Concept explainers
The Rainbow Connection
The genetic variability or the Giddings children started out as mutations that occurred thousands of years ago. Take hair color: Our distant ancestors probably all had dark hair, its color controlled by multiple genes located on several different chromosomes. The alleles that produced Tess's blond hair originated as mutations in genes that control the amount and type of hair pigment. Tess probably inherited only “pale hair” alleles of all of these genes, so for any given hair color gene, she has the same pale hair allele on both homologous chromosomes. Chris, on the other hand, inherited both dark and pale hair alleles for at least some of the genes, so his homologues have different alleles. As we will see in Chapter 11, in many cases one allele (in this case, the dark hair allele) overrides the effects of the other allele (the pale hair allele), so Chris has black hair. What combinations of alleles might have been packaged in Tess's eggs and Chris's sperm, which would combine to produce their diverse children?
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Biology: Life on Earth with Physiology (11th Edition)
- Part Carrow_forwardTo understand this research, you must be familiar with some basic genetic terminology. Drag the terms on the left to the appropriate blanks on the right to complete the sentences. Not all terms will be used. dominant allele phenotype The possession of two different alleles of a particular gene is referred to as Reset Help A variation in a DNA sequence at one particular position is called a heterozygosity genotype recessive allele homozygosity single nucleotide polymorphism The appearance of the organism, its observable traits, are referred to as the A variant of a gene for which an individual must be homozygous in order for it to influence the appearance of the organism is a The set of alleles an organism has for a particular trait is the organism's Submit Request Answerarrow_forwardAlbinism is a recessive trait in humans.A geneticist studies a series of families in which both parents have normal pigmentation and at least one child has albinism. The geneticist reasons that both parents in these families must be heterozygotes and that albinism should appear in 14 of their children. To his surprise, the geneticist finds that the frequency of albinism among the children of these families is significantly greater than 14. Can you think of an explanation for the higher-than-expected frequency of albinism among these families?arrow_forward
- Albinism is a recessive trait in humans . A geneticist studies a series of families in which both parents havenormal pigmentation and at least one child has albinism. The geneticist reasons that both parents in these families must be heterozygotes and that albinism should appear in 14 of their children. To his surprise, the geneticist finds that the frequency of albinism among the children of these families is significantly greater than 14. Can you think of an explanation for the higher-than-expected frequency of albinism among these families?arrow_forwardwhat is the approximate map distance between the two genes? Show your work.arrow_forwardTay-Sachs disease is caused by loss of function mutation in a gene on chromosome 15 that codes for an enzyme. The disease is an inherited autosomal recessive condition which is found amongst Ashkenazi Jews of Central European origin. In this population, 2 in 4,900 children are born with the disease. What proportion of the population are carriers (heterozygotes) for this disease? ALL WORKING MUST BE SHOWNarrow_forward
- Drosophila can have 1, 2, or 3 stripes on their body. From previous experiments, you suspect that there are 2 genes (Gene C and Gene D) that control the number of stripes. A recent published paper described a similar stripe pattern in bees. Furthermore, in bees, Gene C is recessively epistatic to Gene D, are on different chromosomes, and the order of function is the following: C D 3 stripes → 2 stripes 1 stripe You therefore set out to test the hypothesis that Gene Cis also recessively epistatic to Gene D in Drosophila. To do so, you begin by crossing pure breeding 1-striped drosophila with pure breeding 3-stripped drosophila. To statically test your hypothesis, you proceed to perform a chi-square analysis on data obtained from the F1 X F1 cross. Using your hypothesis as your basis to analyze the results, fill the table below. Note: You do not have to calculate the chi-square or make a conclusion. Just fill the table. Observed Еxpected Нуpothesized Phenotypic ratio Phenotypes F2…arrow_forwardplease make sure to read the question (THERE ARE OTHER VARIATIONS OF THE QUESTION ON DIFFERNT WEBSITES THAT ARE DIFFERENT THAN MINE)arrow_forwardYou are a studying the genetic basis of horn color in unicorns. Gene C determines the color of pigment destined for the horn by converting a pink precursor into a purple pigment. C- individuals make purple pigment whereas cc individuals accumulate pink precursor. Gene D ensures the deposition of the pigment into the horn cells, such that D- individuals have a colored horn (purple or pink), whereas dd individuals have a white horn. You breed two purple horned unicorns to each other (CcDd). Assuming Gene C and Gene D are unlinked, what is the probability that the baby unicorn has a purple horn? Please express your answer to 2 decimal places (e.g. 0.69).arrow_forward
- How can you use this piece of information to help you explain to your friends what is the significance of mutations in the emergence of new genetic properties (alleles) that may result (or not) in new phenotypic characteristics? (Recall that not all SNPs affect phenotype.)arrow_forwardA scientist investigating the genome of two related individuals observes a difference of a few nucleotides in one individual compared to the other. The nucleotide differences are in a region of noncoding DNA on chromosome 1. Would these differences be considered a mutation? Why or why not? Yes, the difference in nucleotide sequences between the individuals is a mutation because it will affect the phenotype of the two individuals. Yes, any heritable variation in the nucleotide sequence is considered a mutation, even if that variation is in a noncoding region of DNA. Not enough information was provided to determine if this nucleotide difference is a mutation because the effect on phenotype is unknown. No, the change in nucleotide sequence doesn't appear in a coding region of the DNA and so can't be a mutation.arrow_forward. In 1932, H. J. Muller suggested a genetic test to determine whether a particular mutation whose phenotypiceffects are recessive to wild type is a null (amorphic)allele or is instead a hypomorphic allele of a gene.Muller’s test was to compare the phenotype of homozygotes for the recessive mutant alleles to the phenotype of a heterozygote in which one chromosomecarries the recessive mutation in question and thehomologous chromosome carries a deletion for aregion including the gene.In a study using Muller’s test, investigators examined two recessive, loss-of-function mutant alleles ofrugose named rg41 and rgγ3. The eye morphologiesdisplayed by flies of several genotypes are indicated inthe following table. Df(1)JC70 is a large deletion thatremoves rugose and several genes to either side of it.Genotype Eye surface Cone cells per ommatidiumwild type smooth 4rg41/rg41 mildly rough 2–3rg41/Df(1)JC70 moderately rough 1–2rg γ3/rg γ3 very rough 0–1rg γ3/Df(1)JC70 very rough 0–1a. Which allele…arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage LearningBiology: The Unity and Diversity of Life (MindTap...BiologyISBN:9781305073951Author:Cecie Starr, Ralph Taggart, Christine Evers, Lisa StarrPublisher:Cengage Learning