DNA Structure: The Molecule of Heredity
Understanding DNA
What DNA Is
DNA stands for deoxyribonucleic acid. It is the molecule that stores hereditary information in almost all living organisms.
DNA Building Blocks
DNA is made of nucleotides. Each nucleotide contains a sugar, a phosphate group, and one nitrogenous base. The four DNA bases are adenine, thymine, cytosine, and guanine.
The Double Helix
DNA is shaped like a twisted ladder called a double helix. The sugar-phosphate backbone forms the sides, and base pairs form the rungs. Adenine pairs with thymine, and cytosine pairs with guanine.
DNA Facts
Which base pairs with adenine in DNA?
In DNA, adenine pairs with thymine.
Correct answer: Thymine
What are the three parts of a DNA nucleotide?
These three parts make up each repeating unit of DNA.
Correct answer: A sugar, a phosphate group, and a nitrogenous base.
What is the overall shape of DNA often called?
DNA is commonly described as a double helix.
Correct answer: A double helix