Lecture_9_2011

Lecture_9_2011 - Introduction to Biophysics Lecture 7...

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Introduction to Biophysics Lecture 7 Bioinformatics and analysis of evolution
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The most common shape is a right handed α -helix defined by the repeat length of 3.6 amino acid residues and a rise of 5.4 Å per turn. Thus residues (i+3) and (i+4) are closest to residue (i) in the helix. α -helix looks like spring dipoles H-bonds The side chains project outward
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β -strands: parallel or antiparallel The side chains project alternately up and down α - helix β -strand
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While there is restricted rotation about the peptide bond, there is free rotation about the four bonds to the a-carbon of each residue. Two of these rotations are of particular relevance for the structure of the polypeptide backbone. To fully appreciate these rotations, we must shift our perspective from the peptide-bond centered view to the C α -centered view.
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The human genome is about 3 billion (3,000,000,000) bp long The Human Genome Project (HGP) was initiated by the Department of Energy (DOE) in 1986 and was joined by the National Institutes of Health (NIH) two years later. http://www.ornl.gov/sci/techresources/Human_Genome/home.shtml
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Our “junk DNA” is characterized by long stretches of repeated sequences. Function - unknown Is “junk” is worth the cost of sequencing? Sydney Brenner “we have the surprising result that most of the human genome is junk; junk and not garbage because there is a difference that everybody knows; junk is kept while garbage is thrown away.” The portion of the human genome that codes for gene products is only around 1.5 %. Study evolutionary relationships. Repeats can be dated as to when they first appeared and their fates can be followed as they move from one species to another. The human genome has a higher proportion of these repeats (50 percent) as compared to other.
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The mutation rate in the male germ line is twice that of the female germ line. By examining and dating patterns of DNA repeats, scientists have determined mutation rates for the X and Y chromosomes. One reason for the difference between male and female mutation rates is that the production of sperm involves more cell divisions (and chances for mutations to occur) than does the production of eggs. Another contributing factor is the existence of different DNA repair systems in sperm
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Lecture_9_2011 - Introduction to Biophysics Lecture 7...

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