Plant & Animal Genetics – Flashcards
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Unlock answers| Additive genetic component (?A) |
| A component of genotype. A measure of the sum of effects of allels working together. The only component that is inherited. |
| Allele |
| Different versions of a loci. A dominant allele is represented by a capital letter and the recessive by a lower case letter. |
| Anonymous marker panel approach |
| An approach to QTL detection. A panel of markers is developed. Then multiple markers are used to scan a region, chromosome, or genome. Uses high density marker panels. |
| ANOVA |
ANalysis Of the phenotypic VAriance A regression based method of testing for significance. If Pr>F is less than 0.05, there is significance. |
| Artifical selection |
| Selection controlled by humans. Goal oriented towards an animals' appearance, use, productivity, or even just whimsy. |
| Avian sex determination |
Male birds have two Z chromosomes: ZZ Female birds have one Z chromosome: Z_ (sometimes written as Zw |
| Biddability |
| A CARAT trait for guide dogs. How well a dog does the bidding of a human. |
| Binary trait |
| A threshold trait with two classes. A yes/no situation. Example: diabetes. |
| Bottleneck |
| Moderate pressure natural selection. Cheetahs had a large bottleneck 10 - 15 thousand years ago. Cheetahs are all closely related. |
| Calving ease |
| A quantitative trait. Categorized into unassisted, easy pull, hard pull, and surgical. |
| Candidate gene approach |
| An approach to QTL detection. A gene is selected for physiological or biochemical reasons, and the polymorphism is detected within the gene. One at a time, selective, and targeted searching. Carefuly organized and tedious. |
| CARAT traits |
| Traits that are looked for in service dogs. Determined using a series of 36 tests. Dogs are scored by their performance. |
| Confidence with other dogs |
A CARAT trait for service dogs. h2 = 0.26 |
| Confidence with people |
A CARAT trait for service dogs h2 = 0.17 |
| Conformation final score |
A phenotype looked for in cattle. Includes rump, feet, and legs. h2 = 0.21 |
| Counting method |
| A method of calculating allele frequency. The genotypes of individuals are counted up, and the alleles counted. Population must be small enough to ount and the genotype of all individuals must be known. |
| Cross country |
A racing event for horses with fixed obstacles. Success in this competition is a hertiable trait. h2 = 0.41 |
| Cross-dressing roosters |
| An example of sex-limited inheritance. All hens show characteristic hen feathering. Cocks with a dominant H allele (HH or Hh) show hen feathering. Homozygous recessive cocks (hh) show characteristic cock feathering. |
| Cull |
| The genetic equivalent of death in artificial selection. It may be slaughter, neutering, or preventing that animal from breeding. |
| Cut-off point (t) |
aka Truncation point In quantitative trait selection, the point in the phenotypic sliding range where individuals survive or are culled. |
| Detection of carriers |
Calculating the probability that a dominant phenotype individual is heterozygous without a test cross, where the individual mates randomly. P = [f(AA) + 0.75f(Aa) + 0.5f(aa)]n |
| Dominance genetic component (?D) |
| A component of genotype. A measure of combined dominance effects of individual loci. |
| Draft horse |
| The genetic differences between large horses and small horses is one section of the genome. |
| Drip loss |
| The loss of water from meat while in storage. If it is really bad, the meat can become concave. It is a heritable trait in pigs. |
| Easy pull |
| A class of calving ease. Cow needs a small amount of assistance in birth. |
| Environment (?E) |
| A component of phenotype. The conditions in which the genotype is expressed. Changes to this factor (altering diet, habitat, et cetera) are reversible. |
| Epistasis |
| When alleles at one locus effect the expression of alleles at a different locus. Example: a white cat has a genotype of W_, and a genotype of ww allows other colour patterns to express. |
| Evolution |
| Subtle pressure of natural selection. |
| Extinction |
| Massive pressure natural selection. |
| Fat percentage |
A phenotype in cows. h2 = 0.5 |
| Fat yield |
A phenotype in cows. h2 = 0.34 |
| Feet and legs conformation |
A phenotype in cattle h2 = 0.12 |
| Fertility |
A phenotype in cattle h2 = 0.07 |
| Fitness (w) |
| The suitability of an animal's phenotype to its environment, be that a natural or artificial environment. Expressed as a fraction representing how many of the individuals with that phenotype will reproduce. |
| Gaited horse |
| A horse with a particular way of running where the horse's back does not move up and down as much. There is genetic basis for this phenotype. |
| Genotype (?G) |
A component of phenotype. Many loci contribute to it. Changes to this factor (breeding), are permanent. ?G = ?A + ?D + ?I |
| Genotyping |
| Determining the genotypes of individuals. The challenge is to decrease the cost per genome, and increase the number of loci. Can be expensive. |
| Gold/silver chicken sexing |
| A method of maxing determining the sex of chicks easier. A silver hen (S_) is crossed with a gold cock (gg). All the female chicks will be gold (g_) and all the male chicks will be silver (Sg). |
| Hard pull |
| A class of calving ease. Cow needs a large amount of assistance in birth. |
| Hardy-Weinberg equilibrium |
Population must be large with random mating, and lack migration, mutation, and selection. All allele and genotypic frequencies remain constant 1 = p2 + 2pq + q2 |
| Herd life |
A phenotype in cattle h2 = 0.1 |
| Heritability (h2) |
The portion of total variance that is additive genetic. Half is transmitted to offspring h2 = ?A2 / ?P2 |
| High density marker panel |
| A device used in anonymous marker panel approach of QTL detection. Photo etches 50,000 - 1,000,000 markers onto a glass slide, building "velcro" tags that "grab" matching DNA. The grabbed areas light up, thus genotyping the individual. A thousand times cheaper, and faster than PCR method. |
| Highland cattle |
| A cattle breed bred to survive harsh environments. Smaller size, thicker coat. Can survive rough conditions on marginal feed. |
| Holstein |
| A cattle breed bred for high milk production. Require high quality feed to produce milk at the rate they do. Prevalent in the dairy industry. |
| Horned/polled sheep |
| An example of sex-limited inheritance. Homozygous deominant (PP) sheep are horned. Homozygous recessive (rr) sheep are polled. Heterozygous ewes (Pp) are polled, and heterozygous rams (Pp) are horned. |
| i |
i = S / ?P Depends on the proportion of the population selected in quantitative trait selection. Use the standard distribution curve table to find values based on the S value (portion of the population that is selected). |
| Inheritance |
| A factor affecting QTL detection. Crosses of divergent lines (looking for multi-modal distribution), offspring-parent resemblance (deviation from the parent average), and segregation analysis (expected inheritance using pedigree). |
| Imprinting |
| Genes expressed only if they are inherited from a particular parent (from the mother or father). One of the parent's genes is destined to be inactive because of their sex. |
| Interaction genetic component (?I) |
aka Epistasis A componenet of genotype. A measure of the combined interactions between loci. |
| Johanna Rag Apple Pabst |
| A bull who is the ancestor of 99.5% of all Canadian Holsteins. Came from Quebec, but lived in Guelph. |
| Large population |
| One of the requirements for Hardy-Weinberg equilibrium. Populations must be large enough to maintain Hardy-Weinberg equilibrium. Generally too arge to count all individuals. |
| Lethal allele |
| An allele with an s value of 1. May actually be lethal to the animal, causing abortion or early death, or just that humans cull every single individual carrying the allele. |
| Linkage |
| When two or more loci are on the same chromosome. |
| Mammalian sex determination |
Female mammals: XX Male mammals: XY |
| Marker |
| Unimportant polymorphisms that occur nearby to QTL, so recombine with the QTL. They often have no genotypic effect on the phenotype. Used to locate QTLs. If the marker and QTL are separated by recombination, then it is useless. |
| Mass selection |
| Used when there are many progeny, such as in fish or poultry. |
| Mean (X bar) |
aka Average X bar = (? xi) / n |
| Meishan pig |
| A pig that produces very large litters up to 30 piglets! The large litter size is due to a single SNP in the NCOA1 gene. |
| Melanocytes |
| Cells that produce fur pigments in cats. They also affect the electrical transmission of electrical signals from the ear to the brain. As a result, white cats are often also deaf. White cats are only deaf if they have blue eyes. If just one eye is blue, the cat is deaf on that side. |
| Mendelian Genetics |
aka Classic genetics Crossing two heterozygoes (Aa x Aa) gives 1AA : 2Aa : 1aa |
| Migration |
One of the limits of the Hardy-Weinberg equilibrium. The alleles move from one population to another. May be due to climate change, human activities, or humans shipping germplasm. Depends on the immigration rate and the difference in allele frequencies betwen the populations. P' = allele frequency in migrant population M = percentage of population that are migrants P' = p1 + m(p2 - p1) |
| Milk yield |
A phenotype in cows h2 = 0.43 |
| Mutation |
| A limit on Hardy-Weinberg equilibrium. New alleles are created. Most mutations are recessive. If the mutation phenotype has fitness at or above that of the wild type, the mutation will not go away. |
| Natural selection |
| Selection by the environment. Individuals must adapt to the environment or perish. Includes evolution, bottlenecks, and extinction. |
| P |
| The selected portion of the parent population in quantitative trait selection. |
| PCR |
aka "genetic horserace" Endonuclease cleaves DNA at specific sequenes and then is put in a gel to determine genotype. Slower and more expensive than high density marker panels. |
| Persistence with other dogs |
A CARAT trait. h2 = 0.16 |
| Phenotypic variance (?P2) |
| ?P2 = (?A2 + ?D2 + ?I2) + ?E2 |
| Phenotype (?P) |
| Determined by a combination of genetics and environment. |
| Phenotypic selection |
| Selection for quantitative traits. Selection based on phenotype. Indirectly influencing allele frequency. Tracking progress by change in phenotype. |
| Pleiotropy |
| When one locus affects two or more traits. Example: white cats are often also deaf. |
| Polymorphism |
| A differene in alleles. Example: SNPs. |
| Population design |
| A factor affectin QTL detection. Inbred line crossing, and outbred populations. |
| Proportion method |
A method of calculating allele frequency. The genotypes of individuals are counted. f(AA) = P f(Aa) = H f(aa) = Q f(A) = P + 0.5H f(a) = Q + 0.5H |
| Protein percentage |
A phenotype in cows h2 = 0.5 |
| Protein yield |
A phenotype in cows. h2 = 0.4 |
| Qualitative trait |
| Controlled by one or few loci. Discrete phenotypes. Traits are selected with single locus selection. Easy to predict if the allele frequency is known. Genotype can be determined in a lab. |
| Quantitative trait |
aka Polygenic trait Controlled by multiple loci, up to thousands. Most of the loci have small effects on the phenotype, so are difficult to pinpoint. Some of the loci may have a larger effect on phenotype, so may be located. Phenotypes occur on a continuous sliding scale. Include threshold traits. Traits are selected wth phenotypic selection. |
| Quantitative triat locus (QTL) detection |
| Finding polymorphisms in a genome that is associated with a distinctive difference in phenotype. Can be complicated. Often QTL are discovered using markers. Two methods: candidate genes, and anonymous markers. Affected by inheritance and population design. |
| Race earnings |
A phenotype in horses h2 = 0.25 |
| Racing speed |
A phenotype in horses h2 = 0.25 |
| Random mating |
| One of the requirements for Hardy-Weinberg equilibrium. All allele frequencies remain constant. This generally excludes human populations because random mating is not socially acceptable in human societies. |
| Red & White spotting |
| An example of sex-influenced inheritance in Shorthorn cattle. Homozygous dominant (RR) cattle have red and white spotting. Homozygous recessive (rr) cattle are white. Heterozygous (Rr) cows are red and white spotted, and heterozygous (Rr) bulls are white. |
| Response (R) |
In quantitative trait selection, the deviation of the progeny from the original population average R = [average of offspring] - [average of parent population (including unselected)] |
| Rump conformation |
A phenotype in cattle h2 = 0.23 |
| SAS analysis |
| A computer program that determines how well a model fits with the observed phenotypes. The smaller the Pr>F value, the more likely the model is valid. |
| Secretariat |
| A racehorse who won races by a large margin. Lived in 1973. Turned out he was not above average in speed, but just looked fast compared to the other horses. |
| Selection |
A limit of Hardy-Weinberg equilibrium. The process which determines which individuals will become parents of the next generation. Includes natural and artificial selection. Allele frequencies are altered. p1 = (p0(1 - s1q0) / (1 - 2s1p0q0 - s2p02) |
| Selection differential (S) |
In quantitative trait selection, the average of selected parents deviated from the population mean. S = [average of selected parents] - [average of parent population] |
| Selection pressure (s) |
| How many individuals in a phenotype survive and become parents. |
| Sex-influenced inheritance |
| Heterozygoes express a different phenotype in males than in females. |
| Sex-limited inheritance |
| Phenotypes can be observed only in one sex. Sexes may not even possess the necessary body parts for certain phenotypes. |
| Sex linkage |
| When a gene is found on a sex chromosome. |
| Show jumping |
A phenotype in horses h2 = 0.45 |
| Significance |
| When Pr>F is less than 0.05. The hypothesis will be incorrect 5% of the time. |
| Single locus selection |
| Selection of qualitative traits. Selecting based on alleles. Directly influencing allele frequency. Track progress with allele frequency. |
| Single nucleotide polymorphism (SNP) |
| Pronounced "snip". A single change of base in DNA. |
| Social interactions with people |
A CARAT trait for service dogs. h2 = 0.47 |
| Standard deviation |
| The square root of variance. |
| Surgical |
aka Mal-presentation. A class of calving ease. Cow needs surgery in birth. Calf pushed back, turned around, and then pushed out the right way. |
| Test cross |
| Crossing a dominant phenotype indiviual with a recessive phenotype individual. If any of the offspring have the recessive phenotyp, the individual is heterozygous. |
| Threshold trait |
| Quantitative traits that are categorized into discrete groups on the sliding scale. Includes calving ease and binary traits. |
| Ultimate selection pressure |
| In qualitative trait selection, when one allele has a fitness level of zero in both homozygous and heterozygous forms. By the second generation, the allele frequency is zero. |
| Unassisted |
| A class of calving ease. The cow gives birth without any human help. |
| Variance (?2) |
The measure of diversity and variety in a phenotype. The square root of variance is standard deviation. ?2 = (? (x - x bar)2) / (n - 1) |
| Visual reactivity |
A CARAT trait in service dogs. h2 = 0.18 |
| Whining |
An unwanted CARAT trait in service dogs. h2 = 0.06 |
| Z |
| The height of the standard distribution curve at the cut-off point. |
