Developmental Psychology

Chapter 3: Genetics, Prenatal Development, and Childbirth

Overview Now that you have learned a bit about the history and the research/ethical portions of developmental psychology, it’s now time to explore genetics, prenatal development, and childbirth. This is the beginning of the developmental cycle. There will be information pertaining genetic diseases that may affect development, as well as the development of the egg and its development into a fetus. Childbirth is also discussed in this chapter. Learning Objectives At the end of this chapter, you should be able to: • Understand basic concepts of genetics and the genetic code • Explain genetic and chromosomal abnormalities • Describe the different stages of prenatal development • Define and understand what teratogens are • Explain the steps of the birthing process 3.1 Concepts of Genetics Gametes are where we start with development. They are also considered as sex cells. Females have egg gamete and males have sperm gamete. When the male and female gametes come together, this material creates a zygote . Zygotes begins by dividing from one cell into two cells, two cells into 4 cells, etc. All cells contain within chromosomes, and chromosomes are located in the nucleus. Body cells, which are called somatic cells have 23 pairs of chromosomes, totaling 64 chromosomes in the human body. Half of the 64 chromosomes come from the mother and the other half comes from the father. Information regarding genetics is carried by DNA or deoxyribonucleic acid . All DNA cells contain a sugar called deoxyribose, a group of phosphates and four different bases. The first base is adenine , then there is thymine , guanine , and cytosine . These four bases are put into pairs. Adenine is paired up with thymine, while guanine is paired up with cytosine. Hereditary information has a basic united called a gene . Genes are what chromosomes are made up from. They are the individual segments of chromosomes. Individuals are known to have around 100,000 genes. All genes are different and have specific DNA and carries genetic codes from the parent to the child. The 23 rd chromosome is called the sex chromosome . Females have two X chromosomes (XX), while males have one X chromosome and one Y chromosome. There are two types of components that make up a person’s genetic makeup. One is called the genotype and the other is called phenotype . The genotype is what makes up the geneticmakeup, which includes 2 types of genes. • Dominant Genes : Traits/Genes that are always expressed • Recessive Genes : Traits/genes that are not expressed The phenotype component is considered to be the observable trait that can be seen. This includes eye color, hair color and the height of a person. There are some genes that are present in the genotype that are not observable. These unexpressed genes are called carriers . The unexpressed genes can be

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