Nucleic Acids
NUCLEIC ACIDS.............................................................................................................................................. 1
NUCLEIC ACIDS.............................................................................................................................................. 2
NITROGENOUS BASES.............................................................................................................................................2
Structure and Chemistry:................................................................................................................................2
Common pyrimidine bases.............................................................................................................................2
Common purine bases....................................................................................................................................2
Properties of pyrimidines and Purines............................................................................................................2
NUCLEOSIDES........................................................................................................................................................3
Formation:......................................................................................................................................................3
Nucleoside triphosphates:..............................................................................................................................4
NUCLEOTIDES....................................................................................................................................................... 4
Structure:........................................................................................................................................................4
4 common ribonucleotides: (nucleotide with ribose as pentose sugar).........................................................4
Functions:.......................................................................................................................................................4
DNA VS RNA.......................................................................................................................................................4
DIFFERENT TYPE OF NUCLEIC ACIDS..........................................................................................................................5
Ribosomal RNA:..............................................................................................................................................5
Transfer RNA:.................................................................................................................................................5
Messenger RNA:.............................................................................................................................................6
DNA DISCOVERY...................................................................................................................................................6
Chargaff’s rule:...............................................................................................................................................6
DNA Double Helix Summary...........................................................................................................................6
STRUCTURE OF NUCLEIC ACIDS................................................................................................................................6
The ‘canonical‘ base pairs:.............................................................................................................................7
Secondary structure of DNA can be denatured and renatured:.....................................................................7
Melting Curves of DNA:..................................................................................................................................7
Tertiary structure of DNA:..............................................................................................................................7
Structure of Eukaryotic Chromosomes:..........................................................................................................7
Nucleosome structure:....................................................................................................................................7
DNA Compacting:...........................................................................................................................................7
DNA REPLICATION......................................................................................................................................... 9
FEATURES OF DNA REPLICATION..............................................................................................................................9
ENZYMOLOGY OF DNA REPLICATION........................................................................................................................9
DNA POLYMERASE I............................................................................................................................................10
DNA POLYMERASE III..........................................................................................................................................10
MECHANISMS OF REPLICATION IN E. COLI................................................................................................................10
Initiation:......................................................................................................................................................10
Elongation & Termination:...........................................................................................................................10
DNA REPLICATION IN EUKARYOTIC CELLS.................................................................................................................11
DNA REPAIR................................................................................................................................................ 11
Point mutations:...........................................................................................................................................11
Mutations arise due to environmental factors or errors during synthesis:..................................................11
2 Maj forms of spontaneous DNA damage:.................................................................................................11
Point mutations due to base mispairings:....................................................................................................12
ALKYLATING AGENTS............................................................................................................................................12
REPAIR MECHANISMS...........................................................................................................................................12
, Nucleic Acids
Nucleic Acids
- DNA isolated, analyzed, recognized as a unique macromolecule in 1869 by Friedrich
Miescher
- Leukocytes from pus -> pure nuclei -> acid-insoluble, alkali-soluble, high-
phosphorous containing substance “Nuclein” -> Nucleic acid -> now known as DNA
- Information transfer: DNA (Replication) -> RNA (Transcription) -> Protein
(Translation)
Nitrogenous Bases
Structure and Chemistry:
- Aromatic, hydrophobic, Carbon based
- Pyrimidine or purine ring system (2 rings)
- Tautomer’s = structural isomers that can interconvert between different forms
quickly.
o A* (tautomer) – H moves from amino group (imino form); binds with C
o C* (tautomer) – H moves from amino group (imino); binds with A
o T* (tautomer) – H moves create alcohol group (enol); binds with G
o G* (tautomer) - H moves create alcohol group (enol); binds with T
- Common pyrimidine bases
- In tautomeric forms (chem equilibrium of tautomers (different structures based on
pH and temp of solvent) at pH 7
- Cytosine (2-oxy-4-amino pyrimidine)
- Uracil (2-oxy-4-oxy pyrimidine)
- Thymine (2-oxy-4-oxy-5-methyl pyrimidine)
- Common purine bases
- Adenine (6-amino purine)
- Guanine (2-amino-6-oxy purine)
- Properties of pyrimidines and Purines
- Acid dissociation constant (Ka):
o Quantitative measure of the strength of an acid in solution
o Equilibrium constant for chem reaction known as dissociation in context of
acid-base reactions.
o
o HA = generic acid; A- = conjugate base
o Conc of water can be taken as constant and ignored
o
NUCLEIC ACIDS.............................................................................................................................................. 1
NUCLEIC ACIDS.............................................................................................................................................. 2
NITROGENOUS BASES.............................................................................................................................................2
Structure and Chemistry:................................................................................................................................2
Common pyrimidine bases.............................................................................................................................2
Common purine bases....................................................................................................................................2
Properties of pyrimidines and Purines............................................................................................................2
NUCLEOSIDES........................................................................................................................................................3
Formation:......................................................................................................................................................3
Nucleoside triphosphates:..............................................................................................................................4
NUCLEOTIDES....................................................................................................................................................... 4
Structure:........................................................................................................................................................4
4 common ribonucleotides: (nucleotide with ribose as pentose sugar).........................................................4
Functions:.......................................................................................................................................................4
DNA VS RNA.......................................................................................................................................................4
DIFFERENT TYPE OF NUCLEIC ACIDS..........................................................................................................................5
Ribosomal RNA:..............................................................................................................................................5
Transfer RNA:.................................................................................................................................................5
Messenger RNA:.............................................................................................................................................6
DNA DISCOVERY...................................................................................................................................................6
Chargaff’s rule:...............................................................................................................................................6
DNA Double Helix Summary...........................................................................................................................6
STRUCTURE OF NUCLEIC ACIDS................................................................................................................................6
The ‘canonical‘ base pairs:.............................................................................................................................7
Secondary structure of DNA can be denatured and renatured:.....................................................................7
Melting Curves of DNA:..................................................................................................................................7
Tertiary structure of DNA:..............................................................................................................................7
Structure of Eukaryotic Chromosomes:..........................................................................................................7
Nucleosome structure:....................................................................................................................................7
DNA Compacting:...........................................................................................................................................7
DNA REPLICATION......................................................................................................................................... 9
FEATURES OF DNA REPLICATION..............................................................................................................................9
ENZYMOLOGY OF DNA REPLICATION........................................................................................................................9
DNA POLYMERASE I............................................................................................................................................10
DNA POLYMERASE III..........................................................................................................................................10
MECHANISMS OF REPLICATION IN E. COLI................................................................................................................10
Initiation:......................................................................................................................................................10
Elongation & Termination:...........................................................................................................................10
DNA REPLICATION IN EUKARYOTIC CELLS.................................................................................................................11
DNA REPAIR................................................................................................................................................ 11
Point mutations:...........................................................................................................................................11
Mutations arise due to environmental factors or errors during synthesis:..................................................11
2 Maj forms of spontaneous DNA damage:.................................................................................................11
Point mutations due to base mispairings:....................................................................................................12
ALKYLATING AGENTS............................................................................................................................................12
REPAIR MECHANISMS...........................................................................................................................................12
, Nucleic Acids
Nucleic Acids
- DNA isolated, analyzed, recognized as a unique macromolecule in 1869 by Friedrich
Miescher
- Leukocytes from pus -> pure nuclei -> acid-insoluble, alkali-soluble, high-
phosphorous containing substance “Nuclein” -> Nucleic acid -> now known as DNA
- Information transfer: DNA (Replication) -> RNA (Transcription) -> Protein
(Translation)
Nitrogenous Bases
Structure and Chemistry:
- Aromatic, hydrophobic, Carbon based
- Pyrimidine or purine ring system (2 rings)
- Tautomer’s = structural isomers that can interconvert between different forms
quickly.
o A* (tautomer) – H moves from amino group (imino form); binds with C
o C* (tautomer) – H moves from amino group (imino); binds with A
o T* (tautomer) – H moves create alcohol group (enol); binds with G
o G* (tautomer) - H moves create alcohol group (enol); binds with T
- Common pyrimidine bases
- In tautomeric forms (chem equilibrium of tautomers (different structures based on
pH and temp of solvent) at pH 7
- Cytosine (2-oxy-4-amino pyrimidine)
- Uracil (2-oxy-4-oxy pyrimidine)
- Thymine (2-oxy-4-oxy-5-methyl pyrimidine)
- Common purine bases
- Adenine (6-amino purine)
- Guanine (2-amino-6-oxy purine)
- Properties of pyrimidines and Purines
- Acid dissociation constant (Ka):
o Quantitative measure of the strength of an acid in solution
o Equilibrium constant for chem reaction known as dissociation in context of
acid-base reactions.
o
o HA = generic acid; A- = conjugate base
o Conc of water can be taken as constant and ignored
o
