BIOL1003 Final: Molecular genetics
What is a chromosome?
• Condensed chromatin ready for cell division
• Nucleic acids and proteins
Virus
Bacteria
Eukaryotes
• Nucleic acids in
protein capsule
• No nucleus
• No cell
• No membrane
• Cell surrounded
by membrane and
capsule
• No nucleus
(nucleic acids
freely in cell)
• Proteins in
membranes and
capsule
• Cell surrounded
by membrane
• Nucleus
surrounded by
membrane
• Nucleic acid and
protein in nucleus
• Proteins in
membranes
• Proteins in
organelles
Griffiths Experiment
• Looking for pneumonia vaccine
• S strain, virulent
• R strain, non virulent
Proposed that cells contained a non living transforming principle that could
transform one cell into another – not sure whether protein or nucleic acid
Avery, MacLeod and McCarthys experiment
• Aimed to identify transforming principle
• Grew large batches of S-strain bacteria
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• Treated cell extracts with:
o Proteinase- transformation still occurs
o Nuclease- no transformation
• Implies DNA is the transforming principle (no one wanted to believe
them)
Hershey- Chase experiment
Therefore, DNA carries genetic information
95: Chargraffs rules
• Composition of DNA varied from one species to
another
• But in every species,
1953: Watson and Crick
• Used X-ray data from Rosalind Franklin and Maurice Wilkins
• Knowledge of chemical composition of DNA
• Built models
• Had no real evidence for their structure
The monomer building blocks of DNA: nucleotide monophosphates
find more resources at oneclass.com
find more resources at oneclass.com
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
What is a chromosome: condensed chromatin ready for cell division, nucleic acids and proteins. Virus: nucleic acids in protein capsule, no nucleus, no (cid:494)cell(cid:495, no membrane. Griffith(cid:495)s experiment: looking for pneumonia vaccine, s strain, virulent, r strain, non virulent. Proposed that cells contained a non living (cid:494)transforming principle(cid:495) that could transform one cell into another not sure whether protein or nucleic acid. Avery, macleod and mccarthy(cid:495)s experiment: aimed to identify transforming principle, grew large batches of s-strain bacteria, treated cell extracts with, proteinase- transformation still occurs, nuclease- no transformation. Implies dna is the transforming principle (no one wanted to believe them) Therefore, dna carries genetic information: composition of dna varied from one species to (cid:883)95(cid:882): chargraff(cid:495)s rules another, but in every species, 1953: watson and crick: used x-ray data from rosalind franklin and maurice wilkins, knowledge of chemical composition of dna, built models, had no real evidence for their structure. The monomer building blocks of dna: nucleotide monophosphates.