BIOLOGY 1A03 Lecture Notes - Synapsis, Webbed Neck, Colchicine
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BIOLOGY 1A03 Full Course Notes
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During sexual reproduction, a male reproductive cell (sperm) and a female reproductive cell (egg), unite to form a new individual. Process of uniting sperm and egg is called fertilization. Number of chromosomes is constant from cell to cell within a multicellular organism. Chromosome number is also the same in the parent and daughter cells of mitosis. During the formation of gametes, haploid reproductive cells that have one set of chromosomes such as sperm and eggs, there must be a distinctive type of cell division that leads to a reduction in chromosome number. Meiosis is nuclear division that leads to halving of chromosome number. Chromosomes are composed of dna and proteins and carry genes. Sex chromosomes determine the sex of an individual. In humans, there are 24 chromosomes per cell, 12 pairs. Two types of sex chromosomes exist in humans , x and y. Two chromosomes of each type are homologous chromosomes.