BIO1011 Lecture Notes - Lecture 11: Phosphodiester Bond, Nucleic Acid Double Helix, Dna Profiling
Lecture 11 - molecular genetics
Applications of DNA technology
● DNA profiling
● Transgenic organisms
● Medicine
DNA as genetic material
● Discovered through the Hershey and Chase’s blender experiment
DNA structure
● Polymer of nucleotides
○ Each containing nitrogenous base, deoxyribose sugar and phosphate
‘backbone’
○ Pyrimidines: smaller, has 1 ring - this is thymine and cytosine
○ Purines: wider, has 2 rings - this is adenine and guanine
● Phosphodiester bond between phosphate and sugar
● Covalent bond between nitrogenous base and sugar
● Discovered through the Watson and Crick theory based on the Wilkins and
Franklin crystallography experiment and the Chargaff’s rule
Double helix
● DNA is double stranded and helical in shape
● Bases face inwards and form pairs
○ 10 base pairs/full turn of helix
● 5’ and 3’ ends
○ Antiparallel
● A pairs with T - 2H bonds
● C pairs with G - 3H bonds
● DNA replication is semiconservative
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Document Summary
Discovered through the hershey and chase"s blender experiment. Each containing nitrogenous base, deoxyribose sugar and phosphate. Pyrimidines: smaller, has 1 ring - this is thymine and cytosine. Purines: wider, has 2 rings - this is adenine and guanine. Covalent bond between nitrogenous base and sugar. Discovered through the watson and crick theory based on the wilkins and. Dna is double stranded and helical in shape. A pairs with t - 2h bonds. C pairs with g - 3h bonds. Dna is copied into rna (mrna specifically) where t is replaced by u (uracil) Rna is single-stranded and has a ribose sugar, not deoxyribose sugar. Polypeptides are encoded in the mrna through triplet codes that are non-overlapping (each 3 base sets are called codons) There are 64 alternatives of codons that code for 20 amino acids. Degenerative coding: some codons code for the same amino acids/signals. Genetic code is universal so genes from one organism can work in others.