46 chromosomes, comprising 23 pairs. You have inherited one member of each pair from your mother and one member of each pair from your father. One pair of chromosomes determines gender. In females these chromosomes are both "X" chromosomes, one from each parent. Males, on the other hand, have an X chromosome from Mom and a Y chromosome from Dad.

Q. What is a gene?
A. A gene is a segment of a DNA molecule that contains all of the information necessary to build one product (usually a protein).

Q. What does it mean to "sequence" DNA?
A. The DNA sequence is simply the order of the bases (Gs, Cs, As, and Ts) in a DNA strand. This represents the information content, just as the order of letters in this sentence gives it meaning.

Q. What is a genome?
A. A genome is the complete set of genetic information (i.e., DNA sequence) for a particular organism. This is the instruction manual for living things.

Q. What is the Human Genome Project?
A. The Human Genome Project is large, cooperative effort to sequence all of the human genome, find all of the genes, improve technologies for DNA sequencing and genome analysis, store the DNA data and make it accessible, and assess the ethical, legal, and societal issues associated with this information.

Q. What is a mutation?
A. A mutation is an alteration in the DNA, often the exchange of one or more bases for others.

Q. Are all mutations harmful?
A. Many mutations change the information content of a gene in a way that results in the construction of a faulty protein (e.g., cystic fibrosis, sickle cell anemia), but some mutations are harmless, and occasionally a mutation can even be beneficial if it results in a "better" protein.

Q. What is a clone?
A. Well, that depends. In general, clones are genetically identical, as for example in the case of identical human twins or plants grown from cuttings. The term is now often applied to many different levels of genetic identity: DNA molecules, cells, and whole organisms. "Molecular Cloning" refers to making multiple copies of DNA fragments in order to analyze and characterize them.