Biology XLS7B WEEK 2
Color blindness is a recessive X-linked trait in humans. In a family where the mother is color-blind and the father is normal, the probability of their having a color-blind son is: 0. 1. 1/4. 1/16. 1/2.
1.
The principle of independent assortment holds that: during fertilization, haploid gametes join to create a diploid zygote. the pattern of inheritance of one trait does not influence the pattern of inheritance of another trait. in heterozygotes, the phenotype will be determined by the dominant allele. in heterozygotes, half the gametes will get one allele, and the other half will get the second allele.
the pattern of inheritance of one trait does not influence the pattern of inheritance of another trait.
Consider the pedigree shown below. The trait shown in this pedigree could be autosomal dominant. true false
true
Homologous chromosomes usually have the same arrangement of genes along their length. true false
true
In humans, fruit flies, and many other organisms, most of the genes on the X chromosome are not found on the Y chromosome. false true
true
The genotype of a fetus can be screened for SNPs associated with some diseases. True False
true
Organisms with the genotypes AaBBCcDdEeff and AaBBCcddEeff are crossed. Assuming independent segregation and complete dominance for each trait, what is the expected proportion of the progeny that will be homozygous for all of the genes? 9/16 1/8 0 1/16 1/4
1/16
The maximum frequency of recombination between two genes is: 25%. 0%. 100%. 50% .75%.
50%
Given equal probabilities of the birth of an XY offspring or an XX offspring, what is the probability that a group of four siblings includes all XY offspring? All XX offspring? All XY offspring or all XX offspring? 1/16; 1/16; 1/8 1/16; 1/8; 3/8 1/8; 1/16; 3/8 1/16; 1/16; 1/64
1/16; 1/16; 1/8
Color blindness is a recessive X-linked trait in humans. In a family where the mother is heterozygous for color blindness and the father is color-blind, the probability of their having a color-blind daughter is: 1/4. 0. 1/2. 1/16. 1.
1/2.
The pedigree shown pertains to a trait due to a rare, X-linked recessive mutation. Individual 1 has an affected XY sibling and XY partner, but the genotypes and phenotypes of individuals 1, 3, and 4 are unknown. What is the probability that individual 1 is heterozygous? What is the probability that individual 3 is affected? What is the probability that individual 4 is affected? 1; 1/2; 1/2 1; 1/2; 1/4 1; 1/4; 1/4 1/2; 0; 1/2 1/2; 1/4; 1/4
1/2; 1/4; 1/4 Since this is a rare trait, we can assume that the mother of individual 1 is heterozygous and her father is homozygous for the wild type allele. Individual 1 received an X from the mother, with a 1/2 chance to inherit a mutant allele. If 1 is heterozygous, then there is a 1/2 chance that her daughter, individual 3, inherited the affected X chromosome from her mother and a 100% chance she receives an affected X from her father. The total probability of individual 3 to be affected is 1/2 × 1/2 × 1. For individual 4, there is a 1/2 chance the mother carries an affected X, and a 1/2 chance that she passes it onto her son. The son receives only a Y chromosome from his father. The total probability in this case is 1/2 × 1/2.
Alex and Anna are two people who are considering having children together. Alex, his father (XY parent), and his mother (XX parent) all have blood type B. His younger XX siblings and his XY siblings have blood type O. Anna, her XX parent, and her younger XY sibling all have blood type A. Anna's XX sibling and older XY sibling both have blood type O. Anna's XY parent has type B. What is the probability that Alex and Anna's first offspring will have blood type AB? 1/4 1/3 1/6 1/8
1/3
For most genes on the human X chromosome, what percent of XY males with a mutant allele on the X chromosome will express the mutant phenotype? 50% 0% 25% There is insufficient data to predict. 100%
100%
In genetics, the dash symbol (-) is a "wild card" that stands for either the dominant allele or the recessive allele; for example, A- means the individual has either the genotype AA or Aa. Two genes that undergo independent assortment affect the shape of the seed capsule in the broadleaf weed known as shepherd's purse. Each gene has two alleles, one of which is dominant for the shape of the seed capsule. Genotypes of the form A- B-, A- bb, and aa B- have triangular seed capsules, whereas the seed capsules of aa bb genotypes are ovoid. What ratio of triangular : ovoid is expected from the cross Aa Bb x Aa Bb? 13:3 9:7 10:6 12:4 15:1
15:1 Only the double homozygotes would be ovoid.
In a cross between two individuals who are heterozygous for two traits determined by dominant and recessive alleles (Aa Bb), what is the expected ratio of offspring for the trait determined by the first gene (Aa)? 1:1 12:4:4:1 3:1 9:3:3:1
3:1
In a cross between two individuals who are heterozygous for two traits determined by dominant and recessive alleles (Aa Bb), what is the expected ratio of phenotypes for the traits determined by both genes? 1:1 9:3:3:1 3:1 12:4:4:1
9:3:3:1
What are some reasons why a single trait might not show a 3 : 1 ratio of phenotypes in the F2 generation of a cross between true-breeding strains, and why a pair of traits might not show a 9 : 3 : 3 : 1 ratio of phenotypes in the F2 generation of a cross between true-breeding strains?
A Single trait might not show a 3:1 ratio of phenotypes in the F2 generation of a cross between true-breeding strains because the first trait is affected by more than one gene, or because it is affected by the environment, or because is does not show complete dominance, or because of incomplete penetrance or variable expressivity, or because one phenotype may survive better than the other. Similarly, a pair of traits might not show a 9:3:3:1 ratio of Phenotypes in the F2 generation of a cross between true-breeding strains because the trait is affected by more than two genes, or because it is affected by the environment, or because one or both traits do not show complete dominance, or because of incomplete penetrance or variable expressivity, or ratio, or because some phenotypes may survive better than others.
Why are all the offspring in the F1 generation affected? All gametes produced that combine to make up the F1 generation have the mutant allele. Some of the offspring should be carriers of the mutant allele. Because offspring reflect a mix of the parental phenotypes, all offspring of affected parents are affected. All gametes produced that combine to make up the F1 generation have the mutant allele. It is impossible to have a carrier in the F1 generation. All offspring in the F1 generation will not always be affected; the simulation just hasn't been run enough times to show an alternate outcome.
All gametes produced that combine to make up the F1 generation have the mutant allele. It is impossible to have a carrier in the F1 generation.
Which of the answer choices is a possible human genotype that could result from nondisjunction of the sex chromosomes in one of the parental gametes? All of these choices are correct. XYY XXY XO XXX
All of these choices are correct.
The gene for nose shape is found on the X chromosome. Round nose is dominant to pointed nose. Human individuals with XXY (an additional X chromosome) are designated male. Individuals with XO (only one X chromosome) are designated female. Identify the possible nondisjunction events (rare mistakes during meiosis) that could explain the phenotype of the offspring. An XY parent with a round nose and a XX parent with a round nose have an offspring with Klinefelter Syndrome (genotype XXY) with a pointed nose. C.Nondisjunction could have occurred in meiosis 2 of the XX parent. D.Nondisjunction could have occurred in meiosis 2 of the XY parent. A.Nondisjunction could have occurred in meiosis 1 of the XX parent. B.Nondisjunction could have occurred in meiosis 1 of the XY parent.
C. Nondisjunction could have occurred in meiosis 2 of the XX parent
Flower color in snapdragons is due to a gene with incomplete dominance: CRCR plants have red flowers, CRCW have pink flowers, and CWCW plants have white flowers. Which cross is expected to yield progeny that all have pink flowers? CRCW x CWCW CRCW x CRCW CWCW x CWCW CRCR x CRCW CRCR x CWCW
CRCR x CWCW Mating a homozygous red strain to a homozygous white strain would produce only pink offspring.
Why is the upper limit of recombination 50% rather than 100%?
Even when one or more crossovers occur between the genes, only two of the four products of meiosis are recombinant because crossing over takes place at four- stranded stage of meiosis. With two strands that are recombinant and two strands that are nonrecombinant, the frequency of recombination is 2/4- 50%, and so this is the maximum.
Why are all daughters, but only some sons, affected in the F1 generation? Females pass one of their X chromosomes to their daughters, so all daughters in the F1 will have the disease. Fathers pass on their X chromosome to their daughters, so all daughters in the F1 will have the disease. Females pass one of their X chromosomes to their sons, so at least half of all the sons in the F1 will have the disease. Fathers pass on their X chromosome to their sons, so all of the sons in the F1 will have the disease.
Fathers pass on their X chromosome to their daughters, so all daughters in the F1 will have the disease.
What is the pattern of inheritance expected from a Y-linked gene in a human pedigree?
For Y-linked gene, only males are affected with the trait and all sons of affected males are affected, which means in every generation show the trait. Females never inherit or transmit the trait because females do not have a Y chromosome and males get their Y chromosome from their father.
Which of the statements is true of incomplete penetrance? Incomplete penetrance implies that some individuals will experience less severe forms of disease such as cancer or Alzheimer's. Incomplete penetrance refers to cases in which individuals developing a particular disease (e.g., cancer or Alzheimer's) lack the typical genotype for this disease. Environmental factors do not influence penetrance. For genes with incomplete penetrance some individuals can show the trait while others with the same genotype may not.
For genes with incomplete penetrance some individuals can show the trait while others with the same genotype may not.
Review the pedigree shown and choose the most accurate statement about the inheritance of an X-linked recessive mutation. For recessive X-linked traits, most of the affected individuals are males. For X-linked traits, males only need one copy to express the trait in their phenotype. Females would need two copies of the recessive allele to express the trait in their phenotype. The offspring of an affected male are usually affected. Daughters of affected males are always affected. The brothers of affected males are always affected. The sons of the sisters of affected males will always be affected.
For recessive X-linked traits, most of the affected individuals are males.
A young man wants to determine if he is a descendant of Henry of Navarre and Eleanor of Aquitaine—two of his favorite historical characters. He sends a cheek swab to a DTC company and is offered a choice: the company can assess either the sequence of the man's Y chromosome or his mitochondrial DNA. Which should he choose? It does not matter; an equal amount of genetic variation exists between different Y chromosome haplotypes and different mitochondrial haplotypes. He should get his mitochondrial haplotype sequenced, given the genetic variation in mitochondrial sequences compared to Y chromosomes. He should get his Y chromosome haplotype sequenced, given the robust genetic variation observed across Y chromosomes.
He should get his mitochondrial haplotype sequenced, given the genetic variation in mitochondrial sequences compared to Y chromosomes.
The pedigree shown is following a certain trait that is not Y-linked. Which individuals are expected to have essentially the same Y chromosome? II-1, III-1, and IV-1 All the men in this pedigree should have identical Y chromosomes. I-1, II-7, and III-9 II-5, III-8, and IV-3 I-1, II-5, III-9
II-1, III-1, and IV-1
How can you predict the genotypes and phenotypes of offspring if you know the genotypes of the parents?
If you know the genotypes of the parents, you can determine the alleles that occur in each by applying Mendel's principles of segregation and independent assortment. One systematic approach makes use of the Punnett square, which predicts the probability of every possible combination of one maternal allele with one paternal allele for a particular cross. For example. if a homozygous dominant red parent (RR), were crossed with a homozygous recessive white parent (rr), and R (red) is dominant over r (white), then the offspring predicted by the Punnett square would all have genotype Rr and a phenotype red.
How is it possible that there are multiple different alleles in a population, yet any individual can have only two alleles?
In the population was a whole, there are many copies of each chromosome, so any gene can have multiple alleles present in the different copies. Any one individual can have two copies of any chromosome, so any individual can have no more than two different alleles.
For two genes that show independent assortment, what is the frequency of recombination?
Independent assortment means that a doubly heterozygous genotype such as AB ab produces gametes in the ratio 1/4 AB: 1/4 Ab: 1/4 aB: 1/4 ab. The first and last are nonrecombinant gametes, and the second and the third are recombinant gametes. The frequency of recombination is therefore 1/4+1/4= 1/2, or 50. This means that independent assortment is observed for gametes that are far apart in the same chromosome as well as for genes in different chromosomes.
A carrier is an individual who has an allele associated with a trait but does not display the trait. They are, however, able to pass on the allele to their offspring. When setting the simulation's conditions as described, why does it make no difference whether or not you turn on "show carriers"? All individuals with the disease are also carriers. Individuals with one mutant allele express the disease phenotype and so cannot be carriers. Only individuals with two mutant alleles are affected. Only individuals with two mutant alleles are affected and so there cannot be any carriers for this trait. Individuals with one mutant allele do not express the disease phenotype and so can only be carriers.
Individuals with one mutant allele express the disease phenotype and so cannot be carriers.
Why don't linked genes exhibit independent assortment?
Linked genes do not exhibit independent assortment because they are located sufficiently close together on the same chromosome that crossing over is likely to occur between them and they segregate into gametes together.
What is the biological basis for the 1 : 1 ratio of males and females at conception in mammals?
Meiosis in the mammalian egg cell results in X-bearing eggs only. In contrast, mieosis in the sperm cell results in a 1:1 ratio of X-bearing and Y-bearing cells. Random fertilization of the egg results in a 1:1 ratio of female: male offspring.
What are Mendel's two laws?
Mendel's laws are the principle of segregation and the principle of independent assortment. The principle of segregation states that alleles separate equally into different gametes. The principle of independent assortment states that different gene pairs segregate independently of one another.
How can mitochondrial DNA data be used to trace ancestry?
Mitochondrial DNA does not undergo recombination, so mutations can accumulate in a single line of inheritance, inherited maternally. Because each hereditary lineage of mitochondria is separate from every other lineage mitochondria can be used to trace an individual's ancestry.
The gene for nose shape is found on the X chromosome. Round nose is dominant to pointed nose. Human individuals with XXY (an additional X chromosome) are designated male. Individuals with XO (only one X chromosome) are designated female. Identify the possible nondisjunction events (rare mistakes during meiosis) that could explain the phenotype of the offspring produced by an XY parent with a pointed nose and a XX parent with a round nose have an offspring with Klinefelter Syndrome (genotype XXY) with a pointed nose. Select all that apply. Nondisjunction could have occurred in meiosis 2 of the XX parent. Nondisjunction could have occurred in meiosis 1 of the XX parent. Nondisjunction could have occurred in meiosis 1 of the XY parent. Nondisjunction could have occurred in meiosis 2 of the XY parent.
Nondisjunction could have occurred in meiosis 2 of the XX parent. Nondisjunction could have occurred in meiosis 1 of the XY parent.
Hemophilia is a sex-linked recessive trait in humans. If a carrier XX individual (heterozygous for the trait) mated with a non-affected XY individual, what would be the expected outcome(s)? Select all that apply. None of the offspring would have hemophilia. None of the XX offspring would have hemophilia. Half the XY offspring would have hemophilia. Half the XX offspring would have hemophilia.
None of the XX offspring would have hemophilia. Half the XY offspring would have hemophilia.
A researcher is creating pedigrees for a trait he suspects to be dominant in humans. What are some of the likely features of his pedigrees for families with this trait? Only females will have this dominant trait. All the offspring of a mating where one parent has the trait will themselves be affected. occurrence of mating between individuals with this trait will be high, as all dominant traits are common within any given population. None of the other answer options is correct.
None of the other answer options is correct.
Why is there a higher number of carriers than affected individuals? Offspring inherit alleles from their parents. Since both parents are carriers, the offspring are more likely to be carriers. Offspring have a 50% chance of being a carrier, but only a 25% chance of being affected. Offspring have a 25% chance of being a carrier, and a 50% chance of being affected. Offspring that are homozygous for a recessive trait usually die. Carriers will live, so more of them are present in the pedigree.
Offspring have a 50% chance of being a carrier, but only a 25% chance of being affected.
Why is there a higher number of carriers than affected individuals? Since both parents have disease alleles, all the offspring will inherit at least one mutant allele. Offspring that are homozygous for a recessive trait usually die. Carriers will live, so more of them are present in the pedigree. Offspring have a 75% chance of inheriting at least one mutant allele, but only a 50% chance of having the disease. Offspring have a 75% chance of inheriting at least one mutant allele, but only a 25% chance of having the disease.
Offspring have a 75% chance of inheriting at least one mutant allele, but only a 25% chance of having the disease.
For an individual who is heterozygous for two genes, Aa and Bb, what does independent assortment predict? Offspring inheriting the recessive allele (a) of the first gene will inherit the dominant allele (B) of the second gene. Offspring inheriting the dominant (A) allele of the first gene are equally likely to inherit either the dominant (B) or the recessive (b) allele of the second gene. Offspring inheriting the dominant allele (A) of the first gene will also inherit the dominant (B) allele of the second gene.
Offspring inheriting the dominant (A) allele of the first gene are equally likely to inherit either the dominant (B) or the recessive (b) allele of the second gene.
Why aren't there any affected females in the F1 to F4 generations under these conditions? Only males can be affected because the trait is linked to the Y chromosome. There could be affected females, but the simulation would have to be run many more times. Only males can be affected because they only receive one X chromosome from their mother. Females cannot be affected because the allele is on the inherited paternal X chromosome.
Only males can be affected because the trait is linked to the Y chromosome.
How can the human X and Y chromosomes pair during meiosis even though they are of different lengths and most of their genes are different?
The X and the Y chromosome can pair during meiosis through regions of homology located near the tips of the chromosomal arms
What are some of the benefits and risks of genetic testing and personal genomics?
The benefits of genetic testing include screening for potentially fatal or damaging diseases. For example, certain mutations in the TCF7L2 gene put an individual at an extremely high risk for developing a type two diabetes. If a patient is screened and found to have this mutation, that individual can take preventive measures so that he or she may not necessarily develop diabetes. There are risks involved in genetic testing, however, discrimination of individuals based on genetic information is an issue, especially when it comes to health care.
How can recombination frequency be used to build a genetic map?
The closer, or more tightly linked, that two genes are to each other, the smaller the frequency of recombination because it is less likely that a crossover event would take place in the interval between them. The further away two genes are from each other, the greater the frequency of recombination because there would be a greater chance that a crossover event will happen in the interval between the genes. The frequency of recombination can be used as a measure of distance between the genes.
Construct a human pedigree for a dominant trait and a recessive trait. What are the patterns of inheritance in each?
The fist pedigree displays a recessive trait. It is revealed as a recessive because it does not occur every generation, and because two nonaffected individuals have two affected children. The second pedigree displays a dominant trait. That is revealed as a dominant because it appears in every generation and affects about half of the offspring.
A man affected with a mitochondrial disease mates with a woman who does not have a mitochondrial disease. What is the probability that their offspring will be affected?
The offspring will likely not be affected by a mitochondrial disease because mitochondria of the offspring come from the mother, not the father
Which of the answer choices is true of a cross involving a sex-linked gene (one on the X or Y chromosome) but not of a cross involving an autosomal gene? Only autosomal genes observe the law of segregation. Recombination, or crossing over, cannot take place between the X and Y chromosomes. The phenotype outcomes of XX offspring and XY offspring can be different. A Punnett square cannot be utilized for illustrating the possible outcomes of a cross involving a sex-linked gene. Both parents have two copies of a sex-linked gene.
The phenotype outcomes of XX offspring and XY offspring can be different.
How do the mechanics of meiosis and the movement of homologous chromosomes underlie Mendel's principles of segregation and independent assortment?
The segregation of alleles reflects the separation of chromosomes in meiosis. Homologous chromosomes separate during anaphase 1 of meiosis 1, leading to the segregation of alleles. Chromosomes display independent assortment during meiosis when they are sorted into daughter cells randomly.
Why aren't there any affected females in the F1 generation under these conditions? The recessive allele is less likely to be inherited than the mutant allele. X-linked traits are only seen in males. Only males can be affected because the trait is X-linked recessive. There is only one affected allele segregating in the pedigree.
There is only one affected allele segregating in the pedigree.
When a 9:3:3:1 ratio of phenotypes is produced by a cross between two individuals, which phenotypes are present in the rarest class that is represented by only 1 of the 16 possible genotypes of offspring? These offspring have the dominant phenotype of one trait and the recessive phenotype of the other trait. These offspring have the dominant phenotype of both traits. These offspring have the recessive phenotype of both traits.
These offspring have the recessive phenotype of both traits.
After doing PCR on the same region between two individuals, you notice that each person's DNA yielded pieces of different sizes. Which of the following is the MOST likely explanation? A mistake was made during the PCR.A mistake was made during gel electrophoresis. This is an example of RFLPs. None of the answer options is correct. This is an example of VNTRs.
This is an example of VNTRs.
Imagine that a doctor sees a patient that is genotypically male, but is phenotypically female. How could this occur? This patient likely carries a mutation in SRY that increases SRY protein levels, and a mutation in the X chromosome that decreases X chromosome-associated protein levels. This patient likely carries a mutation in the X chromosome that increases X chromosome-associated protein levels. This patient likely carries a mutation in SRY that increases SRY protein levels. This patient likely carries a mutation in the X chromosome that decreases X chromosome-associated protein levels. This patient likely carries a mutation in SRY that decreases SRY protein levels. The SRY gene codes for protein necessary for male development. A mutation in this gene can result in phenotypically female XY individuals.
This patient likely carries a mutation in SRY that decreases SRY protein levels.
Why aren't there any affected individuals in the F1 generation? One recessive allele is required to express the phenotype, and F1 individuals only have a 50% chance of inheriting the mutant allele. Two recessive alleles are required to express the phenotype, and F1 individuals always marry individuals that are not affected. Two recessive alleles are required to express the phenotype, and F1 individuals always receive one nonmutant allele from the unaffected parent. One recessive allele is required to express the phenotype, and F1 individuals that are the same sex as the affected parent have a 50% chance of inheriting the mutant allele.
Two recessive alleles are required to express the phenotype, and F1 individuals always receive one nonmutant allele from the unaffected parent.
For a recessive X-linked mutation, such as color blindness, what is the pattern of inheritance from an affected male through his daughters into her children?
When an affected male mates with a homozygous non mutant female, all of the sons are normal (because they receive their X chromosome from their mother), but all of the daughters are heterozygous ( because they must receive their father's X chromosome). When one of these heterozygous daughters mates with a normal male, half of these sons are affected ( they inherit their grandfather's X-linked allele) and half are normal (they inherit their grandmother's X-linked allele); as for the daughters, although all of the daughters are phenotypically unaffected, half are heterozygous (they inherit their grandfather's X-linked allele), whereas half are homozygous nonmutant (they inherit their grandmother's X-linked allele).
Is it possible for an unaffected female to have female offspring with red-green color blindness?
Yes. A woman whose father is color blind must be heterozygous for the mutant allele. If she has children with a man who is color blind, then half of the female offspring are expected to be heterozygous mutant and therefore color blind.
In crosses involving linked genes, recombinant offspring result from: sex-linked inheritance. Mendelian segregation. Mendelian segregation and independent assortment of alleles. a crossover. independent assortment of alleles.
a crossover.
The Y-linked trait of hairy ears has been passed down for many generations in a certain family. A hairy-eared male in this family would be expected to have: nephews with hairy ears. a paternal grandfather with hairy ears. male and female grandchildren with hairy ears. a maternal grandfather with hairy ears. uncles with hairy ears.
a paternal grandfather with hairy ears.
If an XY male carries a mutation on his X chromosome, _______________ will receive the mutant X. all his sons and daughters half his sons and half his daughters all of his sons all of his daughters
all of his daughters
The principle of independent assortment states that: when gametes are formed, the two members of a gene pair will separate equally into gametes. one set of alleles of a gene pair always assorts with the alleles of another gene pair. when gametes are formed, the two members of a gene pair assort together in gametes. alleles of a gene pair assort independently of other gene pairs. alleles of a gene pair assort independently of other gene pairs.
alleles of a gene pair assort independently of other gene pairs.
Genes located along the X chromosome: have a full set of complementary alleles on the Y chromosome. are called X-linked genes. are always recessive to genes located on the Y chromosome. are contributed solely by the female parent.
are called X-linked genes.
Genes in different chromosomes _____ during meiosis. Genes that are very close together in the same chromosome are _____. do not assort independently; unrelated assort independently; not assort independently; linked assort independently; linked
assort independently; linked
A researcher discovers a new type of plant. After setting up several crosses, she assesses the mitochondrial sequences in the F1 generations and compares these to the mitochondrial sequences in the parental generation. In the progeny, she finds sequences that are similar to both the maternal and paternal sequences in the parental generation. These plants demonstrate _____ inheritance of their organelles. recombinant maternal random paternal biparental In plants, mitochondria can be inherited from either parent.
biparental
A heterozygous female harboring one mutant allele for hemophilia is called a(n) _____ for that trait. carrier harborer affected female contributor messenger
carrier
Refer to Animation: Linkage and Recombination. Which of the statements is least likely to produce recombinant chromosomes? crossovers between homologous chromosomes crossovers between non-sister chromatids crossovers between sister chromatids
crossovers between sister chromatids
You are examining a human pedigree for a trait. You notice that the trait appears in every generation, is equally likely to occur in males and females, and about half of the offspring are affected when one parent is affected. The trait is most likely: recessive. that shows incomplete penetrance. dominant. epistatic. produced by multiple alleles.
dominant.
Which of the statements are false for this image? chromosomes containing the same genes but different alleles of the genes. duplicated homologous chromosomes. homologous chromosomes. chromosomes containing the same genes. duplicated nonhomologous chromosomes.
duplicated nonhomologous chromosomes.
When one gene is able to modify the effect of a second gene, the phenomenon is known as: simple dominance. segregation. recessiveness .independent assortment. epistasis.
epistasis.
All organisms have either an X or Y chromosome, as these chromosomes are solely responsible for determining the sex of an individual. true false
false
Consider the pedigree shown below. The trait shown in the pedigree could be X-linked recessive. true false
false
During meiosis in female mammals, sex chromosomes segregate to produce two types of eggs: X-bearing eggs and Y-bearing eggs. true false
false
Physical exchange between homologous chromosomes (crossover) occurs during metaphase I of meiosis. true false
false
The pedigree below shows the inheritance of fur color in Bruins. Fur color in Bruins is determined by a single autosomal gene with three alleles (blue, gold, and white) that exhibit an unknown hierarchy of dominance. Genetic testing shows that individuals I-1 and III-4 are each homozygous for one allele. Use this information and the pedigree to answer the following questions. II-5 and II-6 are more likely to have a white Bruin than a gold Bruin true false
false
The pedigree below shows the inheritance of fur color in Bruins. Fur color in Bruins is determined by a single autosomal gene with three alleles (blue, gold, and white) that exhibit an unknown hierarchy of dominance. Genetic testing shows that individuals I-1 and III-4 are each homozygous for one allele. Use this information and the pedigree to answer the following questions. The gold allele is dominant to the white allele True False
false
An individual is heterozygous for two linked genes, but whether its genotype is AB/ab or Ab/aB is not known. The individual is crossed with an ab/ab individual, and among the progeny are: 16 AB/ab; 54 Ab/ab; 46 aB/ab; 24 ab/ab.These results imply that the genotype of the doubly heterozygous parent was AB/ab. false true
false The recombinant (non-parental) chromosomes occur in smaller frequencies than the non-recombinant (parental) chromosomes in matings where two genes are linked on the same chromosome.
he _____________ two loci are on a chromosome, the more likely they will be separated by crossover events during gamete formation, and thus the frequency of recombination between loci on a chromosome can be used to measure the _______________ between those loci. closer together; genetic distance farther apart; genetic distance closer together; number of crossovers farther apart; number of crossovers
farther apart; genetic distance
The graphs shown depict the relative proportions of individuals affected with a certain condition (darker shaded bar) and individuals not affected (lighter bar), in individuals carrying either the A - T or the G - C allele of a single-nucleotide polymorphism (SNP). Heterozygous genotypes carry both alleles and are included in both categories. Which graph shows a pattern that suggests that the G - C allele is a risk factor for the disease? graph M graph H graph L graph Q graph K
graph L
A normal female who carries a recessive X-linked allele for hemophilia will pass it on to: all of her sons. all of her daughters. half of her sons. half of both her sons and daughters. half of her daughters.
half of both her sons and daughters.
The mitochondrial DNA sequences of a large extended family were analyzed and compared to a single male in the family. Which of the relatives' mitochondrial DNA should be a match to this person? his brother's daughter his paternal grandmother his maternal grandfather his children his sister's son Mitochondrial DNA are passed from the mother to offspring. A male in the family will share the same mtDNA as his sister, and the sister would have passed on the same mtDNA to her son.
his sister's son
Hairy cell leukemia is a cancer of the white blood cells that respond to treatment with drugs that inhibit DNA synthesis. A mutation in the BRAF gene, designated BRAF V600E, is associated with hairy cell leukemia. BRAF V600E differs from the nonmutant BRAF gene in a single base pair. Imagine that this change to the single base-pair added a Hae III restriction site indicated by the arrow on the gene below. You decide to identify hairy cell leukemia with PCR and the restriction enzyme Hae III. which lane on the gel represents DNA from cells heterozygous for the BRAF V600E allele? lane 1 lane 2 lane 4 lane 3
lane 2 The heterozygote has three bands: the biggest one from the nonmutant allele and two smaller bands resulting from the cut at the additional Hae III site
Hairy cell leukemia is a cancer of the white blood cells that responds to treatment with drugs that inhibit DNA synthesis. A mutation in the BRAF gene, designated BRAF V600E, is associated with hairy cell leukemia. BRAF V600E differs from the nonmutant BRAF gene in a single base pair. Imagine that this change to the single base-pair added a Hae III restriction site indicated by the arrow on the gene below. You decide to identify hairy cell leukemia with PCR and the restriction enzyme Hae III. Which lane in the gel represents an individual who is homozygous for the Hae III restriction site? lane 2 lane 3 lane 4 lane 1
lane 3 The homozygote for the BRAF V600E allele has two bands since both alleles have an additional Hae III site
A mutation with a deleterious effect on the function of a protein encoded by a human mitochondrial gene will be: autosomally inherited. paternally inherited. X-linked. maternally inherited.
maternally inherited.
During which phase of meiosis do homologous chromosomes synapse with crossing-over between homologous chromosomes? neither prophase I nor prophase II both prophase I and prophase II prophase I prophase II
prophase I
While doing a pedigree analysis of a European royal family, you notice a disease in a female child of two healthy parents. There are also some cousins with the same genetic disease. If this disease is controlled by a single gene, then the most likely explanation for these observations is the disease is: recessive and only seen in homozygous recessive individuals such as the daughter. dominant and is seen in homozygous dominant or heterozygous individuals. dominant and only seen in homozygous dominant individuals such as the daughter. only seen in heterozygous individuals such as the daughter. a spontaneous mutation.
recessive and only seen in homozygous recessive individuals such as the daughter.
Mutations that destroy or create a cleavage site for a restriction enzyme are the source of: restriction fragment length polymorphisms. variable number tandem repeats. single-nucleotide polymorphisms. copy-number variants.
restriction fragment length polymorphisms.
Genes that are close together in the same chromosome: tend to assort independently. are present only in the X chromosomes. tend to be transmitted together and are present only in X chromosomes. usually assort independently, but very rarely will be transmitted together. tend to be transmitted together.
tend to be transmitted together.
The tips of the arms of the X and Y chromosomes share small regions of homology. Genes located in these regions are inherited in the same manner as the ones found in autosomes. true false
true
This image shows a pair of linked genes with alleles A and B linked on one of the homologues and alleles a and b linked on the other. false true
true
Without the SRY gene, humans and other mammals would develop and retain the female sex organs and phenotype. true false
true
Two genes, A and B, are found on the same chromosome. One chromosome has alleles A and B, while its homolog has alleles a and b. If genes A and B are so closely linked that the recombination frequency is 0 percent, only AB and ab gametes will be produced during meiosis. false true
true If two genes are physically located very close to each other on the chromosome, then recombination cannot occur and only non-recombinant gametes will be produced.
A doctor is presented with a patient complaining of persistent muscle weakness. The patient mentions this is something that all of her children also experience, as did her mother when she was alive. This family may be suffering from a mitochondrial disease. true false
true Mitochondria are the site of ATP synthesis, and thus provide the chemical energy necessary for many cellular processes including true muscular contraction.
How can Y-chromosome data can be used to trace ancestry?
y-linked genes show complete linkage, which means that sequences in the Y chromosome are not exchanged for others through crossing over and mutations can accumulate in a single line inheritance. Because each heredity lineage of Y chromosomes is separate from every other lineage, they can be used to trace an individual's ancestry.
