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Lehninger Principles ofBiochemistry

Chapter 8 sections 1 &2Nucleotides and Nucleic Acids

Copyright © 2004 by Worth Publishers

Lecture 1a

Nucleic acids are built up from nucleotides asbuilding blocks

Know the molecularstructure of a nucleotide

Ribose ordeoxyribose?

Know the general structural differences between pyrimidineand purine bases. Know the numbering system. The pentoseis attached at which N?

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Know the structure of adenine. Differentiate it from guanine. Recognize the various pyrimidines. It takes one reaction toconvert C to U but 2 rxns to go from C to T

Only β-D-ribofuranose is present in RNA and DNAVariability in C2 and C3. The rest are planar.

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Distinguish between nucleotides and nucleosides. Knowabbreviations and terms used.

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RNA and DNA share: adenosine, cytidine, guanidine.

RNA uses uracil while DNA uses thymidine

5

Note: both DNA andRNA strands have a“polarity”. Direction is:5’ -> 3’ ends.

Note: phosphodiesterlinkage.

What’s main structuraldifference between RNAand DNA?

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Tautomers of Uracil: Lactam is most common form Abbreviated way to write a deoxyribonucleic acid strand withsequence 5’-ACGTA-3’

The base rings absorb UV radiation. Most other biomoleculesdo not. (aromatic side chains of amino acids do). Changes inabsorbance at these λ’s can be used to monitor state of DNA.

DNA double helix (Watson-Crick; B-DNA). Note thedimensions.

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Historic expts: Avery, Mcleod, McCarty Experiment.Understand what it shows.

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Hershey-ChaseExperiment

Understand what itshows and why.

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X-ray diffraction data by Rosalind Franklin from DNAfibers suggested helical structure.

Know the dimensions and general structural properties.Implications.

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Complementary DNAdouble strand (double helix)follows Watson-Crick rules:

A=T and G-=C

Strands are antiparallel.