2 - Social & Human Sciences Department (SAHSD) Centre...

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PHD 0015 Human Development ONLINE NOTES FOSEE , MULTIMEDIA UNIVERSITY (436821-T) MELAKA CAMPUS, JALAN AYER KEROH LAMA, 75450 MELAKA, MALAYSIA. Tel 606 252 3594 Fax 606 231 8799 URL: http://fosee.mmu.edu.my/~asd/ (SAHSD) Centre for Foundation Studies and Extension Education (FOSEE)
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PHD0015 HUMAN DEVELOPMENT Chapter 2 PHD 0015 Human Development Topic 2 Genetic foundations of development, reproduction, prenatal, birth, and neonatal Introduction (Refer textbook Chapter 3) 1. Reproduction starts when a sperm cell unites with an ovum to form a single new cell called a zygote. 2. Spermatogenesis is the process of sperm production that takes place in the testes of the male after he reaches puberty. At each ejaculation, 200 million to 500 million sperm are released. 3. Ovulation is the process by which the mature ovum separates from the ovarian wall and is released from the ovary. 4. During intercourse, millions of sperm are ejaculated into the vagina, move to the uterus, and up to the fallopian tubes. 5. Fertilization or conception is the process by which sperm and ovum combine to create a zygote, which then becomes a baby. 6. Fertilization is most likely if intercourse occurs on the day of ovulation or during the five days before. Genetic Code 1. Chromosomes carry the hereditary materials called genes that direct the physical changes in the body throughout development. Each body cell, except the sex cells (gametes) contains 23 pairs of chromosomes. 2. Through meiosis process, the sex cells (sperm or ovum) end up with only 23 single chromosomes. 3. When the sperm and ovum unite, the 23 single chromosomes combine in pairs to produce 46 chromosomes in the zygote. 4. Genes are made of molecules called DNA (deoxyribonucleic acid). Each body cell has the same DNA code and genes that direct growth. 5. In the zygote, the twenty-two pairs of chromosomes are called autosomes that are responsible for most aspects of the individual's development. The twenty-third pair is called the sex chromosomes, which determine the gender of the offspring. __________________________________________________________________________________ SRS 2/ 9
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PHD0015 HUMAN DEVELOPMENT Chapter 2 6. Men produce two types of sperm: one with an X chromosome and the other is with a Y chromosome. 7. Women produce ova with only X chromosomes. 8. If a sperm containing a Y chromosome unites with an ovum (Y + X = XY), a boy is conceived. If a sperm containing an X chromosome unites with an ovum (X + X = XX), a girl is conceived. 9. Monozygotic or identical twins are produced from one ovum, which fertilized by one sperm. The cell divides during development to produce two embryos. 10. Dizygotic or fraternal twins are produced when two ova fertilized by two separate
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2 - Social & Human Sciences Department (SAHSD) Centre...

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