Biology 2581B Lecture Notes - Lecture 13: Polytene Chromosome, Chromosomal Translocation, Loop Jump
Mutations that we have talked about can also occur in a larger scale on a chromosomal scale. At the sequence level many similarities: same types of genes, same types of nucleotide sequences, obviously not entirely identical. 20 mouse vs. 23 human chromosomes (including sex: banding patterns are not similar, lengths are different for the different chromosomes. Same identify, order, orientation of transcription are all almost the same. Colinearity : the parallel between sequence of nucleotides in a gene to the order of amino acids in a polypeptide. We often think it is negative but it is not. Then recombination events: segments of different groups get close together as recombination occurs, adjacent segments get exchanged and realigned - loss of some segments. Eventually due to recombination the gene gets coded into one single antibody. If there is a lack of diversity in antibodies it can lead to a shift in the formation of t and.