Introduction to Psychology

Introduction to Psychology of 97 The egg cell from the mother and the sperm cell from the father carry within their nuclei the material of heredity, in the form of rod like units called chromosomes. A chromosome is a double stranded and tightly coiled molecule of DNA. All of the information for heredity is encoded in the combinations of four chemical bases - adenine, thymine, guanine, and cytosine - that occur throughout the chromosome. Within each DNA molecule, the sequence of the four letters of the DNA alphabet - A, T, G, C - creates the specific commands for every feature and function of the person. The DNA portion of the chromosome body carries the genes, the biological units of heredity. With the exception of the egg and sperm cells, every cell in the body carries within its nucleus 23 pairs of chromosomes, each containing numerous genes that regulate every aspect of cellular functioning. Every cell nucleus in the body contains the genetic code for the entire body. Genome In 1990, geneticists began the Human Genome Project, a coordinated effort to map DNA, including all the genes, of the human organism. The genetic structure in every one of the 23 chromosome pairs has now been mapped, by methods that allow investigators to literally disassemble the genes in each chromosome and study their specific sequences of bases (A,T,G, and C). The first results of the genome project showed that the human genome consists of approximately 25,000 genes; and the location and structure of more than 80 genes that contribute to hereditary diseases have been identified through gene mapping. Evolution The separate paths of behaviorism and ethology have increasingly converged, reminding us that the environment shapes behavior in two fundamental ways: through species adaptation and through personal adaptation. Our personal adaptation to life’s circumstances occurs through the laws of learning, resulting from our interactions with immediate and past environments. The environment also influences species adaptation. Over the course of evolution, the environmental conditions faced by each species helped shape biology. Theorists proposed that, as the human brain evolved, it acquired capacities that enhanced our ability to learn and solve problems. Evolution is a change over time in the frequency with which particular genes, and the characteristics they produce, occur within an interbreeding population. • Charles Darwin- He was an English naturalist and geologist, best known for his contributions to evolutionary theory. He established that all species of life descended over time from common ancestors. He introduced the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection, in which the struggle for existence has a similar effect as the artificial selection involved in selective breeding. © 2015 Achieve Page 17