Griffith ANS injected mice with bacteria, discovered concept of transformation
Sia & Dawson ANS repeated Griffith's experiment in vitro, proved that mice had nothing to do
with transformation
Avery, MacLeod, and McCarty ANS used DNase, RNase, and protease to determine that DNA is
the factor in transformation
Hershey and Chase ANS used radioactive isotopes of P and S to determine that DNA is the
genetic material
Frankel-Conrat ANS used RNA and proteins in TMV to determine that RNA is the genetic
material in RNA viruses
purines ANS A & G, double ring
pyrimidines ANS C, T, U, single ring
Watson and Crick ANS discovered double-helix model of DNA
Chargaff ANS T=A, C=G, T+C=A+G
distance between base pairs ANS 3.4 angstroms, 10bp per turn
H bonds between A&T ANS 2 H bonds
H bonds between C&G ANS 3 H bonds
, bonding in double helix ANS H bonds between bp
hydrophobic bonds between adjacent bp
chromatin ANS DNA + histones
1 nucleosome= ANS 1 H1, 2 H2a, 2 H2b, 2 H3, 2 H4
centromeres ANS where spindle fibers attach
telomeres ANS -prevent deoxyribonucleases from degrading ends of DNA
-prevent fusion of ends of DNA strands
-facilitate in replication of ends w/o loss of material
Meselson and Stahl ANS demonstrated semiconservative replication by using heavy isotopes of
N in E.coli; 1st gen was half heavy, 2nd gen was a quarter heavy
Taylor, Woods, and Hughes ANS demonstrated semiconservative replication in eukaryotic cells
by using 3H-thymidine in root tips; used autoradiography to determine radioactivity of chromosomes
John Cairns ANS discovered origin of replication in E.coli
prokaryotic origin of replication ANS -one per chromosome
-245 nt pairs long
-13bp sequence in 3 tandem repeats, A:T rich
-9bp sequence repeated 4 times (TTATNCANA)
origin of replication in yeast ANS ARS; 50bp long and includes ATTTATPuTTTA
eukaryotic origin of replication ANS multiple origins in one molecule