- Slides: 12
DNA Structure DNA consists of two strands that are arranged into a ladder-like structure called a Double Helix. A molecule of DNA is made up of millions of monomers called Nucleotides. Each nucleotide consists of: 1. Phosphate group 2. Pentose sugar 3. Nitrogenous base
Nucleotides Phosphate Nitrogenous Base Pentose Sugar
The phosphate and sugar form the backbone of the DNA molecule, whereas the bases form the “rungs”. There are four types of nitrogenous bases.
Nucleotides A Adenine C Cytosine T Thymine G Guanine
Chargraff’s Rule: Each base will only bond with one other specific base. This is called complementary base pairing. Adenine (A) Thymine (T) Form a base pair. Cytosine (C) Guanine (G) Form a base pair.
Thymine and Cytosine are pyrimidines Thymine and cytosine each have one ring of carbon and nitrogen atoms. N O O C C C N N C C Thymine O C C N C Cytosine 9
Adenine and Guanine are purines Adenine and guanine each have two rings of carbon and nitrogen atoms. N N C Adenine N C C N O N N C C C Guanine C N N C 10
DNA Structure A gene is a section of DNA that codes for a protein. Each unique gene has a unique sequence of bases. This unique sequence of bases will code for the production of a unique protein. It is these proteins and combination of proteins that give us a unique phenotype.
DNA Gene Protein Trait