ch 15 mb biol 14016

Which of the following are the phenotypes of the parents in this cross?

4 and 8

A sex-linked gene for eye color in Drosophila The inheritance of eye color in Drosophila is controlled by genes on each of the fly's four chromosome pairs. One eye-color gene is on the fly's X chromosome, so the trait is inherited in a sex-linked manner. For this sex-linked trait, the wild-type (brick red) allele is dominant over the mutant vermilion (bright red) allele. A homozygous wild-type female fly is mated with a vermilion male fly. X+X+×XvY Predict the eye colors of F1 and F2 generations. (Assume that the F1 flies are allowed to interbreed to produce the F2 generation.)

F1 Females: all wild type F2 Females: all wild type F1 Males: all wild types F2 Females: 1/2 wild type, 1/2 vermilion

Imagine a human disorder that is inherited as a dominant, X-linked trait. How would the frequency of this disorder vary between males and females?

Females would display this disorder with greater frequency than males.

The χ2 value means nothing on its own--it is used to find the probability that, assuming the hypothesis is true, the observed data set could have resulted from random fluctuations. A low probability suggests the observed data is not consistent with the hypothesis, and thus the hypothesis should be rejected. What is the hypothesis that you are testing?

The two genes are unlinked and are assorting independently, leading to a 1:1:1:1 ratio of phenotypes in the offspring.

Between which values on the df = 3 line does your calculated χ^2 value lie?

between 1.42 and 2.37

What is the chance that any daughter that the couple will be color blind with a widow's peak?

0

What is the probability range that your data fit the expected 1: 1:1:1 ratio of phenotypes?

0.50 < p < 0.70

Suppose the couple had a daughter with normal color vision and a widow's peak. What is the chance that she is a heterozygous for both genes?

1

How are human mitochondria inherited?

from the mother only

The diagram below shows two normal chromosomes in a cell. Letters represent major segments of the chromosomes. The diagram shows two chromosomes. The first chromosome, green, consists of two arms. The left arm, short, consists of segments A and B. The right arm, long, consists of a sequence of C, D, E, F, G, and H segments. The second chromosome (yellow) consists of two arms. The left arm, short, consists of a segment I. The right arm, long, consists of a sequence of J, K, L, M, and N segments. The following table illustrates some structural mutations that involve one or both of these chromosomes. Identify the type of mutation that has led to each result shown. Drag one label into the space to the right of each chromosome or pair of chromosomes. You can use a label once, more than once, or not at all.

1. deletion 2. duplication 3. translocation 4. inversion 5. duplication 6. translocation 7. inversion

What is the chance that any son the couple has will be color blind with a straight hairline?

1/2

Down syndrome is caused by trisomy 21, the presence of three copies of chromosome 21. The extra copy usually results from nondisjunction during meiosis. In some cases, however, the extra copy results from a translocation of most of chromosome 21 onto chromosome 14. A person who has had such a translocation in his or her gamete-producing cells is a carrier of familial Down syndrome. The carrier is normal because he or she still has two copies of all the essential genes on chromosome 21, despite the translocation. However, the same may not be true for the carrier's offspring. The diagram shows the six possible gametes that a carrier of familial Down syndrome could produce. Suppose that a carrier of familial Down syndrome mated with a person with a normal karyotype. Which gamete from the carrier parent could fuse with a gamete from the normal parent to produce a trisomy-21 zygote? Drag one of the white cells (representing gametes) to the white target in the diagram. Drag one of the pink cells (representing zygotes) to the pink target.

14 (green) 21 (yellow) 21 (yellow) 14 (green) 21 (yellow) 14 (green) 14 (green) 21 (yellow) 21 (yellow) 21 (yellow)

In cosmos plants, purple stem (A) is dominant to green stem (a), and short petals (B) is dominant to long petals (b). In a simulated cross, AABB plants were crossed with aabb plants to generate F1 dihybrids (AaBb), which were then test crossed (AaBb X aabb). 900 offspring plants were scored for stem color and flower petal length. The hypothesis that the two genes are unlinked predicts the offspring phenotypic ratio will be 1: 1:1:1. Using the ratio of 1:1:1:1, calculate the expected number of each phenotype out of the 900 total offspring. Drag the correct values onto the data table. Labels may be used once, more than once, or not at all.

225, 225, 225, 225

What does a frequency of recombination of 50% indicate? .

The two genes are likely to be located on different chromosomes

In which progeny phenotypes has there been recombination between genes A and B?

1, 2, 5, and 6

Suppose a diploid cell with three pairs of homologous chromosomes (2n = 6) enters meiosis. How many chromosomes will the resulting gametes have in each of the following cases?Drag one label into each space at the right of the table. Labels can be used once, more than once, or not at all.

1. 3 only 2. 2 or 4 3. 0 or 6 4. 2, 3, or 4 5. 0, 3, or 6

The inheritance of both a sex-linked trait and an autosomal trait in humans Red-green color blindness is due to an X-linked recessive allele in humans. A widow's peak (a hairline that comes to a peak in the middle of the forehead) is due to an autosomal dominant allele .Consider the following family history: A man with a widow's peak and normal color vision marries a color-blind woman with a straight hairline. The man's father had a straight hairline, as did both of the woman's parents Use the family history to make predictions about the couple's children. If the couple has a child, what is the chance that it will be a son with a widow's peak?

1/4

The goodness of fit is measured by χ2. This statistic measures the amounts by which the observed values differ from their respective predictions to indicate how closely the two sets of values match. The formula for calculating this value is: χ^2=∑(o−e)^2/e where o = observed and e = expected. The expected and observed data have been entered into the table below. Carry out the operations indicated in the top row. In the last column, enter your answers to two decimal places. Then add up the entries in the last column to find the χ^2 value.

Deviation (o-e): -5 -15 6 14 (o-e)^2 25 225 36 196 (o-e)^2/e .11 1 .16 .87 Sum 2.14

Which of these descriptions of the behavior of chromosomes during meiosis explains Mendel's law of independent assortment?

The arrangement of each pair of homologous chromosomes on the metaphase plate during metaphase I is random with respect to the arrangements of other pairs.

Which of the following statements regarding gene linkage is correct?

The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.

Based on whether there are non-significant differences (p > 0.05) or significant differences (p ≤ 0.05) between the observed and expected values, you can determine if the data are consistent with the hypothesis that the two genes are unlinked and assorting independently. Do your results support the hypothesis that the stem color and petal length genes are unlinked and assorting independently, or do the observed values differ from the expected values enough to reject this hypothesis?

The hypothesis is supported. Because 0.50 < p < 0.70, the differences between the observed and expected values are not stat

Which of these descriptions of the behavior of chromosomes during meiosis explains Mendel's law of segregation?

The two alleles for each gene separate as homologous chromosomes move apart during anaphase I.

How would one explain a testcross involving F1 dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced?

The two genes are closely linked on the same chromosome.

The inheritance of a skin condition in humans Consider the following family history: Bob has a genetic condition that affects his skin. Bob's wife, Eleanor, has normal skin. No one in Eleanor's family has ever had the skin condition. Bob and Eleanor have a large family. Of their eleven children, all six of their sons have normal skin, but all five of their daughters have the same skin condition as Bob. Based on Bob and Eleanor's family history, what inheritance pattern does the skin condition most likely follow?

X-linked dominant

In general, the frequency with which crossing over occurs between two linked genes depends on __________.

how far apart they are on the chromosome