Animal Science Chapters 12-14

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What are the functional units of inheritance?: genes
From which process are more body cells produced?: mitosis
Which livestock animals have the most pairs of chromosomes?: poultry
Which livestock animals have the least pairs of chromosomes?: swine
In which process are sex cells produced?: gametogenesis
What are the male and female gametes?: male-sperm
female-eggs
What is the cell division in which gametes are formed?: meiosis
Where does meiosis occur?: in the primordial germ cells
What occurs to a cell before it is called a primary spermatocyte or oocyte?: chromosome replication and synapsis
How many sperm are produced from each primary spermatocyte?: 4
How many chromosomes are present in the primordial germ cell?: 4 (2 pairs)
How many chromosomes are present in each sperm?: 2 (1 pair)
What does the first maturation division of oogenesis produce?: a secondary oocyte and the first polar body
What does the second maturation division of oogenesis?: an egg and the second polar body
How many chromosomes are present in each egg?: 2 (1 pair)
What is the fertilized egg called?: a zygote
Is the zygote haploid or diploid?: diploid
Are gametes haploid or diploid?: haploid
What process in gametogenesis re-establishes the diploid number?: fertilization
What are homologous chromosomes?: chromosomes that have the same size and shape and carry genes that affect the same hereditary characteristics
What is the purpose of genes?: to direct enzyme and protein production
What is the structural configuration of DNA?: a double helix
What is the locus?: the location of a gene on a chromosome
Which three products make up DNA?: deoxyribose sugar, phospate, and four nitrogenous bases
What is the nucleotide made up of?: deoxyribose, phosphate, and a nitrogenous base
What are the four nitrogenous bases of DNA?: adenine, thymine, guanine, and cytosine
How are nitrogenous bases coupled in DNA?: A-T
C-G
What are the three types of RNA?: transfer, messenger, and ribosomal
What is the first step in protein synthesis?: transcription
What is a codon?: the triplet sequence that codes for one amino acid in mRNA
Where does protein synthesis take place?: in the ribosome
What is the second step of protein synthesis?: the union of amino acids with their respective tRNA molecules
What binds with the mRNA codon?: the anticodon in the tRNA
Which chromosomes determine the sex of offspring?: the X and Y chromosomes
What are homozygous chromosomes?: chromosomes in which the genes located at corresponding loci correspond with each other in the way they control a trait
What are heterozygous chromosomes?: chromosomes in which the genes located at corresponding loci contrast with each other in the way they control a trait
What are alleles?: genes that occupy corresponding loci in homologous chromosomes but that affect the same trait in a different way
What are identical alleles?: genes that are alike and affect the character in the same way
What are the 6 mating possibilities with homozygous-dominant, heterozygous, and homozygous-recessive parents?: 1) BBxBB
2) BBxBb
3) BBxbb
4) BbxBb
5) Bbxbb
6) bbbxbb
What is the ratio of offspring produced by the BbPpxBbPp combination?: 9 black polled
3 black horned
3 red polled
1 red horned
What is linear interaction?: the interaction of a gene with other genes in the same chromosome
What is allelic interaction?: the interaction of a gene with its corresponding gene in a homologous chromosome
What is epistatic interaction?: the interaction of a gene with genes in nonhomologous chromosomes
What is an internal environmental factor that interacts with genes?: hormones
What are three external environmental factors that interact with genes?: nutrition, temperature, and amount of light
What occurs in complete dominance?: unlike genes occupy corresponding loci and only the effect of the dominant gene is expressed
When does lack of dominance occur?: when a phenotype is shown that is intermediate between the two homozygous phenotypes
What do the more vigorous crossbred offspring possess?: heterosis
What is partial dominance?: when the heterozygote expresses a phenotype that is intermediate to either homozygote but more closely resembles the homozygous dominant pairing
What is an example of partial dominance?: the presence of hyperkalemic paralysis in horses
What is the most important external environmental factor on genes?: feed supply
What is biotechnology?: the use of living organisms to improve, modify, or produce industrially important products or processes
What are quantitative traits?: those that can be objectively measured and are controlled by many gene pairs
What are qualitative traits?: those that are visible to the eye and are controlled by few gene pairs
What is the phenotype?: the observation or measurement of each trait
What two sources cause phenotypic variation?: genotype and environment
What is breeding value?: the portion of the genotype that can be transferred from parent to offspring
-OR-
the total of all the independent genetic effects in an animal on a given trait
What is nonadditive value?: the portion of genotype that is attributed to the gene combinations unique to a particular animal
What are known environmental effects?: those that have an average effect on indivuals in a specific category
What are unknown environmental effects?: those that are random and are specific to an individual phenotype
Can unknown or known effects be quantified?: known
What is selection?: preventing some animals from reproducing while allowing other animals to breed commonly
What are the three factors that affect the rate of genetic improvementfrom selection?: selection differential, heretability, and generation interval
What is selection differential also called?: reach
What is selection differential?: the superiority of selected animals compared to the herd average
What is heritability?: the percent of total phenotypic that is due to breeding value
-OR-
the portion of the selection differential that is passed from parent to offspring
What is realized heritability?: the portion of heritability actually obtained compared to what was attempted in selection
Which traits are considered highly heritabile?: those that have heritability estimates of 40% and higher
Which traits are considered mediumly heritable?: those that have heritability estimates between 20 and 39%
Which traits are considered to have low heritability?: those that have heritability estimates lower than 20%
average age of the parents when the offspring are born: generation interval
species in which artificial insemination is used more than any other species: dairy cattle
three methods of selection for genetic change: tandem, independent culling level, and selection index
What is the tandem method?: selection for one trait at a time
What is the independent culling level selection method?: establishing minimum culling levels for each trait
the most prevalent selection method: independent culling level
What is the selection index selection method?: establishing a culling level for multiple traits
the most effective selection method: selection index
the basis for modern selection: expected progeny differences
are most commercial slaughter livestock purebred or crossbred?: crossbred
the mating of closely related animals whose ancestors have been inbred for several generations: intensive inbreeding
mild inbreeding where a high genetic relationship is maintained with an ancestor or line of ancestors: linebreeding
four types of outbreeding: species cross, crossbreeding, outcrossing, grading up
crossing of animals of different species: species cross
mating of animals of different breeds: crossbreeding
mating of unrelated animals within the same breed: outcrossing
mating of purebred sires to commercial-grade females and their offspring for several generations: grading up
is heterosis highest for low-heritability or high-heritability traits?: low-heritability traits
the most widely used breeding system: outcrossing

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