| Question | Answer |
| polygenes/quantitative trait loci (QTLs) | Several to many alleles interact with more or less additive effect. Greater number of polygenes, more smoothly the bell graph of their frequencies. Variation and assortment of polygenes can contribute to continuous variation in a population |
| polygenic inheritance | Characters that can take any measurable value between two extremes Eg: Height, weight, color intensity AKA “metric” or “quantitative characters” Many cases have purely an environmental basis |
| what does a recombinant frequency of 50% indicate | that the genes are independently assorting and are most likely on different chromosomes. |
| recombination frequency of genes on different chromosomes | produced by independent assortment. Genes that are very far apart on the same chromosome pair can assort virtually independently and produce the same result. 50% recombinant frequency for independent assortment. |
| 2 cellular processes that create recombinants | independent assortment and crossing over |
| recombinant frequency | Numerical value. Proportions of recombinants can tell us whether genes are on different chromosomes or the same chromosome. |
| how do you detect recombinant output gametes | test-cross the diploid individual and observe its progeny |
| recombinant | Any meiotic product that has a new combination of the alleles provided by the two input genotypes |
| meiotic recombination | Any meiotic process that generates a haploid product with new combinations of the alleles carried by the haploid genotypes that united to form the meiocyte. Detect recombination by comparing inputs into meiosis with the outputs |
| recombination | Production of a new allele combination. Provides variation as the raw material for natural selection. Independent assortment and crossing over two ways this happens |
| hybrid vigor | The general superiority of multiple heterozygotes. the hybrid shows greater size and vigor that the two contributing lines individually. Molecular reasons still unknown, and highly debated. To make a hybrid line, two parental lines must be grown separately then intercrossed. Much more inconvenient because you have to make 2 pure lines. Some hybrids between genetically different lines show hybrid vigor. However, gene assortment when the hybrid undergoes meiosis breaks up the favorable allelic combination, and thus few members of the next generation have it. |
| how do you synthesize pure lines | Pure lines are fully homozygous lines that will express recessive alleles. Maintenance stocks of pure lines kept for research as a constant source of the genotype in experiments. Pure lines made through repeated generations of selfing. Every time an organism is selfed, the heterozygosity has halved. Repeated selfing leads to an increased proportion of homozygotes, a process that can be used to create pure lines for research or other applications. |
| what does the probability value of a chi-square test actually mean? | Probability of observing a deviation from the expected results at least as large on the basis of chance if the hypothesis is correct |
| degrees of freedom | Number of degrees of freedom is the number of independent variables in the data. |
| chi square equation | ∑(O - E)^2 / E for all classes. In which E is the expected number in a class, O is the observed number in a class, and ∑ means “sum of.” Calculation performed by using a table |
| chi-square test | Results that are close to an expected ratio but not identical with it. Statistical test that checks ratios against expectations. Observed results compared with predicted. Tells whether they are close enough to predicted results. Quantifies various deviations by chance if a hypothesis is true. |
| How many distinct genotypes will a cross produce? | Number of genotypes or phenotypes in the progeny of complex parental strains |
| how many progeny do we need to grow? | First, calculate the proportion of progeny that is expected to be of that genotype Need to get 95% confidence Calculate the probability of not getting desired genotype. (1 - 1/256, eg) With sample size, n, the probability of no success in a sample of n is raised to the n power (255/256)^n So the probability of at least one success is 1 - probability of no success ^ n (1 - (225/256)^n) Make this probability equal to .95 and solve for n to find the critical sample size 1 - (255/256)^n = .95 |
| What proportion of progeny will be of a specific genotype? | Assume gene pairs assort independently. Use product rule |
| sum rule | The sum rule states that the probability of either of the two mutually exclusive events occurring is the sum of their individual probabilities. Focus on the outcomes of A’ or A”. |
| product rule | The project rule states that the probability of independent events both occurring together is the product of their individual probabilities. Focus on the outcomes A and B. |
| three methods for predicting progeny ratios from parent's known genotypes | punnett squares, branch diagrams, product rule and sum rule |
| Ratio diagnostic of independent assortment in two dihybrid meiocytes | 9:3:3:1 |
| Ratios diagnostic of independent assortment in one dihybrid meiocyte | 1:1:1:1 |
| mendel's second law | Different gene pairs assort independently in gamete formation Mendel’s second law only applies to genes on different chromosomes |
| ratio of dihybrid cross with independent assortment | yields a phenotype ratio of 9:3:3:1 (really a 3:1 ratio for each gene) |
| dihybrid cross | Cross two dihybrids |
| dihybrid | Double heterozygote such as A/a•B/b |
| two genes on unknown chromosomes | gene pairs separated by dot |
| two genes on same chromosome | gene pairs not separated by punctuation |
| two genes on different chromosomes | gene pairs separated by semicolon |
| independent assortment | When two genes are on different chromosome pairs. The different chromosomes act independently at meiosis and the alleles of the two heterozygous gene pairs arrange independently. This does not happen when the two genes are on the same chromosome. |
32 cards - created oct 18, 12:56am