J�

Unit 10 : DNA Structure & Replication

structure of a nucleotide

  1. phosphate group

  2. 5 C sugar (dna-deoxyribose, RNA-ribose)

  3. nitrogenous base (dna: A,T,G,C rna: A,U,G,C)

differences between dna and rna

  1. 5 C sugar: dna-deoxyribose; rna-ribose

  2. DNA-double stranded; RNA-single stranded

  3. DNA-thymine; RNA-uracil

4 dna bases and 4 rna bases

  • DNA: adenine, thymine, cytosine, guanine

  • RNA: adenine, uracil, cytosine, guanine

base pairing rules for DNA and RNA

  • DNA: adenine bonds to thymine; cytosine bonds to guanine

  • RNA: adenine bonds to uracil; cytosine bonds to guanine

chargaff’s rule

  • in a given sample of DNA, the amount of A=T and C=G

purines vs. pyrimidines

  • purines: double ring structure, adenine and guanine

  • pyrimidines: single ring structure, cytosine and thymine (also uracil in rna)

    • purines always bond to pyrimidines

rosalind franklin

  • used x-ray crystallography to determine the structure of dna

watson and crick

  • credited with discovering the structure of dna

structure of dna

  • sugar phosphate backbone; nitrogen bases form the “rungs”

  • all the bonds are covalent EXCEPT the hydrogen bonds holding the nitrogen bases together in the center

where replication occurs

  • the nucleus

template for replication

  • dna (both strands)

enzyme required for replication

  • dna polymerase (main enzyme; polymerizes dna nucleotides and proofreads)

  • helicase (unwinds dna double helix), primase (makes an rna primer)

final product of replication

  • exact copy of dna

error rate of replication

  • 1 in 10,000,000,000 bases

definitions

  • helix: spiral

  • complementary base pairs: in dna, A bonds with T and C bonds with G

  • replication: copying dna

  • semi-conservative replication: at the end of replicatIon, each new DNA strand is made up of two strands; one is an old, template strand and one is a new strand

  • mutagen: anything that causes a mutation (example: UV light, some chemicals, radiation)