Download Lecture 1a

Nucleic acids are built up from nucleotides as
building blocks
Lecture 1a
Lehninger Principles of
Biochemistry
Chapter 8 sections 1 &2
Nucleotides and Nucleic Acids
Copyright © 2004 by Worth Publishers
Know the molecular
structure of a nucleotide
Know the general structural differences between pyrimidine
and purine bases. Know the numbering system. The pentose
is attached at which N?
Ribose or
deoxyribose?
1
Know the structure of adenine. Differentiate it from guanine.
Only β-D-ribofuranose is present in RNA and DNA
Recognize the various pyrimidines. It takes one reaction to
convert C to U but 2 rxns to go from C to T
Variability in C2 and C3. The rest are planar.
2
Distinguish between nucleotides and nucleosides. Know
abbreviations and terms used.
3
RNA and DNA share: adenosine, cytidine, guanidine.
RNA uses uracil while DNA uses thymidine
4
Note: both DNA and
RNA strands have a
“polarity”. Direction is:
5’ -> 3’ ends.
Note: phosphodiester
linkage.
What’s main structural
difference between RNA
and DNA?
5
Tautomers of Uracil: Lactam is most common form
The base rings absorb UV radiation. Most other biomolecules
do not. (aromatic side chains of amino acids do). Changes in
absorbance at these λ’s can be used to monitor state of DNA.
Abbreviated way to write a deoxyribonucleic acid strand with
sequence 5’-ACGTA-3’
DNA double helix (Watson-Crick; B-DNA). Note the
dimensions.
6
Historic expts: Avery, Mcleod, McCarty Experiment.
Understand what it shows.
7
Hershey-Chase
Experiment
Understand what it
shows and why.
8
X-ray diffraction data by Rosalind Franklin from DNA
fibers suggested helical structure.
Know the dimensions and general structural properties.
Implications.
9
Complementary DNA
double strand (double helix)
follows Watson-Crick rules:
A=T and G-=C
Strands are antiparallel.
10