DNA Structure DNA Structure 2 molecules arranged into

DNA Structure

DNA Structure 2 molecules arranged into a ladder-like structure called a Double Helix. A molecule of DNA is made up of millions of tiny subunits called Nucleotides. Each nucleotide consists of: 1. Phosphate group 2. Sugar 3. Nitrogenous base (A, T, C, or G)

Nucleotides Phosphate Nitrogenous Base Sugar

Nucleotides Phosphate and sugar form the backbone of the DNA molecule, whereas the bases form the “rungs”.

The 4 Nucleotides A Adenine C Cytosine T Thymine G Guanine

Each base bonds with only 1 other specific base. Adenine (A) Thymine (T) Form a base pair. Cytosine (C) Guanine (G) Form a base pair.

DNA base pairing rules

DNA Structure Because of these rules, the order of the bases on one strand will determine the order of the bases on the other strand. This is called complementary base pairing

A T C G T A C G A T G C T A

DNA Structure To “read” DNA’s genetic code, we look at the sequence of bases. The bases are arranged in triplets called codons. AGG-CTC-AAG-TCC-TAG TCC-GAG-TTC-AGG-ATC

DNA Structure Gene = section of DNA that codes for a protein. Each gene has a specific sequence of bases. This unique sequence of bases will code for the production of a unique protein.

DNA Gene Protein Trait These proteins may produce a unique physical trait = phenotype.