Lecture 12

• allosteric model

  rna pol II is destabilized and dissociates from DNA

  may be caused by the release of elongation factors or binding of termination factors
• chloroplasts inherited only from mother

  in mirabilis jalapa, certain mutations resulted in white or variegated leaves, each leaf was only inherited from the mom
• hydrophilic amino acids

  likely to be on surface of protein

  ser, thr, asn, gln, asp, glu, his, lys, arg
• proteins of 2+ polypeptides have quaternary structure

  protein subunits of alpha and beta sheets together
• modular proteins


  each module has a different function

  some modules are found in two or more different proteins
• alternative splicing 


  pre-mRNA with multiple introns can be spliced in different ways

  this will generate mature mRNAs with different combinations of exons

  different splicing choices occur in different cell types or during different stages of development
• splicing factors inhibition

  inhibit the ability of a spliceosome to recognize a splice site

  exon skipping
• the degree of splicing and alternative splicing varies greatly among different species

  bakers yeast: contains about 6300 genes and 300 encode mRNA that are spliced (few are alternatively spliced)

  humans: 26,000 genes, most encode mRNAs that are spliced (about 70% alternatively spliced)