DNA, RNA, Proteins

Nucleic Acids: “Information Molecules” DNA – Sugar Deoxyribose – Nitrogenous Bases Adenine Guanine Cytosine Thymine RNA – Sugar Ribose – Nitrogenous Bases Adenine Guanine Cytosine Uracil

Purines: 2 Rings

Pyrimidines: 1 Ring

Chargaff’s Rules T – A -2 Hydrogen Bonds C – G -3 Hydrogen Bonds

DNA  DNA Replication

DNA Replication

Origin of Replication Site where replication begins Where nucleotide add = Replication Fork Prokaryotes have a single starting spot Eukaryotes: have multiple starting spots

DNA Polymerase Creates DNA molecules by assembling nucleotides It is an enzyme DNA Polymerase I: removes RNA primers and replaces them with DNA bases by adding to the 3’ end of the previous fragment DNA Polymerase III: adds nucleotides in the 5’  3’ direction

Leading Strand Runs 3’  5’ Copies towards the replication fork Primase adds RNA primer to start chain – One primase for the entire strand

Lagging Strand Runs 5’  3’ Copies away from the replication fork Primase: adds RNA primers at various spots as fork opens Short segments = Okasaki fragments

RNA Primase? This is an enzyme that attaches to DNA in order for other enzymes to come and replicate DNA Once the chain replicates, the RNA primase that has bonded to the DNA strand is removed by an exonuclease DNA Polymerase I: replicates the DNA area where the RNA Primase once was located

IMPORTANT The very last section when the primer is removed from the lagging strand The DNA that replicated is now shorter Therefore, the code shortens with each replication