Developmental Psychology

Achieve Test Prep: Developmental Psychology

Chapter 3: Genetics, Prenatal Development, and Childbirth

Overview: This chapter starts the beginning of the developmental cycle. The foundation for an introduction to genetics will be established. Particular genetic diseases which affect development will also be discussed. Further in the chapter, the fertilization of an egg and the development into a fetus, as well as childbirth, are examined. Most of these concepts are medically based, easing students’ understanding. Objectives: By the end of this chapter, you should be able to recognize, understand, and explain: • Basic concepts of genetics and the genetic code • Genetic and chromosomal abnormalities • Stages of prenatal development • Teratogens • Steps of the birthing process Concepts of Genetics : Development begins with gametes , or sex cells. The male gamete is sperm and the female gamete is an egg. When gametes combine, their genetic material combines to form a zygote. The zygote begins dividing from one cell into two, and so on. Genetic material of all cells is contained within chromosomes , which are housed within the nucleus. Somatic cells , or body cells, contain 23 pairs of chromosomes. There are 46 total chromosomes. Half of all chromosomes come from the mother and the other half come from the father. Genetic information is transmitted and carried by deoxyribonucleic acid , or DNA. All DNA contains the sugar deoxyribose, a phosphate group, and four bases: adenine (A), thymine (T), guanine (G), and cytosine (C). Bases are organized into pairs: adenine with thymine and guanine with cytosine. The basic unit of hereditary information is a gene . Genes make up the individual segments of chromosomes. Humans have approximately 100,000 genes. Each gene has specific DNA which carries the code from parent to child. There are two special chromosomes called sex chromosomes : X and Y chromosomes. The sex chromosomes are the twenty-third pair of human chromosome. Females have two X chromosomes (XX), while males only have one X chromosome and one Y chromosome (XY). An individual’s genetic makeup is comprised of two different

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