Term
| Mendel’s Law of Segregation |
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Definition
| -allele pairs segregate equally into gametes during meiosis |
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Term
| You would like to know whether the progeny of a pair of mated fruit flies are distributed among the resulting four phenotypic classes in a 1:1:1:1 ratio. You perform a chi-square test and obtain a p value of 0.04. Assuming you have done the test correctly, select the best interpretation of this result. |
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Definition
-The differences between the observed and expected counts are too large to be attributed to chance.
-t is on this basis (p< 0.05) that the decision to reject the hypothesis of a 1:1:1:1 ratio is made. |
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Term
| The larger the number of total individual counts in a chi-square test, the higher the degrees of freedom (df). |
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Definition
| -df increases with increasing n (number of categories), but not necessarily with increasing number of subjects. |
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Term
| The expected ratio of phenotypes among the progeny of a test cross is 1:1:1:1. Out of 200 total resulting progeny, 48 occur in one of the four phenotypic classes. Given this information, which of the following must also be true? |
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Definition
=The value of observed - expected for this cell = -2.
-With a total of 200, the expected number in each cell when the predicted ratio is 1:1:1:1 = 50. The observed number is 48. |
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Term
The parent cell that enters meiosis is diploid, whereas the four daughter cells that result are haploid.
Which statement correctly describes how cellular DNA content and ploidy levels change during meiosis I and meiosis II |
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Definition
| -DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II. |
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Term
| Separation of sister chromatids occurs _______. |
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Definition
-at anaphase in mitosis
-anaphase II in meiosis |
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Term
| The end result of meiosis is four haploid daughter cells |
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Definition
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Term
| Novel combinations of genes can arise from _______. |
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Definition
| reciprocal exchange of DNA between homologs during prophase I |
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Term
| If a gene did not assort independently, but instead were linked to one another on the same chromosome. Would you expect the phenotypic ratio in the offspring to change? If so, how? |
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Definition
-All eight possible phenotypes could occur, but a greater proportion of the offspring would have the parental phenotypes.
-Because all three genes are linked, it is more likely that the parental allele combinations would stay together |
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Term
| Crossing over during prophase I of meiosis occurs between alleles on sister chromatids?? |
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Definition
| -Crossing over during meiosis occurs between alleles on nonsister chromatids. |
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Term
| Can parental gametes arise from cross-overs?? |
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Definition
| -If crossing over occurs, half of the gametes formed are parental and the other half are recombinant. |
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Term
| What may happen to 3-linked genes that are very close on a chromosome? |
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Definition
| -Interference effects are more likely when crossovers are confined to a small region. |
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Term
| What about location can determine how frequent recombinations occur? |
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Definition
-Further the distance= more cross-overs
-Shorter the distance=less cross-overs |
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Term
| What are unlinked genes? How frequently do they cross-over?? |
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Definition
-Unlinked genes assort randomly and are further apart
-Unlinked cross-over more frequently during meiosis |
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Term
| What are linked genes? How frequently do they cross-over?? |
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Definition
-Linked genes travel close together on the same chromosome and are much closer together than unlinked genes.
-The have a smaller chance of recombination than unlinked genes. |
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Term
| Genetic linkage leads to the production of a significantly greater than expected number of gametes containing chromosomes with?? |
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Definition
| -parental combinations of alleles. |
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Term
| Genes X, Y, and Z are linked. Crossover gametes between genes X and Y are observed with a frequency of 25%, and crossover gametes between genes Y and Z are observed with a frequency of 5%. What is the expected frequency of double crossover gametes among these genes? |
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Definition
| -The probability of a double crossover is the product of the probabilities of the single crossovers: 0.25 x 0.05 = 0.0125, or 1.25%. |
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Term
| What is the recombination frequency of 5 map units? |
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Definition
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Term
| Assume that the genes from the previous example are located along the chromosome in the order X, Y, and Z. What is the probability of recombination between genes X and Z? |
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Definition
-Recombination frequencies between linked genes along a chromosome are additive, so the recombination frequency between genes X and Z is 25 + 5 = 30.
-Remember map units and recombination are parallel to each other so these are fairly easy to determine |
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Term
| What lod score is associated with a significant likelihood of linkage? |
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Definition
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Term
| For a given cross, the expected number of double recombinants is 20 and the observed number of double recombinants is 15. What is the interference calculation (I)? |
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Definition
-Coefficient of Coincidence=Observed frequency/expected frequency of double recombination
-Interference= 1-C.o.C
-15/20=.75
-1-.75=.25 so 25% |
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Term
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Definition
-both alleles are equally stong and both alleles are visible in the hybrid genotype
-NOT BLENDED but a combination of both colors in different areas. |
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Term
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Definition
-a form of intermediate inheritance
-Forms a 3rd phenotype different from parentals
-The expressed trait is a COMBINATION of the dominant and recessive phenotypes. |
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Term
In 1905, Lucien Cuenot observed that crosses between two yellow mice consistently produced progeny ratios of two yellow : one agouti (wild-type). What is the explanation for the observed 2:1 phenotype ratio?
We know that the yellow allele is a recessive lethal, but what indicates this?? |
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Definition
| -This is a modified 1:2:1 ratio. Individuals that are homozygous for the yellow allele (AY/ AY) die during embryogenesis and therefore are not represented among the progeny |
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Term
| Which mode of inheritance results in the phenotype of a heterozygote being indistinguishable from that of an organism homozygous for the dominant allele? |
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Definition
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Term
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Definition
| dominant allele completely masks the effect of the recessive allele |
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Term
| Most people with the dominant mutant polydactyly allele have extra digits, but at least 25% have the normal number of digits. What is the genetic explanation for this observation? |
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Definition
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Term
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Definition
| not all individuals carrying a abnormal gene express it. |
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Term
| Independent assortment predicts a 9:3:3:1 ratio with four different phenotypes in the F2 progeny. If the alleles are epistatic, what would you predict? |
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Definition
| fewer than four phenotypes |
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Term
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Definition
| he effect of one gene being dependent on the presence of one or more 'modifier genes' |
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Term
| Two pure-breeding mutant plants produce white flowers. When they are crossed, all of the progeny have wild-type purple flowers. What does this genetic complementation tell you? |
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Definition
-More than one gene is involved in determining the phenotype
-mutations on different genes complement each other and will result in wild-type progeny |
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Term
| If mutations on the same gene what is the result? |
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Definition
-Failure to complement
-mutant progeny |
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Term
| If mutations are on different genes, what is the result? |
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Definition
-Successful complement
-Wild-type progeny |
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Term
| Ovules from a pure-breeding yellow plant are fertilized with pollen from a pure-breeding green plant. All of the progeny are yellow. When the reciprocal cross is performed, all of the progeny are green. What do these results suggest? |
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Definition
| -Color is maternally inherited. |
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Term
| Random segregation of organelles during cell division is likely to result in an increased rate of which of the following? |
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Definition
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Term
| You discover a mutation that causes mice to develop cramps in their legs. A female mouse of a true-breeding strain that develops cramps is mated with a male of a true-breeding non-cramp strain. All progeny develop cramps in their legs. Which of these procedures would you use to provide evidence for your hypothesis that twitchiness is due to mtDNA? |
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Definition
-Do a reciprocal cross
-breed crampy male progeny with normal females to show no paternal inheritance |
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Term
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Definition
| Traits from both mom and dad |
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Term
| Law of independent assortment |
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Definition
| The segregation of 1 gene pair is independent of the segregation of another gene pair. |
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Term
| What happens during Leptotene? |
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Definition
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Term
| What happens during Zygotene? |
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Definition
| Homologous chromosome pair up to form homologous chromosomes. |
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Term
| What happens during Pachytene? |
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Definition
| Beginning of chromosomal cross-over |
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Term
| What happens during Diplotene? |
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Definition
| The break down of the synaptonemal complex |
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Term
| What happens during Diakinesis |
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Definition
| Chiasmata is visible and nuclear envelope breaks down |
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Term
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Definition
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Term
| What happens during Metaphase I? |
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Definition
| Tetrads align along metaphase plate |
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Term
| What happens during Anaphase I? |
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Definition
| Homologous chromosomes separate, but sister chromatids remain attached |
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Term
| During Meiosis I, Anaphase I. What keeps sister chromatids together? |
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Definition
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Term
| What happens during Telophase I and Cytokinesis? |
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Definition
| Nuclear envelope re-forms and cell begins to divide |
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Term
| What happens during Meiosis II, generally? |
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Definition
| Sister chromatids separate |
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Term
| What happens during Prophase II? |
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Definition
-Nuclear envelope breaks down
-Microtubules come from centrosome |
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Term
| What happens during Metaphase II? |
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Definition
-Sister chromatids line up at metaphase plate
-Microtubules attach but there is resistance from cohesion |
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Term
| What happens during Anaphase II? |
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Definition
-Microtubles are connected to the kinetochore
-Cohesion breaks down as sister chromatids are separated |
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Term
| What happens during Telophase II and Cytokinesis II? |
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Definition
| -Re-formation of nuclear envelope and separateion of the cells. End up with 4 haploid cells. |
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Term
| What are the 3 types of molecular markers? |
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Definition
-Restriction Fragment Length Polymorphisms (RFLP)
-Simple Sequence Length Polumorphisms (SSLPs)
-Single Nucleotide Polymorphisms (snips) |
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Term
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Definition
| a single gene influences more than one phenotypic trait in an organism. |
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Term
| What is an organelle gene? |
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Definition
| -Only ONE parent is able to pass on the genome of a certain organelle. Most commonly the mitochondria in humans, and chlorplast in plants. |
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