Biology and Behavior the Role of Animal Research Behavior can be explained using a biopsychological perspective in 4 ways 2 Ontogenetic 3 Evolutionary 1 Physiological describes how a structure or behavior develops relates a behavior to the activity of the brain and other reconstructs the evolutionary history of a structure or organs deals with the machinery of the body ex the chemical reactions that enable hormones to influence brain activity and the routes by which brain activity controls muscle contractions including the influences of genes nutrition experiences and their interactions ex the ability to inhibit impulses develops gradually from infancy through the teenage years reflecting gradual maturation of the frontal parts of the brain behavior examines historical influences of natural selection ex monkeys use tools occasionally and humans evolved elaborations on those abilities that enable us to use tools even better this explanation also calls attention to the features left over from ancestors that serve little or no function in the descendants ex human goose bumps useless for humans to have goose bumps erect hairs because we don t have long enough hair this is trait that was developed by our ancestors and inherited as a mechanism by us to deal with fear describes why a structure or behavior evolved as it did and the advantage of the structure or behavior ex certain animals have an appearance that matches their background enabling them to camouflage themselves from predators ex zone tailed hawks fly among vultures and hold their wings in the same posture as vultures thus allowing them to swoop in on prey that would otherwise flee if they knew their true appearance 4 Functional Animals are used to explore research questions because 1 Similarities to humans the underlying mechanisms of behavior are similar across species and sometimes easier to study in a nonhuman species 2 Humans are naturally curious about animals 3 What we learn about animals sheds light on human evolution 4 Legal or ethical restrictions prevent certain kinds of research on humans Genes Behavior Genes Units of heredity that maintain their structural identity from one They hold the information to build and maintain an organism s cells generation to another and pass traits to offspring Genes come in pairs because they re aligned along chromosomes strands of genes that also come in pairs A gene has been defined as a portion of a chromosome which is composed of the double stranded molecule deoxyribonucleic acid DNA which helps code for proteins o A strand of DNA serves as a template for the synthesis of RNA linked which serves as a template for the synthesis of protein molecules DNA contains 4 bases whose order determines the order of the corresponding bases on the RNA molecule the order of THESE bases in turn determines the order of the amino acids that compose a protein genes genes located on the sex chromosomes X and Y Sex usually linked to the X chromosome sex linked traits are expressed more often in males because males only have 1 X chromosome and need a trait to appear only on that one X chromosome to show it Sex chromosomes but active mainly in only one sex both sexes have the genes but sex hormones activate them in one sex or another genes present in both sexes generally on autosomal genes limited A sex linked gene is on a sex chromosome usually the X chromosome A sex limited gene could be on any chromosome but it is activated by sex hormones and therefore shows its effects only in one sex or the other There are 2 phenomena that alter genetic material 1 Mutation a heritable change in a DNA molecule a change in gene expression due to a change in DNA results in altered amino acid sequencing and thus protein construction changes in gene expression without modification of the DNA sequence typically due to pre natal environmental factors Can 2 Epigenetics be heritable because the proteins that control gene expression are changed even though the genetic code itself is not Certain experimental procedures may be performed in order to differentiate between genetic and environmental influences on behavior Studies using genetically modified animals knockout mice Twin studies either monozygotic identical twins with same genetic code or dizygotic fraternal twins as genetically similar siblings Adoption studies Gene association studies Homozygous genes on each chromosome are identical Heterozygous genes on each chromosome are different Dominant Gene shows a strong effect in either the homozygous or heterozygous condition Recessive Gene shows it effects only in the homozygous condition Neurons Glial Cells STRUCTURE ORGANELLE FUNCTION Separates the inside of the cell from the outside environment composed of 2 layers of fat molecules that freely flow around one another most chemicals cannot cross the membrane but specific protein channels in the membrane permit a controlled flow of water oxygen potassium calcium chloride and other important chemicals Contains chromosomes Performs metabolic activities providing the energy that the cell requires for other activities require fuel and oxygen to function Sites at which the cell synthesizes new protein molecules A network of thin tubes that transport newly synthesized proteins to other Plasma Membrane Nucleus Mitochondria Ribosomes Endoplasmic Reticulum locations Neurons receive information and transmit it to other cells and contain structures designed to accomplish these tasks o Axons o Dendrites send information may be coated in a myelin sheath so receive information may be equipped w spines to increase surface area information can be transmitted faster spaces between the myelin are called nodes of Ranvier turns chemical end of the axon where electrical action o Presynaptic Terminal Neurons are similar to normal body cells in that they Contain a nucleus containing genetic material Surrounded by a membrane that protects cells Contain organelles that support the life of the cell Types of Neurons NEURON TYPE Motor Sensory Interneuron Intrinsic neuron Types of Glia Cells FUNCTION Receives excitation from other neurons through its dendrites and conducts impulses along its axon to a muscle Specialized at one end to be highly sensitive to a particular type of stimulation such as light touch or sound conducts touch information from the skin to the spinal cord Connects sensory to motor neurons within a single structure Neurons can either be afferent or efferent an afferent axon
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