Biology 6.3-DNA 3

• Polymers are made up of many units called monomers.
• DNA is a polymer.
• DNA is made up of monomers that are called nucleotides.
• Nucleotides are made up of three parts: phosphate, sugar and a base.
• Every nucleotide has the same phosphate and same sugar.
• The bases in each nucleotide can be one of four bases.
• The bases are Adenine, Thymine, Cytosine and Guanine.
• There are 4 types of nucleotides.
• There is a hydrogen bond between the phosphate of one nucleotide and the sugar of another.
• The phosphate of one nucleotide bonds with the sugar of another, and this process repeats and forms a long chain of nucleotides.
• The long chain of phosphates and sugars is called the backbone of the DNA molecule (sugar-phosphate backbone).
• The bases of the nucleotides pair up and hold the two strands of the double helix together.
• One strand of DNA is made up of a long chain of nucleotides, held together by hydrogen bonds between the phosphate group and the sugar.
• Only complimentary bases pair up.
• Adenine pairs up with Thymine.
• Cytosine pairs up with Guanine.
• Genetic code is a sequence of bases.
• Gene is a particular sequence of bases that code for a particular protein.
• Bases are grouped in threes called triplets, which code for a specific amino acid.
• A long chain of amino acids form a protein.
• Proteins are different sequences of amino acids, and are uniquely shaped, therefore carrying out specific functions.
• The main uses of proteins are in enzymes (biological catalysts to speed up the rate of chemical reactions), hormones (chemical messengers), and structural proteins (strengthen cells and tissues).
• 1. The order of bases controls the order in which amino acids are assembled to produce a particular protein.