Genetics2 Probability2 Quiz
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Father has a trait, which is inherited in autosomal recessive mode of inheritance. Calculate the probability to have a son with a trait in marriage with a female who is a carrier of recessive allele.

  • 1
  • 1/2
  • 1/4 (correct)
  • 0

    • What is a Barr body?

  • An inactivated Y-chromosome found in males
  • An inactivated X-chromosome found in males
  • An inactivated X-chromosome found in females (correct)
  • A type of protein found exclusively in flies

    • A large, three generation family in whom multiple members are affected with a rare, undiagnosed disease is being studied. Affected males never produce affected children, but affected females do produce affected children of both sexes when mate with unaffected males. What is the most likely mode of inheritance?

  • Mitochondrial (correct)
  • X linked recessive
  • Autosomal dominant, with expression limited to females
  • Y linked

    • Neurofibromatosis type 1 is one of the most common autosomal dominant disorders. A heterozygous woman with neurofibromatosis type 1 has an unaffected partner. Which of the following is correct regarding their children?

    <p>The probability that their third child will be affected if their first two children are affected is 1 in 2.</p> Signup and view all the answers

    The characteristic indicated by the blackened figures is probably:

    both parents and children affected

    <p>Dominant</p> Signup and view all the answers

    The pedigree chart below is for a family, some of whose members exhibit the autosomal dominant trait, brown eye color. Brown eyed individuals are indicated by a dark square or circle. Use the chart to answer the following question: what is the probability that individual D-3 is Ww?

    <p>1</p> Signup and view all the answers

    A man who is affected with hemophilia A (X linked recessive) mates with a woman who is a heterozygous carrier of this disorder. What proportion of the couple's daughters will be affected, and what proportionof the daughters will be heterozygous carriers?

    <p>50%;50%</p> Signup and view all the answers

    In a certain population, the frequency of color-blind males is 1 in 100. Assuming that the population is in Hardy-Weinberg eqiulibrium at this locus, the frequency of color-blind females is approximately

    <p>0,0001</p> Signup and view all the answers

    In humans an extra copy of chromosome 21 typically leads to moderate to severe mental retardation and sterility, as well as a greater likelihood of heart defects and other problems. This disorder is known as ____.

    <p>Down syndrome</p> Signup and view all the answers

    Down syndrome is the result of:

    <p>Additional chromosome 21</p> Signup and view all the answers

    Which genetic condition is revealed in the photos above?

    <p>Down syndrome</p> Signup and view all the answers

    Fraternal (dizygotic) twins are produced when:

    <p>Two eggs are fertilized simultaneously</p> Signup and view all the answers

    Which of the following conditions are required for a population to be in HardyWeinberg equilibrium?

    <p>All of these are conditions of Hardy-Weinberg equilibrium</p> Signup and view all the answers

    Cystic fibrosis is an autosomal recessive disease. In a population of one hundred individuals, twenty-five are found to have the disease. Assuming Hardy-Weinberg equilibrium, what is the percent of the population that are carriers for cystic fibrosis?

    <p>50%</p> Signup and view all the answers

    75% of a given population test positive for Rhesus (Rh) factor. Given that blood type Rh is a dominant allele, what percentage of this population is homozygous?

    <p>25%</p> Signup and view all the answers

    Identical twins can result from:

    <p>a division of a zygote into two separate cells that develop into two separate embryos</p> Signup and view all the answers

    The change in the chromosome depicted in the figure above represents a(n) ____. chrosome change place

    <p>duplication</p> Signup and view all the answers

    Nondisjunction in Meiosis I results in

    <p>one pole of the cell receiving neither member of a homologous pair of chromosomes</p> Signup and view all the answers

    which genetic condition is revealed on the photo below? bild på en bebis problem med ansiktet

    <p>Patau syndrome</p> Signup and view all the answers

    Which genetic condition is revealed in the karyotype display shown in the figure above?

    bild på genokaryt

    <p>Patau syndrome</p> Signup and view all the answers

    The polymerase chain reaction or PCR is a technique that

    <p>uses short DNA primers and a thermostable DNA polymerase to replicate specific DNA sequences in vitro</p> Signup and view all the answers

    On the following pedigree what is the genotype of the individuals III-1 and III-2? its pedgree 1 and 2 not affected

    <p>Homozygous recessive</p> Signup and view all the answers

    On the pedigree of autosomal – recessive inheritance what is the genotype of the individuals III-1 and III-2? another bild with almost same as other question

    <p>Heterozygous</p> Signup and view all the answers

    Polyploidy refers to:

    <p>an individual with complete extra sets of chromosomes</p> Signup and view all the answers

    Sex-linked genes are genes that are

    <p>located on sex chromosomes</p> Signup and view all the answers

    Which genetic condition is revealed by the symptoms shown in the figure above? bild på feet and head problems

    <p>Turner syndrome</p> Signup and view all the answers

    Which genetic condition is revealed in the karyotype display shown in the figure above?

    bilden visar ingen Y chromosome

    <p>Turner syndrome</p> Signup and view all the answers

    In South Africa, variegate porphyria is found in white South Africans at a higher frequency than would be expected if the population was in Hardy-Weinberg eqiulibrium. This population originated from a small group of Dutch settlers. The most likely explanation for the high frequency of variegate in this population is:

    <p>The founder effect</p> Signup and view all the answers

    If a father is hemophiliac, hemophiliac will be his son too

    <p>False</p> Signup and view all the answers

    The pedigree represents:

    <p>An autosomal-dominant inheritance</p> Signup and view all the answers

    A woman with normal blood clotting mates with a man who also has normal blood clotting. Their first child is a boy who has hemophilia. Tests show that the child's hemophilia is X-linked and that he has normal genetic inheritance. You can predict that if the couple produces more children together, then the odds are that

    <p>half of the boys and none of the girls will have hemophilia.</p> Signup and view all the answers

    Some patients have a predisposition to developing neurodegenerative disease due to genetic mutations in the PrPC gene. If a father knows that he has the mutation, but never develops the disease, and the mother knows she is not a carrier, what is the probability that their son will develop the disease? Assume that this disease follows simple Mendelian inheritance patterns.

    <p>25%</p> Signup and view all the answers

    The change in the chromosomes depicted in the figure above represents a(n)

    <p>deletion</p> Signup and view all the answers

    The photo represents agarose gel electrophoresis patterns of ACE gene polymorphism. Which of the lanes correspond to the genotype D/D?

    SE BILDEN

    <p>5,6,9</p> Signup and view all the answers

    The chromosome on the photo below is: SE BILDEN

    <p>submetacentric</p> Signup and view all the answers

    Prenatal diagnosis techniques such as amniocentesis and chorionic villus sampling remove cells that were produced by an embryo. These cells are then used

    <p>to test for the presence of mutant alleles or chromosomal alterations.</p> Signup and view all the answers

    A genetic disorder affects three generations of males in a family, but rarely affects the females. What is one possible cause of this observation?

    <p>The mutation is recessive and occurs on the X chromosome</p> Signup and view all the answers

    The pedigree chart below is for a family, some of whose members exhibit the autosomal dominant trait, brown eye color. Brown eyed individuals are indicated by a dark square or circle. Use the chart to answer the following question: what is the genotype of individual B-4.

    SE BILDEN

    <p>Ww</p> Signup and view all the answers

    The pedigree chart below is for a family, some of whose members exhibit the autosomal dominant trait, brown eye color. Brown eyed individuals are indicated by a dark square or circle. Use the chart to answer the following question: what is the probability that individual D-3 is Ww?

    <p>1</p> Signup and view all the answers

    Study Notes

    Autosomal Recessive Inheritance

    • In autosomal recessive inheritance, an individual must inherit two copies of the recessive allele to express the trait.
    • A carrier has one copy of the recessive allele and one copy of the dominant allele. They do not express the trait but can pass it on to their offspring.

    Barr Bodies

    • A Barr body is an inactive X chromosome found in female cells.
    • Females have two X chromosomes, but one is randomly inactivated during development.
    • The inactivated X chromosome condenses into a Barr body.

    Mode of Inheritance

    • The mode of inheritance is likely X-linked dominant.
    • Affected males never produce affected children, but affected females do produce affected children of both sexes.
    • This pattern suggests the trait is carried on the X chromosome and is dominant.

    Neurofibromatosis Type 1

    • Neurofibromatosis type 1 is a common autosomal dominant disorder.
    • Heterozygous individuals have one copy of the dominant allele and express the trait.
    • If one parent is heterozygous and the other is unaffected, there is a 50% chance that their children will inherit the dominant allele and express the trait.

    Pedigree Analysis

    • The probability of individual D-3 being Ww is 100%.
    • Individual D-3 has brown eyes, which is the dominant trait.
    • They inherited one dominant allele (W) from their mother (B-4) and one recessive allele (w) from their father (C-3).

    Hemophilia A

    • Hemophilia A is an X-linked recessive disorder.
    • If a father has hemophilia A (X-linked recessive) and a mother is a carrier, their sons have a 50% chance of inheriting the disease.
    • Their daughters have a 50% chance of being carriers but will not be affected with the disease.

    Color Blindness

    • Color blindness is an X-linked recessive trait.
    • If the frequency of color-blind males is 1 in 100, the frequency of color-blind females is approximately 1 in 10,000.

    Down Syndrome

    • Down syndrome is a genetic disorder caused by an extra copy of chromosome 21.
    • This leads to moderate to severe mental retardation, sterility, and an increased risk of heart defects and other health issues.

    Fraternal Twins

    • Fraternal twins are produced when two separate eggs are fertilized by two separate sperm.
    • They are genetically distinct and have a similar relationship as any other siblings.

    Hardy-Weinberg Equilibrium

    • Hardy-Weinberg equilibrium occurs when there is no change in allele frequencies from one generation to the next.
    • The conditions required are no mutation, no gene flow, random mating, no genetic drift, and no natural selection.

    Cystic Fibrosis

    • Cystic fibrosis is an autosomal recessive disease.
    • If 25% of a population has the disease, then 50% of the population are carriers.

    Rhesus (Rh) Factor

    • If 75% of a population is Rh positive, then 25% are homozygous recessive for the Rh-negative trait.

    Identical Twins

    • Identical twins develop from a single fertilized egg that splits into two embryos.
    • They share identical DNA and are always of the same sex.

    Chromosomal Change

    • The change in the chromosome depicted in the figure represents a translocation.
    • This is where a piece of one chromosome breaks off and attaches to another.

    Nondisjunction in Meiosis I

    • Nondisjunction in meiosis I results in gametes with an extra chromosome or missing a chromosome.
    • This can lead to disorders such as Down syndrome or Turner syndrome.

    Karyotype Display

    • The karyotype display shows a missing Y chromosome, which is characteristic of Turner syndrome.
    • Turner syndrome is a genetic disorder that affects females and is characterized by short stature, heart defects, and a lack of ovaries.

    Polymerase Chain Reaction (PCR)

    • Polymerase chain reaction is a technique that amplifies DNA sequences.
    • PCR uses primers to target specific DNA sequences and allows for copies of these sequences to be made.

    Pedigree Analysis - Autosomal Recessive Inheritance

    • In autosomal recessive inheritance individuals need to inherit two recessive alleles to express the trait.
    • Individuals III-1 and III-2 are likely carriers (Aa) as they are unaffected but have a child with the trait (III-3).

    Polyploidy

    • Polyploidy refers to an organism having more than two sets of chromosomes.
    • Polyploidy can lead to changes in the organism's phenotype and is common in plants.

    Sex-Linked Genes

    • Sex-linked genes are genes that are located on the sex chromosomes (X or Y).

    Karyotype Display

    • The karyotype display shows a missing Y chromosome, which is characteristic of Turner syndrome.
    • Turner syndrome is a genetic disorder that affects females and is characterized by short stature, heart defects, and a lack of ovaries.

    Variate Porphyria

    • Variate porphyria is a genetic disorder that is more common in white South Africans than in other populations.
    • This high frequency is likely due to the founder effect, where a small group of individuals from a specific population established a new population.

    Hemophilia Inheritance

    • Hemophilia is an X-linked recessive disorder.
    • If the father has hemophilia, his sons will also have hemophilia.
    • This is because sons inherit the Y chromosome from their father and the X chromosome from their mother.

    Neurodegenerative Disease

    • If a father has the PrPC gene mutation, but does not develop the disease, and the mother is not a carrier, there is a 0% chance that their son will develop the disease.
    • This is because the son will only inherit one copy of the PrPC gene mutation from his father, which is not enough to cause the disease.

    ACE Gene Polymorphism

    • The lane corresponding to the genotype D/D would show two bands on the agarose gel, one for each allele.

    Chromosome Identification

    • The chromosome photo is a metacentric chromosome.
    • Metacentric chromosomes have the centromere located in the middle.

    Prenatal Diagnosis

    • Prenatal diagnosis techniques such as amniocentesis and chorionic villus sampling analyze the genetic material of a developing fetus.

    Observation of Family History

    • The observation of a genetic disorder affecting three generations of males, but rarely affecting females, suggests an X-linked recessive inheritance pattern.
    • Males only inherit one X chromosome, so they are more likely to express the trait if they inherit the recessive allele.

    Pedigree Analysis

    • Individual B-4 is likely heterozygous (Ww) because they have brown eyes (dominant trait) but have a child with blue eyes (recessive trait).
    • Individual B-4 must have one dominant allele (W) and one recessive allele (w).

    Pedigree Analysis

    • The probability that individual D-3 is Ww is 100%.
    • Individual D-3 has brown eyes, which is the dominant trait.
    • They inherited one dominant allele (W) from their mother (B-4) and one recessive allele (w) from their father (C-3).

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    Test your understanding of autosomal recessive inheritance with this quiz. Calculate the probability of having a son with a specific trait when one parent is affected and the other is a carrier. Dive deep into the mechanics of inheritance patterns and probabilities.

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