All Related Questions of Allele

Q: What is a reciprocal cross? Suppose that a gene is found

What is a reciprocal cross? Suppose that a gene is found as a wildtype (functional) allele and a recessive mutant (nonfunctional) allele. What would be the expected outcomes of reciprocal crosses if a...

Q: Explain the relationship between each of the following pairs of genetic terms

Explain the relationship between each of the following pairs of genetic terms: A. Gene and trait B. Gene and chromosome C. Allele and gene D. DNA sequence and amino acid sequence

Q: Female fruit flies homozygous for the X-linked white-eye

Female fruit flies homozygous for the X-linked white-eye allele are crossed to males with red eyes. On very rare occasions, an offspring of such a cross is a male with red eyes. Assuming these rare of...

Q: A human gene called the β-globin gene encodes a polypeptide

A human gene called the β-globin gene encodes a polypeptide that functions as a subunit of the protein known as hemoglobin. Hemoglobin is found within red blood cells; it carries oxygen. In human popu...

Q: Identical twins are produced from the same sperm and egg (which

Identical twins are produced from the same sperm and egg (which splits after the first mitotic division), whereas fraternal twins are produced from separate sperm and separate egg cells. If two parent...

Q: In humans, the allele for brown eye color (B)

In humans, the allele for brown eye color (B) is dominant to that for blue eye color (b). If two heterozygous parents produce children, what are the following probabilities? A. The first two children...

Q: Based on genes in pea plants that we have considered in this

Based on genes in pea plants that we have considered in this chapter, which statement(s) is/are not correct? A. The gene causing tall plants is an allele of the gene causing dwarf plants. B. The gen...

Q: In Shorthorn cattle, coat color is controlled by a single gene

In Shorthorn cattle, coat color is controlled by a single gene that can exist as a red allele (R) or a white allele (r). The heterozygotes (Rr) have a color called roan that looks less red than the RR...

Q: In chickens, the Leghorn variety has white feathers due to an

In chickens, the Leghorn variety has white feathers due to an autosomal dominant allele. Silkies have white feathers due to a recessive allele in a second (different) gene. If a true-breeding white Le...

Q: In rabbits, the color of body fat is controlled by a

In rabbits, the color of body fat is controlled by a single gene with two alleles, designated Y and y. The outcome of this trait is affected by the diet of the rabbit. When raised on a standard vegeta...

Q: In cats, a temperature-sensitive allele produces the Siamese phenotype

In cats, a temperature-sensitive allele produces the Siamese phenotype, in which the cooler extremities are dark and the warmer trunk area is lighter. A Siamese cat that spends most of its time outsid...

Q: In humans, a very rare dominant allele that causes the little

In humans, a very rare dominant allele that causes the little finger to be crooked has a penetrance of 80%. In other words, 80% of heterozygotes carrying the allele will have a crooked little finger....

Q: A sex-influenced trait in humans affects the length of the

A sex-influenced trait in humans affects the length of the index finger. A short allele is dominant in males and recessive in females. Heterozygous males have an index finger that is significantly sho...

Q: Let’s suppose a recessive allele encodes a completely defective protein. If

Let’s suppose a recessive allele encodes a completely defective protein. If the functional allele is dominant, what does that tell you about the amount of the functional protein that is sufficient to...

Q: A nectarine is a peach without the fuzz. The difference is

A nectarine is a peach without the fuzz. The difference is controlled by a single gene that is found in two alleles, D and d. At the molecular level, do you think that the nectarine is homozygous for...

Q: An allele in Drosophila produces a star-eye trait in the

An allele in Drosophila produces a star-eye trait in the heterozygous individual. However, the star-eye allele is lethal in homozygotes. What would be the ratio of phenotypes of surviving offspring if...

Q: A maternal effect gene exists in a dominant N (functional)

A maternal effect gene exists in a dominant N (functional) allele and a recessive n (nonfunctional) allele. What would be the ratios of genotypes and phenotypes for the offspring of the following cros...

Q: A Drosophila embryo dies during early embryogenesis due to a recessive maternal

A Drosophila embryo dies during early embryogenesis due to a recessive maternal effect allele called bicoid−. The wild-type allele is designated bicoid+. What are the genotypes and phenotypes of the e...

Q: For Mendelian inheritance, the nuclear genotype (i.e.,

For Mendelian inheritance, the nuclear genotype (i.e., the alleles found on chromosomes in the cell nucleus) directly influences an offspring’s traits. In contrast, for non-Mendelian inheritance patte...

Q: Suppose a maternal effect gene exists as a functional dominant allele and

Suppose a maternal effect gene exists as a functional dominant allele and a nonfunctional recessive allele. A mother who is phenotypically abnormal produces all normal offspring. Explain the genotype...

Q: In Drosophila, an allele causing vestigial wings is 12.5

In Drosophila, an allele causing vestigial wings is 12.5 mu away from another allele that causes purple eyes. A third gene that affects body color has an allele that causes black body color. This thir...

Q: Let’s suppose that two different X-linked genes exist in mice

Let’s suppose that two different X-linked genes exist in mice, designated with the letters N and L. Gene N exists in a dominant, normal allele and in a recessive allele, n, that is lethal. Similarly,...

Q: A recessive allele in mice results in an unusally long neck.

A recessive allele in mice results in an unusally long neck. Sometimes, during early embryonic development, the long neck causes the embryo to die. An experimenter began with a population of true-bree...

Q: What features of this pedigree indicate that the allele for Duchenne muscular

What features of this pedigree indicate that the allele for Duchenne muscular dystrophy is X-linked? From Figure 4.10:

Q: Let’s suppose that you have made a karyotype of a female fruit

Let’s suppose that you have made a karyotype of a female fruit fly with red eyes and found that it has three X chromosomes instead of the normal two. Although you do not know its par...

Q: In a species of plant, two genes control flower color.

In a species of plant, two genes control flower color. The red allele (R) is dominant to the white allele (r); the color-producing allele (C) is dominant to the non-color-producing allele (c). You sus...

Q: Red eyes is the wild-type phenotype in Drosophila, and

Red eyes is the wild-type phenotype in Drosophila, and several different genes (with each gene existing in two or more alleles) affect eye color. One allele causes purple eyes, and a different allele...

Q: In sheep, the formation of horns is a sex-influenced

In sheep, the formation of horns is a sex-influenced trait; the allele that results in horns is dominant in males and recessive in females. Females must be homozygous for the horned allele to have hor...

Q: Chapter 21 describes a blotting method known as Northern blotting that is

Chapter 21 describes a blotting method known as Northern blotting that is used to determine the amount of mRNA produced by a particular gene. In this method, the amount of a specific mRNA produced by...

Q: As mentioned in Experimental Question E11, red eyes is the wildtype

As mentioned in Experimental Question E11, red eyes is the wildtype phenotype. Several different genes (with each gene existing in two or more alleles) are known to affect eye color. One allele causes...

Q: Let’s suppose you were looking through a vial of fruit flies in

Let’s suppose you were looking through a vial of fruit flies in your laboratory and noticed a male fly with pink eyes. What crosses would you make to determine if the pink allele is an X-linked gene?...

Q: Figure 5.6 describes the results of X-chromosome inactivation

Figure 5.6 describes the results of X-chromosome inactivation in mammals. If fast and slow alleles of glucose-6-phosphate dehydrogenase (G-6-PD) exist in other species, what would be the expected resu...

Q: In the experiment of Figure 5.6, why does a

In the experiment of Figure 5.6, why does a clone of cells produce only one type of G-6-PD enzyme? What would you expect to happen if a clone was derived from an early embryonic cell? Why does the ini...

Q: Let’s suppose a gene exists as a functional wild-type allele

Let’s suppose a gene exists as a functional wild-type allele and a nonfunctional mutant allele. At the organism level (i.e., at the level of visible traits), the wild-type allele is dominant. In a het...

Q: In mice, a dominant allele that causes a short tail is

In mice, a dominant allele that causes a short tail is located on chromosome 2. On chromosome 3, a recessive allele causing droopy ears is 6 mu away from another recessive allele that causes a flaky t...

Q: Which allele is an example of a loss-of-function

Which allele is an example of a loss-of-function allele?

Q: On the left side of this figure, explain why the offspring

On the left side of this figure, explain why the offspring TABLE 5.2 does not have Prader-Willi syndrome but does have Angelman syndrome. From Table 5.2:

Q: Explain why the HbS allele is prevalent in certain regions even though

Explain why the HbS allele is prevalent in certain regions even though it is detrimental in the homozygous condition.

Q: Two techniques commonly used to study the expression patterns of genes that

Two techniques commonly used to study the expression patterns of genes that play a role in development are Northern blotting and in situ hybridization. As described in Chapter 21, Northern blotting is...

Q: Among a large population of 2 million gray mosquitoes, one mosquito

Among a large population of 2 million gray mosquitoes, one mosquito is heterozygous for a body color gene; this mosquito has one gray allele and one blue allele. There is no selective advantage or dis...

Q: In a donor population, the allele frequencies for the common (

In a donor population, the allele frequencies for the common (HbA ) and sickle cell (HbS ) alleles are 0.9 and 0.1, respectively. A group of 550 individuals from this population migrates to another po...

Q: You will need to refer to question 2 in More Genetic TIPS

You will need to refer to question 2 in More Genetic TIPS to answer this question. The gene for coat color in rabbits can exist in four alleles termed C (full coat color), cch (chinchilla), c h (Himal...

Q: The human MN blood group is determined by two codominant alleles,

The human MN blood group is determined by two codominant alleles, M and N. The following data were obtained from five human populations: A. Calculate the allele frequencies in these five populations....

Q: Resistance to the poison warfarin is a genetically determined trait in rats

Resistance to the poison warfarin is a genetically determined trait in rats. Homozygotes carrying the resistance allele (WR WR ) have a lower fitness because they suffer from vitamin K deficiency, but...

Q: A recessive lethal allele has achieved a frequency of 0.22

A recessive lethal allele has achieved a frequency of 0.22 due to genetic drift in a very small population. Based on natural selection, how would you expect the allele frequencies to change in the nex...

Q: Achondroplasia is a rare form of dwarfism caused by an autosomal dominant

Achondroplasia is a rare form of dwarfism caused by an autosomal dominant mutation that affects the gene that encodes a fibroblast growth factor receptor. Among 1,422,000 live births, the number of ba...

Q: Sandhoff disease is due to a mutation in a gene that encodes

Sandhoff disease is due to a mutation in a gene that encodes a protein called hexosaminidase B. This disease has symptoms that are similar to those of Tay-Sachs disease. Weakness begins in the first 6...

Q: We often speak of diseases such as phenylketonuria (PKU) and

We often speak of diseases such as phenylketonuria (PKU) and achondroplasia as having a genetic basis. Explain whether the following statements are accurate with regard to the genetic basis of any hum...

Q: What would you predict to be the phenotype of a Drosophila larva

What would you predict to be the phenotype of a Drosophila larva whose mother was homozygous for a loss-of-function allele in the nanos gene?

Q: What evolutionary factors can cause allele frequencies to change and possibly lead

What evolutionary factors can cause allele frequencies to change and possibly lead to a genetic polymorphism? Discuss the relative importance of each type of process.

Q: Why is genetic drift more significant in small populations? Why does

Why is genetic drift more significant in small populations? Why does it take longer for genetic drift to cause allele fixation in large populations than in small ones?

Q: A group of four birds flies to a new location and initiates

A group of four birds flies to a new location and initiates a new colony. Three of the birds are homozygous AA, and one bird is heterozygous Aa. A. What is the probability that the a allele will beco...

Q: Describe what happens to allele frequencies as a result of the bottleneck

Describe what happens to allele frequencies as a result of the bottleneck effect. Discuss the relevance of this effect with regard to species that are approaching extinction.

Q: With regard to genetic drift, are the following statements true or

With regard to genetic drift, are the following statements true or false? If a statement is false, explain why. A. Over the long run, genetic drift leads to allele fixation or loss. B. When a new mu...

Q: When two populations frequently intermix due to migration, what are the

When two populations frequently intermix due to migration, what are the long-term consequences with regard to allele frequencies and genetic variation?

Q: Two populations of antelope are separated by a mountain range. The

Two populations of antelope are separated by a mountain range. The antelope are known to occasionally migrate from one population to the other. Migration can occur in either direction. Explain how mig...

Q: Does inbreeding affect allele frequencies? Why or why not? How

Does inbreeding affect allele frequencies? Why or why not? How does it affect genotype frequencies? With regard to rare recessive diseases, what are the consequences of inbreeding in human populations...

Q: Identify each of the following as an example of allele, genotype

Identify each of the following as an example of allele, genotype, and/or phenotype frequency: A. Approximately 1 in 2500 people of Northern European descent is born with cystic fibrosis. B. The perc...

Q: For a gene existing in two alleles, what are the allele

For a gene existing in two alleles, what are the allele frequencies when the heterozygote frequency is at its maximum value, assuming Hardy-Weinberg equilibrium? What if there are three alleles?

Q: The ability to roll your tongue is inherited as a recessive trait

The ability to roll your tongue is inherited as a recessive trait. The frequency of the rolling allele is approximately 0.6, and that of the dominant (nonrolling) allele is 0.4. What is the frequency...

Q: Let’s suppose that weight in a species of mammal is polygenic,

Let’s suppose that weight in a species of mammal is polygenic, and each gene exists as a heavy and light allele. If the allele frequencies in the population are equal for both types of alleles (i.e.,...

Q: In the F1 offspring, what happened to the B-I

In the F1 offspring, what happened to the B-I allele that was inherited from the parent at the top right?

Q: Antibiotics are commonly used to combat bacterial and fungal infections. During

Antibiotics are commonly used to combat bacterial and fungal infections. During the past several decades, however, antibioticresistant strains of microorganisms have become alarmingly prevalent. This...

Q: Let’s suppose the mutation rate for converting a B allele into a

Let’s suppose the mutation rate for converting a B allele into a b allele is 10–4. The current allele frequencies are B = 0.6 and b = 0.4. How long will it take for the allele frequencies to equal eac...

Q: A human gene, which we will call gene X, is

A human gene, which we will call gene X, is located on chromosome 11 and is found as a normal allele and a recessive disease causing allele. The location of gene X has been approximated on the map sho...

Q: Discuss the role of mutation in the origin of genetic polymorphisms.

Discuss the role of mutation in the origin of genetic polymorphisms. Suppose that a genetic polymorphism involves two alleles at frequencies of 0.45 and 0.55. Describe three different scenarios to exp...

Q: In the experiments described in Figure 16.8, explain the

In the experiments described in Figure 16.8, explain the relationship between coat color and DNA methylation. How is coat color related to the diet of the mother? From Figure 16.8:

Q: Look back at Figure 16.7. If you crossed an

Look back at Figure 16.7. If you crossed an F2 offspring to a homozygous B-I B-I plant, what phenotypic results would you expect for the F3 offspring? From Figure 16.7:

Q: Gerald Rubin and Allan Spradling devised a method of introducing a transposon

Gerald Rubin and Allan Spradling devised a method of introducing a transposon into Drosophila. This approach has been important for the transposon tagging of many Drosophila genes. The researchers beg...

Q: Researchers have identified a gene in humans that (when mutant)

Researchers have identified a gene in humans that (when mutant) causes severe dwarfism and mental impairment. This disorder is inherited in an autosomal recessive manner, and the mutant allele is know...

Q: Let’s suppose an X-linked gene in mice exists as two

Let’s suppose an X-linked gene in mice exists as two alleles, which we will call B and b. X-chromosome inactivation, a process in which one X chromosome is turned off, occurs in the somatic cells of f...

Q: Explain what happened to the b allele that allowed gene conversion to

Explain what happened to the b allele that allowed gene conversion to occur.

Q: Chapter 21 describes a method known as Western blotting that can be

Chapter 21 describes a method known as Western blotting that can be used to detect a polypeptide that is translated from a particular mRNA. In this method, a particular polypeptide or protein is detec...

Q: AFTER malaria is cured, the frequency of the HbS allele should

AFTER malaria is cured, the frequency of the HbS allele should decrease in regions with lots of mosquitoes because: People will no longer die from sickle-cell anemia in these regions. Having one copy...

Q: An allele is an alternate form of a gene, and the

An allele is an alternate form of a gene, and the proportion of alleles in a population is of interest in genetics. An article in BMC Genetics [“Calculating Expected DNA Remnants from Ancient Founding...

Q: Cells lining the epididymis secrete a glycoprotein (beta-defensin)

Cells lining the epididymis secrete a glycoprotein (beta-defensin) that coats sperm and facilitates their passage through cervical mucus. There are two common alleles for human beta-defensin: a wild-t...

Q: Cells lining the epididymis secrete a glycoprotein (beta-defensin)

Cells lining the epididymis secrete a glycoprotein (beta-defensin) that coats sperm and facilitates their passage through cervical mucus. There are two common alleles for human beta-defensin: a wild-t...

Q: Cells lining the epididymis secrete a glycoprotein (beta-defensin)

Cells lining the epididymis secrete a glycoprotein (beta-defensin) that coats sperm and facilitates their passage through cervical mucus. There are two common alleles for human beta-defensin: a wild-t...

Q: Cells lining the epididymis secrete a glycoprotein (beta-defensin)

Cells lining the epididymis secrete a glycoprotein (beta-defensin) that coats sperm and facilitates their passage through cervical mucus. There are two common alleles for human beta-defensin: a wild-t...

Q: A gene is composed of two alleles, either dominant or recessive

A gene is composed of two alleles, either dominant or recessive. Suppose that a husband and wife, who are both carriers of the sickle-cell anemia allele but do not have the disease, decide to have a c...

Q: In Problem 29, we learned that for some diseases, such

In Problem 29, we learned that for some diseases, such as sickle-cell anemia, an individual will get the disease only if he or she receives both recessive alleles. This is not always the case. For exa...