PSC 140 Lecture Notes - Lecture 2: Abortion, Stillbirth, Trisomy
Document Summary
46 in all human cells, except sperm & ova which have 23. Chromosome - a threadlike structure made up of genes. Deoxyribonucleic acid (dna) - a long double - stranded molecule that makes up. Genes - the segments on a dna molecule that act as hereditary blueprints for chromosomes the organism"s development. Zygote = single cell produced by joining of sperm & ovum. Mitosis - cell division for all cells except sperm & ovum. Process of replication ( produces exact copies) Produces 2 daughter cells identical to the parent cell. Meiosis - process of cell production for sperm & ova (germ cells ) Cells divide 2x, producing 4 daughter cells. In female, 3 cells disintegrate & 1 becomes ovum. Each sperm & ovum contain 23 chromosomes (half of the original set of chromosomes) Monozygotic twins (mz) - come from the same zygote. Dizygotic twins (dz): - formed by fertilization of 2 separate ova. Chance - 1 out of 250 conceptions.
