Genetics: Analysis of Genes and Genomes: Keyword Hot Links for chapter 10

A sequence logo is a graphical representation of a set of nucleotide sequences that are binding sites for proteins or other macromolecules. The logo uses letters of differing size to display the relative frequencies of alternative bases at each position in the sequence, so that information about variation in the sequence motif is not lost as it is in a conventional consensus sequence. This keyword site contains logos for many sequence motifs that are important in gene expression. Check out the logos for yeast TATA boxes as well as the splice donor and splice acceptor sites in human RNA processing to judge how strongly the "consensus sequences" are conserved.

The keyword structures will link you to a site offering a three-dimensional display of over 200,000 small biological molecules, including the common amino acids. Using the mouse, you can tilt and rotate the structures to analyze the spatial relationships among the atoms. At the is keyword site you can browse through the amino acids to gain an appreciation of their relative sizes and shapes, and you can examine a peptide bond by selecting alanine-alanine in the category biomolecules. (The comparisons are facilitated if your computer system can support two browser windows running side by side.)

The gene CCA1 in yeast is critical for the formation of all mature transfer RNA molecules that are able to be charged with the correct amino acid. Search this keyword site for the gene CCA1 to find out what reaction is catalyzed by the gene product, and how this reaction changes the sequence of the tRNA. You may also locate the gene on the genetic map and retrieve its DNA and amino acid sequence.

Cystic fibrosis is among most common serious inherited human disorders. It results from any of a number of mutations resulting in a defect in the cystic fibrosis transmembrane conductance regulator (CFTR), one of a family of membrane chloride channels. The gene is designated CFTR. The mutant allele of CFTR most frequently encountered in patients is DF508, a deletion of three nucleotides that deletes a phenylalanine at position 508 in the CFTR polypeptide chain. Although the DF508 deletion accounts for about two-thirds of the mutant CFTR alleles in the human population, more than 700 mutant alleles have been described. Most of these are listed at this keyword site. Note the great variety of different types of mutations that have been described: promoter mutation, amino acid replacement, frameshift mutation, splicing defect, deletion, and so forth.