Exciting Developments in Molecular Biology As seen by an amateur

Dr. Ray Sepeta

DNA sequences of nucleotides A – Adenine C – Cytosine G – Guanine T – Thymine N – any nucleotide base R – A or G Y – C or T - none (gap)

RNA A – Adenine C – Cytosine G – Guanine U - Uracil

Central Dogma DNA RNA Protein transcription translation

Proteins strings of amino acids G – Glycine – Gly A - Alanine – Ala L – Leucine – Leu M – Methionine – Met F - Phenylalanine-Phe W – Tryptophan – Trp K – Lysine – Lys S – Serine – Ser N – Asparagine – Asn D – Aspartic acid – Asp B – Aspartate - Asx P – Proline – pro V – Valine – Val I – Isoleucine – Ile C – Cysteine – Cys Y – Tyrosine – Tyr H – Histidine – His R – Arginine – Arg T – Threonine – Thr Q – Glutamine – Gln E – Glutamic acid – Glu Z – Glutamate - Glx

Genetic Code Middle Base 5’ BaseUCAG3’ Base UphesertyrcysU phesertyrcysC leuserquitquitA leuserquittrpG CleuprohisargU leuprohisargC leuproglnargA leuproglnargG AilethrasnserU ilethrasnserC ilethrlysargA metthrlysargG GvalalaaspglyU valalaaspglyC valalagluglyA valalagluglyG

gene chromosome DNA base pairs RNA Watson and Crick Avery Hershey and Chase proteins amino acids genetic code codon central dogma sequence of DNA that codes for a protein contiguous stretch of DNA, contains many genes double helix of base pairs A, C, T, G A – T, G - C ribosomal, messenger, transfer (U for T) discovered structure DNA discovered transforming principle of DNA blender experiment sequence of amino acids, selected by codons and tRNA for proteins codon => amino acid three base pairs-together see slide

virus bacteria prokaryote eukaryote nucleus cytoplasm exons introns number of genes c.elegans corn insects humans DNA (or RNA) in protein coat cell-metabolizes food to function cell without nucleus cell with a nucleus where mRNA is transcribed from DNA outside nucleus, proteins formed stretches of DNA converted to genes DNA excised, “junk” DNA 19,000 40,000 13,500 27,000

In prokaryotes there is no nucleus so transcription and translation occur almost simultaneously. So there is no time to splice out RNA segments

Among eukaryotes as their complexity increases generally so too does the proportion of their junk DNA that does not code for protein

Arguably the most important advance in biology in decades has been the discovery that RNA molecules can regulate the expression of genes. - Sharp

The failure to recognize the importance of introns may well go down as one of the biggest mistakes in the history of molecular biology

Less than 1.5 % of the human genome encodes for protein.

Either the human genome (and that of other complex organisms) is replete with useless transcription, or these nonprotein-coding RNAs fulfill some unexpected function

Generating complexity is easy, controlling it is not.

Sources Censors of the Genome, Sci. Am, Aug 03 Unseen Genome, Sci. Am, Nov 03 RNAi Revolution, Nature, Jul 04 Hidden Genetic Program, Sci. Am, Oct 04 Alternate Genome, Sci. Am, Apr 05