DNA basics

de•ox•y•ri•bo•nu•cle•ic ac•id (DNA)

Interesting DNA facts & basics:

  • DNA is the blueprint of life. Our living nucleic acids (DNA and RNA) direct all of life’s processes. A human has 23 pairs of chromosomes (46 total chromosomes), a canine has 38 pairs and a feline has 19 pairs. All but one pair are autosomes and one pair are sex chromosomes. Females have an XX and males have an XY combination. These chromosome pairs are found in every cell, with one chromosomal DNA copy coming from each parent – whether from a human, animal or plant.

  • 99.9% of the DNA in all humans is identical. It is the tiny difference that allows us to be individuals. DNA has a half-life estimated at 521 years. This means that the oldest organism that could be cloned could not be more than 2 million years old.

  • If we unraveled the entire DNA in a human, it would stretch 10 billion miles. That would be three times the distance from Earth to Pluto.

  • DNA occurs in anti-parallel strands (one strand in the 5’ to 3’ direction, the other opposite this). Chemical bonds keep the sugar-phosphate chain together, while hydrogen bonds keep the complementary strands intact.

  • DNA is made of two linked strands that wind around each other to resemble a twisted ladder — a shape known as a double helix. Each strand has a backbone made of alternating sugar (deoxyribose) and phosphate groups. Attached to each sugar is one of four nucleotide bases: adenine (A), cytosine (C), guanine (G) or thymine (T). One strand couldn’t exist without the other. If the sequence of one strand is known the complementary strand must adhere to complement base pairing (A=T and G=C) so the other strand is also known.

  • DNA is found in a specialized and enclosed part of our cells called the nucleus (plural: nuclei). Most cells in the human body contain a nucleus. Red blood cells have no nuclei and no DNA. This is an adaptation which allows them to carry more oxygen molecules to various parts of the body.