ASC 362 Exam 1 fully solved & updated

Animal Genetics - ANSWER-the study of principles of inheritance in animals Animal Breeding - ANSWER-involves the selective breeding of domestic animals with the intention of improving desirable (and heritable) qualities in the next generation Phenotype - ANSWER-the set of observable characteristics of an individual; ex - red, roan, polled, horned Genotype - ANSWER-an individuals collection of genes for one or a few specific traits; ex - BbPP, BBPp Population - ANSWER-refers to a group of individuals, of the same species and location, that can interbreed with each other DNA - ANSWER-genetic information carrier Gene - ANSWER-basic units of heredity that form the link between generations; ex - B,b,a,A Genome - ANSWER-the sum total of an animal's genes; made of up chromosomes Chromosomes - ANSWER-occur in pairs in the nucleus; made up of DNA strands Haploid - ANSWER-a single set of unpaired chromosomes; n Diploid - ANSWER-two complete sets of chromosomes, one from each parent; 2n Locus - ANSWER-denotes the site of a particular gene Allele - ANSWER-different forms of a particular gene Autosome - ANSWER-any chromosome that is not a sex chromosome Sex Chromosome - ANSWER-a chromosome involved with determining the sex of an organism Homozygote - ANSWER-if both genes at the locus are functionally the same; BB or bb Heterozygote - ANSWER-one-locus genotypes contain different genes; Bb Carrier - ANSWER-an organism that has inherited a recessive allele for a genetic trait or mutation but does not show that trait or its symptoms Hemizygous - ANSWER-having only a single copy of a gene with no allelic counterparts Law of Segregation - ANSWER-in the formation of a gamete, the two genes at a locus in the parent cell are separated that each gamete is equally likely to contain either member of the pair Law of Independent Assortment - ANSWER-genes assort independently during meiosis Gametes - ANSWER-the reproductive genes; sperm and egg Meiosis - ANSWER-a mode of cell division in which reproductive cells are created that contain only one member of each pair of chromosomes Zygote - ANSWER-offspring Punnett Square - ANSWER-a two-dimensional grid that is used to determine the offspring obtainable from a mating Dominant - ANSWER-an allele or gene that masks the effect of the recessive allele Recessive - ANSWER-an allele that is masked by the effects of a dominant gene Complete Dominance - ANSWER-expression of the heterozygous genotype is identical to expression of the homozygous dominant phenotype Partial Dominance - ANSWER-expression of the heterozygous genotype is intermediate to the expressions of the homozygous genotypes but more closely resembles expression of the homozygous dominant genotype Incomplete (No) Dominance - ANSWER-the heterozygotes is dissect from and midway between the phenotypes of the homozygous genotypes Co-Dominance - ANSWER-both alleles of a gene pair are fully expressed, neither being dominant or recessive to the other Epistasis - ANSWER-a property of genes at different loci in relation to a particular phenotypic trait Additive Gene Action - ANSWER-effect of one additive gene added to effect of another additive gene, and so on, for all additive genes that influence trait; dominance is absent Sex-Influenced Traits - ANSWER-carried on the autosomes; expression is influenced by the sex of the individual; the same genotype produces a different phenotype depending upon the sex of the animal Sex-Linked Traits - ANSWER-any trait controlled by locus on X chromosome will show relationship with inheritance of sex Sex-Limited Traits - ANSWER-limited to one of the two sexes; autosomal; ex - milk production, semen quality Population Genetics - ANSWER-the study of changes in the frequency of alleles in populations of individuals Gene Frequency (Allelic Frequency) - ANSWER-the promotion of loci carried by individuals with a population that are of a specific type; the relative abundance or rarity of a specific allele in a population Phenotypic Frequency - ANSWER-the proportion of individuals in a population that are in a particular phenotype Genotypic Frequency - ANSWER-the proportion of individuals in a population that posses a particular of genes Simply-Inherited Trait - ANSWER-a genetic trait that is controlled by one or just a few genes Polygenic Trait - ANSWER-genetic traits that are controlled by two or more genes Random Mating - ANSWER-the random mating of individuals is equivalent to the random union of gametes; the situation where each male in a population has an equal opportunity of mating with each female and vice versa Fitness - ANSWER-the ability of the individual and its corresponding phenotype and genotype to contribute offspring to the next generation Inbreeding - ANSWER-the mating of related individuals; increases the frequency of homozygous genotypes Crossbreeding (Outbreeding) - ANSWER-the mating of unrelated individuals, increases heterozygosity Hardy-Weinberg Equilibrium - ANSWER-gene and genotypic frequencies of a large, random mating population will remain constant from generation to generation, and the genotypic frequencies will equal the square of the gene frequencies, in the absence of migration, mutation, and selection Selection - ANSWER-the process that determines which individuals become parents, how many offspring they produce and how long they remain in the breeding population Natural Selection - ANSWER-process whereby animals that are better adapted to their environment and have a higher chance to survive and reproduce more offspring than less adapted animals Artificial Selection - ANSWER-imposed by humans Mutation - ANSWER-nearly always deleterious; small changes Migration - ANSWER-intermixing of 2 or more breeding populations; sudden heritable change in genetic material Nonrandom Mating - ANSWER-allowing animal to breed with select females Genetic (Random) Drift - ANSWER-a change in gene and genotypic frequencies due to chance; inversely proportional to population size; reduces genetic variation Inter Se Mating - ANSWER-mating of animals between or among themselves Fixation - ANSWER-the change in a gene pool from a situation where there exists at least two variants of a particular gene/allele to a situation where only one of the alleles remains Robert Bakewell Leicester Sheep, Longhorn Cattle, Shire Horses Inbreeding and Progeny testing - ANSWER-Who was the 18th century english farmer who used some techniques that have since been determined to be effective tools for genetic improvement? What livestock did he breed? What two techniques did he use? Gregor Mendel - ANSWER-Who was the 19th century priest who bred garden peas and developed basic principles of genetics? Charles Darwin - ANSWER-Who was the 19th century British naturalist who developed the Theory of Natural Selection as an explanatory force for evolution? Dr. Jay L. Lush - ANSWER-Who was the Iowa State scientist who assembled the ideas of population genetics and applied them to genetic improvement of livestock? Robert Bakewell - ANSWER-Who is known as the "Father of Livestock Selection"/"Father of Animal Breeding"? Dr. Jay L. Lush - ANSWER-Who is known as the "Father of Modern Animal Breeding"/"Father of Modern Scientific Breeding"? Humans: 46 Cattle: 60 Chickens: 78 Donkeys: 62 Goats: 60 Horses: 64 Sheep: 54 Swine: 38 Turkeys: 82 - ANSWER-What is the chromosome number (diploid) for humans? Cattle? Chickens? Donkeys? Goats? Horses? Sheep? Swine? Turkeys? autosomes are not sex chromosomes - ANSWER-What is the difference between autosomes and the other chromosomes? -basic units of heredity -different forms of a particular gene -location; denotes the site of a particular gene - ANSWER-How do concepts of gene, allele, and locus differ? a mode of cell division in which reproductive cells are created that contain only one member of each pair of chromosomes - ANSWER-Explain, in general terms, what happens during meiosis? Linkage: when two loci occur on the same chromosome - ANSWER-Name one exception to Mendel's Law of Independent Assortment. 1. property of a pair of alleles at a locus 2. property of genes at different loci - ANSWER-How do dominance (1) and epistasis (2) differ? 1. male 2. female - ANSWER-In mammals, which parent dictates the sex of the offspring(1)? in birds(2)? they have to both carrier the recessive allele - ANSWER-If a genetic defect is a simple recessive, what has to be true about the parents for the offspring to show the defect? "gene and genotypic frequencies of a large, random mating population will remain constant from generation to generation, and the genotypic frequencies will equal the square of the gene frequencies, in the absence of migration, mutation, and selection." - ANSWER-Explain the Hardy-Weinberg Law. gene frequency after one generation of mutation equals zero. p= v/(u+v) - ANSWER-What do we mean when we say that a population is in equilibrium? What conditions are necessary for equilibrium? - ANSWER-How long does it take for a population not in equilibrium to reach that state if random mating occurs and gene frequencies are equal in both sexes? migration, mutation, selection, random drift - ANSWER-What are the four forces that change gene frequency? - ANSWER-What effect does each of the following have on gene frequency and variation: migration, mutation, selection, and genetic drift? Causes genetic abnormalities, spontaneous abortions - ANSWER-Is inbreeding a cause of mutations in livestock? - ANSWER-Describe a non-trivial example of migration in livestock and explain how it affected production. 1. difference in gene frequencies 2. proportion of migrants - ANSWER-What two things must be true for migration to have an important effect on a population? 1. imposed by humans 2. imposed by nature - ANSWER-Compare and contrast "artificial"(1) and "natural"(2) selection. - ANSWER-Compare changes in gene frequency when there is complete dominance and complete selection for a trait versus complete dominance and half-selection versus incomplete dominance and complete selection. Under which situation will rate of change be latest? Under which situation will total change be greatest? the current, or initial, gene frequency - ANSWER-What is the primary genetic effect of selection? 1. current gene frequency: only when alleles occur at intermediate frequencies are there enough "good" genes to select for and enough "bad" genes to select against that the cage in gene frequency can be fast 2. fitness: larger differences in fitness allow selection to be more effective 3. the degree of dominance expressed at that locus with respect to fitness - ANSWER-List three factors that affect response to selection. Describe their effects. a change in gene and genotypic frequencies due to chance - ANSWER-Explain the concept of genetic (or random) drift. more likely to change in small populations - ANSWER-What effect does herd (flock) size have on genetic drift?