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Genetics. Conception: ovum and sperm fuse to create zygote Chromosomes: contain all biologically inherited information (DNA) Ovum: 23 chromosomes (mom’s contribution) Sperm: 23 chromosomes (dad’s contribution). Zygote. 46 chromosomes (23 pairs: 23 from mom and 23 from dad)
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Genetics • Conception: ovum and sperm fuse to create zygote • Chromosomes: contain all biologically inherited information (DNA) • Ovum: 23 chromosomes (mom’s contribution) • Sperm: 23 chromosomes (dad’s contribution)
Zygote • 46 chromosomes (23 pairs: 23 from mom and 23 from dad) • 22 pairs are called autosomes • 23rd pair contain the sex chromosomes
Mitosis • Cell division resulting in new diploid cells (46 chromosomes) • Chromosomes replicate, then split into two diploid cells
Mitosis Body Cell 46 Chromosomes Daughter Cell 46 Chromosomes Daughter Cell 46 Chromosomes
Meiosis • Cell division resulting in haploid (23 chromosomes) cells • Creation of gametes (sex cells: ovum and sperm)
Meiosis Germ Cell 46 Chromosomes Gamete 23 Chromosomes Gamete 23 Chromosomes
Polygenic Inheritance • Affected by many genes rather than by a single pair.
Sex-linked Chromosomal Abnormalities • Kleinfelter’s syndrome: XXY • XYY syndrome • Fragile X • XXX • Turner’s syndrome
Non Sex-linked Chromosomal Abnormalities • Down Syndrome (Trisomy 21) • Translocation trisomy • Mosaicism • Nondisjunction during meiosis
Maternal Age – Chromosomal Abnormalities • Age Trisomy 21 rate Other chromosomal rate • 20 1/1667 1/526 • 25 1/1250 1/476 • 30 1/952 1/385 • 35 1/378 1/192 • 40 1/106 1/66 • 45 1/30 1/21
Genetic Disorders • TaySachs (autosomal recessive) • Cystic Fibrosis (autosomal recessive) • Phenylketonuria (PKU) (recessive) • Muscular Dystrophy (dominant)