Module 5—The Molecular Basis of Inheritance Flashcards
Friedrich Miescher
accidentally isolated DNA for the first time
Albrecht Kossel
discovered 4 nitrogenous bases
Phoebus Levene
tetranucleotide hypothesis - incorrect belief that the pattern of bases repeated, making DNA unlikely to be the genetic information
Griffith experiment
first demonstration of heredity by something abiotic (DNA from dead cells)
combination of dead pathogenic cells with live harmless cells yielded pathogenic cells (“transformation”)
Avery, Macleod & McCarty
showed DNA to be the molecule assimilated into a “transformed” cell
destroying DNA prevented transference, but destroying RNA & protein did not
Hershey & Chase
showed that DNA is the genetic material
radiolabelled DNA and protein of phage T2; labels showed DNA in E. coli, but not protein
radiolabelling of phage protein
radioactive sulfur
radiolabelling of phage DNA
radioactive phosphorus
deoxyribose vs ribose
ribose has OH groups at 2’ and 3’
deoxyribose has H at 2’ position instead of OH
purines
structure
2 rings
adenine & guanine
pyrimidines
structure
1 ring
cytosine, thymine, uracil
Chargaff
found that base composition of DNA varies between species, but all species have equal ratios of A to T, and C to G
Franklin & Wilkins
produced x-ray crystallography images of DNA helical pattern
Watson & Crick
deduced structure of DNA:
- double helix structure
- double strand
- complementary base pairing (only A + T and C + G provided uniform width)
- antiparallel backbones
3 forms of DNA
A form
B form
Z form
most important/normal form of DNA
B form
2 areas of DNA where base pairs are accessible
major & minor grooves
diameter of DNA
2 nm
each base is ___ nm apart
3.4
DNA makes a complete turn every ___ bases, or every ____ nm
10
34
dehydration of DNA produces…
A form
no grooves; tighly wound
tension on DNA produces…
Z form
left handed
transient