NUCLEIC ACIDS

Comparison of	Protein       vs.	Nucleic Acid
Monomeric Unit	amino acid	nucleotide
Primary Structure	amino acid sequence	base sequence
Secondary Structure	H-bonding along backbone	H-bonding of bases
Backbone	N-C-C-N-C-C	sugar-phosphate-sugar-phosphate
Linking bond	peptide (amide)	phosphate ester
Reading Direction	N ----- > C	5' ----- > 3'

Types of Nucleic Acid	Bases	Sugar	# nucleotides per molecule	Structure	Use
DNA	A T G C	2-deoxyribose	2-3 x 108	Double Helix structure first explained by Watson & Crick AT and GC base pairing	genetic info storage
mRNA	A U G C	ribose	300-9000	long filament structure	carry info nucleus ribosome
rRNA	A U G C	ribose	100-4000	two spherical subunits	site of protein synthesis
tRNA	A U G C	ribose	70-90	twisted cloverleaf structure	transport amino acids ribosomes

Process	Definition	Location	Enzymes involved	Special notes
Replication	copying of DNA	nucleus	Unwindase, DNA polymerase, DNA Ligase	Okazaki fragments
Transcription	mRNA synthesis	nucleus	RNA polymerase
Translation	protein synthesis	ribosomes	peptidyl synthetase, transferase

Translation involves the following steps:
1) activation amino acid reacts with ATP and then attaches to tRNA
2) initiation tRNA carrying met binds to 40S, 60S binds
3) elongation peptide chain forms at P site, new amino acids arrive at A site, translocation
4) termination stop codon encountered; protein and mRNA detach from ribosome

Genetic Code:
1) universal
2) degenerate
3) precise
4) initiation (AUG)
5) termination (UAG,UGA,UAA)

Codon: triplet of bases on mRNA
Anticodon: triplet of bases on tRNA
Mutations: substitutions, additions, deletions

Genetic Diseases: albinism childhood diabetes phenylketonuria (PKU) dwarfism galactosemia sickle cell anemia cystic fibrosis hemophilia Tay-Sachs, Gauchers, etc

Control of Protein Synthesis
1) Ribonuclease: hydrolyzes mRNA
2) Induction: turning "on" of gene
3) Repression: turning "off" of gene by repressor that blocks operator site

Viruses - protein coat + nucleic acid
DNA virus
RNA virus