Chapter 8 Summary - Chapter 8 Summary: Human development is...

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Chapter 8 Summary: Human development is the scientific study of the changes that occur in people as they age from conception to death. Since age cannot be directly manipulated by a researcher, developmental psychologists have had to develop alternative methods to investigate the effects of aging on psychological processes. Three common methods used are longitudinal , cross-sectional , and cross-sequential studies. Longitudinal studies have the advantage of following the same subject across time but are limited due to the amount of time and money required to complete the study and the problem of attrition. Cross- sectional studies are cheaper, faster, and easier to conduct since they gather information from different age groups at one particular period of time; however, results from these studies may be confounded due to individual and history differences. Cross-sequential studies are a combination of longitudinal and cross- sectional techniques and often represent an ideal compromise. One of the biggest debates among developmental psychologists is the question of nature versus nurture . Nature refers to the influence of everything you inherited genetically from your biological parents and nurture refers to the influence your environment has had on your development. More recently, the question of interest has switched from nature versus nurture to the interaction of nature and nurture . Behavioral genetics is the field of science that studies the interactions of nature, or genes, and nurture, or the environment. Genetics is the science of heredity and involves the study of DNA, genes, and chromosomes. DNA (deoxyribonucleic acid) is the smallest unit of the three and are strands of molecules linked together like a twisted ladder. The links are made up of amines and their names are abbreviated with the letters A, T, G, and C. The next largest unit are the genes , which are sections of the ladder containing instructions on how to make a specific protein. One way to think of genes is as individual recipes for proteins. The biggest unit is the chromosomes , which are long strands of DNA twisted together and wound up in coils. The chromosomes are found in the nucleus of all the cells of your body except red blood cells. Humans have a total of 46 chromosomes, 23 from the mother’s egg and 23 from the father’s sperm. Each chromosome from the mother matches a chromosome from the father to form 23 pairs. Both chromosomes in the pair have the same genes (for example, each chromosome contains a gene for hair color). Even though they contain the same gene, the instructions on that gene might be slightly different; for example, one of the genes has the instructions for blonde hair while the other gene contains the instructions for brown hair. The first 22 pairs of chromosomes are called autosomes, and the last pair (the 23 rd ) contains the instructions for determining sex and are called the sex chromosomes. Dominant genes are the genes that are more likely to influence the trait. Recessive genes
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Chapter 8 Summary - Chapter 8 Summary: Human development is...

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