dna, rna, proteins. nucleic acids: information molecules dna sugar deoxyribose nitrogenous bases...
TRANSCRIPT
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 RulesT – A- 2 Hydrogen Bonds
C – G- 3 Hydrogen Bonds
DNA DNA Replication
DNA Replication
https://www.youtube.com/watch?v=27TxKoFU2Nw
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