Biology 1201A Chapter Notes - Chapter 11: Testis Determining Factor, Karyotype, Reciprocal Cross
15 Jul 2015
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11. 1 genetic linkage & recombination: linked genes: genes on same chromosome - > linkage. 11. 2 sex-linked genes: sex-linked genes: inherited differently in males & females, on same chromosome, autosomes: other than sex chromosomes, same patterns of inheritance in males & females. 11. 2a) females=xx, males=xy in humans & fruit flies: females=homologous xx pair, males=xy pair, ex. sperm carrying x chromosome fertilizes w/ x-bearing egg cell - > xx. 11. 2c) sex-linked genes were first discovered in drosophilia: reciprocal cross: phenotypes were switched b/w parents, result: shows distinctive pattern in phenotypic ratio for reciprocal crosses in which genes involved is on x chromosome. 4: barr body: inactive, condensed x chromosome can be seen within nucleus in cells of females as dense mass of chromatin. 11. 3 chromosomal alterations that affect inheritance: alterations caused by radiation, certain chemicals, enzymes encoded in infecting viruses, fragments - > lost or reattach, changes in chromosome # causes genetic differences, lead to disability.
