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