BIOLOGY 1A03 Lecture Notes - Lecture 20: Meiosis, Metaphase, Nondisjunction
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BIOLOGY 1A03 Full Course Notes
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Transmission of genes from one generation to the next, many traits inherited but there is also genetic variation: the two parents give rise to offspring that have unique combinations of genes. The females produce gametes in the similar manner, and yield 1 egg and 3 polar bodies. It allows for the recombination of parental homologous chromosomes and the production of unique and variable gametes. This is done by a synaptonemal complex that forms between homologous chromosomes and holds them together: homologous chromosomes may have different alleles of the same genes at the specific loci for specific genes. In prophase i, crossing over occurs, and the genetic information between the homologous chromosomes is exchanged at the chiasma (or chiasmata if more than one region of crossing over). Centrosome duplication, movement, spindle formation and nuclear breakdown also occurs during prophase i: all homologous chromosomes will pair with each other during synapsis.