Alleles are slightly different molecular forms of the same gene, which are shuffled during meiosis. Crossing over between homologous chromosomes results in new combinations of alleles on the chromosomes. A chromosome's structure may change due to deletion, duplication, inversion, or translocation. B. Autosomes and Sex Chromosomes 1. There are two kinds of chromosomes in human cells.
Sex chromosomes determine gender.
Human females have two X chromosomes. Males have one X and one Y. C. Karyotype Analysis 1. Chromosomes are visualized in a lab preparation called a karyotype. The Y chromosome carries a maledetermining gene which leads to formation of the testes. C. Absence of the male gene in females results in formation of ovaries.