DNA Structure and Function Overview

The connection between complementary base pairs in DNA, formed by weak electrostatic attractions.

A rule that states that in a DNA molecule, the amount of adenine (A) always equals the amount of thymine (T), and the amount of cytosine (C) always equals the amount of guanine (G).

The two strands of a DNA molecule run in opposite directions, with one strand having a 5' end and the other a 3' end.

The process by which a DNA molecule is copied, creating two identical DNA molecules.

An enzyme that unwinds the DNA double helix by breaking the hydrogen bonds between base pairs.

An enzyme that adds new nucleotides to a growing DNA strand during replication, following the base pairing rules.

The process of attaching short DNA fragments to a long strand during replication, after the fragments are produced on the lagging strand.

A type of DNA replication where each new DNA molecule consists of one original strand (from the parent molecule) and one new strand. This ensures that the genetic information is accurately copied.

Friedrich Miescher was the first person to isolate DNA, originally called 'nuclein'.

Oswald Avery, Alfred Hershey, and Martha Chase proved that DNA is responsible for heredity, meaning it transmits genetic information between generations. This was a groundbreaking discovery because it changed the prevailing thought that proteins were responsible.

Chargaff's rules state that the percentages of guanine and cytosine are roughly equal in all organisms. The same is true for adenine and thymine.

Rosalind Franklin's X-ray image of DNA, known as Photo 51, revealed its twisted shape. She discovered the structure of DNA was helical (shaped like a coil) and that the nitrogenous bases were situated near the center of the molecule.

James Watson and Francis Crick used Rosalind Franklin's work (without her permission) to build cardboard and wire models of DNA. They discovered DNA's double helix structure.

DNA is an extremely long molecule composed of nucleotides. Each nucleotide consists of three parts: a 5-carbon sugar (deoxyribose), a phosphate group, and a nitrogenous base.

Purines are a type of nitrogenous base with two rings in their structure, including adenine and guanine. Pyrimidines, like cytosine and thymine, have one ring. Uracil is a pyrimidine found only in RNA.

Chargaff's rules are explained by the complementary base pairing of DNA: Adenine pairs with thymine, and guanine pairs with cytosine. This pairing is held together by hydrogen bonds, forming the double helix structure.