DNA

DNA

Deoxyribonucleic Acid

• DNA has a double-stranded helix
• Consists of two polynucleotide strands wrapped around each other in a double helix
• DNA has four kinds of nitrogenous bases: Adenine, Thymine, Cytosine, and Guanine
• Hydrogen bonds between bases hold the strands together
• Each base pairs with a complementary partner A with T (joined by 2 hydrogen bonds), and G with C (joined by 3 hydrogen bonds)

Discovery

• First discrovered the double helix structure by James Watson and Francis Crick
  • Fun Fact! Francis Crick and James Watson were on LSD when they saw the double stranded helix
• Worked out the three-dimensional structure of DNA, based on work of Rosalind Franklin
  

• Both DNA and RNA are polymers of nucleotides and are nucleic acids
• Sugar Molecule - deoxyribose (DNA)
• Phosphate Group - phosphorous (P) and oxygen (O)
• Nitrogen Base - A, C, G, T (DNA)

• Starts with the separation of DNA strands
• Then enzymes use each strand as a template
  • DNA Helicase: unwind the helix, breaking the weak hydrogen bonds
  • DNA Primase: mark the start point fro DNa replication
  • DNA Polymerase: build the new strand
  • DNA Ligase: make sure the pieces on the second strand are held together tightly
• Assemble new nucleotides into complementary strands
• Because some of the helical DNA molecule must untwist each, strand of the double helix is oriented in the opposite direction
• DNA Replication Animation