BIOLOGY CHAPTER 12

THE FOUR NITROGEN BASES

• The four nitrogen bases are Adenine, Guanine, Cytosine, and Thymine.
• Cytosine pairs up with Guanine.
• Adenine pairs up with Thymine.

NUCLEOTIDES

• A nucleotide is made of a sugar deoxyribose, a phosphate, and one of the four nitrogen bases.
• It consists of a phosphate, a sugar deoxyribose, and one of the four nitrogen bases.

DNA

• Another name for the structure of DNA is called a Double Helix.
• The sides of the DNA ladder are made from the alternating deoxyribose and phosphate.
• The rungs of the DNA ladder are made from the pairs of bases(C-G and T-A).

PEOPLE WHO ARE INVOLVED WITH DNA

• Fredrick Griffith made the first major experiment that led to the discovery of DNA.
• Oswald Avery built the first model of the double helix.

DOUBLE HELIX

• Oswald Avery built the first model of the double helix.
• The Helicase unwinds and unzips the double helix.

MORE DNA FACTS

• DNA is replicated when the double helix unwinds and the bases match up.
• Codon is the three base code in DNA.
• A mutation is a natural process that changes a DNA sequence.

RNA

• mRNA is messenger RNA.
• tRNA is transfer RNA.
• rRNA is ribosomal RNA.

RIBOSOMES AND PROTEINS

• Amino acids make up proteins.
• Ribosomal and 25 proteins make up ribosomes.