Non-Mendelian Inheritance Quiz
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Questions and Answers

Which of the following is NOT a rule of Mendelian inheritance?

  • The expression of genes in offspring directly influences their traits.
  • Genes are expressed in a dominant/recessive pattern. (correct)
  • The genes are passed unaltered from generation to generation.
  • Genes obey Mendel's law of segregation.

    • What is the term for the inheritance pattern that breaks the Mendelian rule of genes being passed unaltered from generation to generation?

  • Dosage compensation
  • Maternal effect
  • Epigenetics
  • Mutation (correct)

    • What is the term for the inheritance pattern that describes the influence of the mother's genotype on the offspring's phenotype, even if the offspring does not inherit the mother's specific alleles?

  • Extranuclear inheritance
  • Imprinting
  • Maternal effect (correct)
  • Dosage compensation

    • What is the term for the inheritance pattern that describes how different alleles are expressed depending on which parent they came from?

    <p>Imprinting (D)</p> Signup and view all the answers

    Which of the following is NOT a type of non-Mendelian inheritance?

    <p>Mendel's Law of Segregation (A)</p> Signup and view all the answers

    What is the Barr body?

    <p>A highly condensed X chromosome (B)</p> Signup and view all the answers

    What is the Lyon hypothesis?

    <p>The theory that dosage compensation in mammals occurs by the inactivation of a single X chromosome in females (B)</p> Signup and view all the answers

    What is the mechanism of dosage compensation in mammals?

    <p>The inactivation of a single X chromosome in female mammals (D)</p> Signup and view all the answers

    What is the relationship between the Lyon hypothesis and the Barr body?

    <p>The Barr body is the result of the Lyon hypothesis (A)</p> Signup and view all the answers

    Which of the following is NOT a key process involved in dosage compensation in mammals?

    <p>DNA replication (B)</p> Signup and view all the answers

    What is the term used to describe a cell that contains both normal and mutated chloroplasts?

    <p>Heteroplasmy (B)</p> Signup and view all the answers

    In the inheritance of organelles, which gamete typically contributes the majority of the cytoplasm to the zygote in heterogamous species?

    <p>Female gamete (D)</p> Signup and view all the answers

    Which type of chloroplasts result in a white phenotype in the leaves?

    <p>Mutated chloroplasts (D)</p> Signup and view all the answers

    What is the primary reason for maternal inheritance of organelles like chloroplasts?

    <p>The mother's gamete contributes most of the cytoplasm (A)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of paternal leakage?

    <p>It occurs in all species (D)</p> Signup and view all the answers

    What is the phenotypic consequence of heteroplasmy in terms of chloroplasts?

    <p>A variegated phenotype with patches of different colors (C)</p> Signup and view all the answers

    How many paternal mitochondria are typically inherited for every 100,000 maternal mitochondria per generation in mice?

    <p>1 to 4 (D)</p> Signup and view all the answers

    What is the term used to describe the inheritance pattern where the maternal parent is the primary source of organelles?

    <p>Maternal inheritance (C)</p> Signup and view all the answers

    In which of the following organisms is mitochondrial inheritance usually maternal?

    <p>Mammals (C)</p> Signup and view all the answers

    Which of the following organisms exhibits biparental inheritance of mitochondria?

    <p>Angiosperms (D)</p> Signup and view all the answers

    In Chlamydomonas, which mating type transmits chloroplasts to the offspring?

    <p>mt+ (D)</p> Signup and view all the answers

    Which of the following is NOT a factor contributing to mitochondrial DNA damage?

    <p>Exposure to ultraviolet radiation (A)</p> Signup and view all the answers

    Mitochondrial diseases are typically chronic degenerative disorders affecting cells requiring high levels of which molecule?

    <p>ATP (D)</p> Signup and view all the answers

    What term describes the presence of a mixture of normal and mutated mitochondria within a cell?

    <p>Heteroplasmy (D)</p> Signup and view all the answers

    Which of the following mitochondrial genes is NOT associated with Leber hereditary optic neuropathy?

    <p>ATPase6 (C)</p> Signup and view all the answers

    Which of the following statements about mitochondrial inheritance is TRUE?

    <p>Mitochondrial inheritance patterns can vary depending on the organism and species. (A)</p> Signup and view all the answers

    Which of the following statements about mutations in mitochondrial DNA is FALSE?

    <p>Mitochondrial mutations are always inherited from the mother. (D)</p> Signup and view all the answers

    According to the endosymbiosis theory, which type of bacteria is believed to be the ancestor of mitochondria?

    <p>Gram-negative, nonsulfur purple bacteria (A)</p> Signup and view all the answers

    If a female water snail with a genotype of dd mates with a male water snail with a genotype of DD, what will be the phenotype of their offspring?

    <p>Left-handed (B)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of maternal effect?

    <p>The phenotype of the offspring is determined by the genotype of the offspring itself. (B)</p> Signup and view all the answers

    What is the main reason why the phenotype of a water snail offspring is determined by the mother's genotype?

    <p>The mother provides gene products that influence the development of the offspring. (B)</p> Signup and view all the answers

    Which of the following examples best illustrates the concept of maternal effect?

    <p>A female bird lays eggs that are different colors depending on the availability of food during egg formation. (C)</p> Signup and view all the answers

    How does maternal effect break the first rule of Mendelian inheritance?

    <p>It shows that the genotype of the offspring does not always govern its phenotype. (D)</p> Signup and view all the answers

    What is the significance of the study performed by Boycott, Diver, and Eastwood in the 1920s regarding water snails?

    <p>It established that the phenotype of offspring can be influenced by the mother’s genotype, regardless of the offspring’s own genotype. (A)</p> Signup and view all the answers

    Which of the following is TRUE about the genes involved in maternal effect?

    <p>The genes are located in the nucleus. (D)</p> Signup and view all the answers

    What is the primary reason why maternal effect is considered a non-Mendelian pattern of inheritance?

    <p>It demonstrates that the phenotype is not always determined by the genotype. (A)</p> Signup and view all the answers

    What is the term used for the phenomenon where only one allele of a gene is expressed, regardless of whether it's inherited from the mother or father?

    <p>Monoallelic expression (C)</p> Signup and view all the answers

    Flashcards

    Mendelian Inheritance

    A type of genetic inheritance following Mendel's four rules.

    Maternal Effect

    Phenotypic traits influenced by the mother's genotype regardless of the offspring's genotype.

    Epigenetics

    Study of changes in gene expression caused by mechanisms other than the DNA sequence.

    Dosage Compensation

    Process that balances the expression of genes between sexes, especially X-linked genes.

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    Gene Linkage

    The tendency of genes located close to each other on a chromosome to be inherited together.

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    Barr Body

    A highly condensed X chromosome found in female somatic cells.

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    Lyon Hypothesis

    Proposes X-chromosome inactivation as a method of dosage compensation in females.

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    X-Chromosome Inactivation

    The process where one X chromosome in females is randomly inactivated during development.

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    Variegated Coat Color in Mice

    Phenomenon seen in certain mice due to random X-inactivation leading to different fur colors.

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    Independent Assortment

    Mendel’s principle that describes how genes segregate independently during gamete formation.

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    Epigenetic Inheritance

    Changes in gene expression due to modifications, like methylation, without altering the DNA sequence.

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    Extranuclear Inheritance

    Inheritance of genes located outside the nucleus, often found in organelles like mitochondria.

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    Linkage

    When genes are close together on the same chromosome and do not assort independently.

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    Phenotype Determination

    In maternal effect, the mother's genotype solely determines the offspring's phenotype.

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    Dextral vs. Sinistral

    Dextral (right-handed) is dominant over sinistral (left-handed) in certain organisms like snails.

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    Water Snail Example

    In the water snail Limnaea peregra, maternal genotype determines offspring shell direction.

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    Pseudoautosomal Genes

    Genes on the inactivated X chromosome that escape inactivation due to presence on Y chromosome.

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    Genomic Imprinting

    DNA marking process where only one allele is expressed depending on parent of origin.

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    Monoallelic Expression

    Expression of only one of the two alleles in a gene, either maternal or paternal.

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    Igf2 Gene

    Gene encoding insulin-like growth factor 2, important for normal growth.

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    Imprinted Allele

    An allele that is marked and not expressed due to genomic imprinting.

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    Loss-of-function Allele

    An allele that produces no functional protein, affecting phenotype.

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    Stages of Imprinting

    Processes involving establishing, maintaining, and erasing the genetic imprint.

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    Reciprocal Cross

    Breeding experiment where phenotypes differ but genotypes are identical.

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    Maternal Inheritance

    Transmission of organelles exclusively from the mother through the egg's cytoplasm.

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    Chloroplasts and Phenotype

    The type of chloroplasts in leaf cells determines the leaf phenotype.

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    Green Phenotype

    Wild-type phenotype associated with normal chloroplasts that produce green pigment.

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    White Phenotype

    Mutant phenotype lacking green pigments due to chloroplast mutation.

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    Variegated Phenotype

    Condition where leaf cells contain a mix of different types of chloroplasts.

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    Heteroplasmy

    The presence of more than one type of organelle genome within a cell.

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    Heterogamous Species

    Species producing two types of gametes, typically inherited from the mother.

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    Paternal Leakage

    Occasional transmission of paternal mitochondria through sperm, rare in maternal inheritance.

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    Biparental inheritance

    Inheritance of mitochondrial DNA from both parents, though rare.

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    Human mtDNA

    Mitochondrial DNA passed from mother to child via egg cytoplasm.

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    Mitochondrial diseases

    Genetic disorders caused by mutations in mitochondrial DNA.

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    Leber hereditary optic neuropathy

    Condition caused by mitochondrial mutations affecting vision.

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    Neurogenic muscle weakness

    A mitochondrial disease due to mutations in the ATPase6 gene.

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    Endosymbiosis theory

    Theory explaining the origin of mitochondria and chloroplasts from bacteria.

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    Chlamydomonas inheritance

    Mitochondria inherited from the mt- mating type, chloroplasts from mt+.

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    Chloroplast origin

    Chloroplasts originated from ancient cyanobacteria through endosymbiosis.

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    Study Notes

    Non-Mendelian Inheritance

    • The four rules of Mendelian inheritance are broken by the following patterns: maternal effect, epigenetic inheritance, extranuclear inheritance, and linkage
    • Maternal effect: the genotype of the mother directly affects the phenotype of her offspring, not the father's or offspring's. It's due to the accumulation of gene products in the mother's eggs that are passed to the offspring
    • Example: water snail, Limnaea peregra, shell coiling direction (dextral or sinistral). Dextral is dominant
    • Epigenetic inheritance: modifications occur to a nuclear gene or chromosome altering gene expression, but not changing the DNA sequence. It is not permanent and reversible
    • Example: dosage compensation and genomic imprinting
    • Dosage compensation offsets differences in the number of active sex chromosomes in different species (mammals vs. birds). It occurs during oogenesis, spermatogenesis, or early embryonic development
    • Genomic imprinting: a DNA segment is marked, and the effect is maintained throughout the organism's life. Only one allele is expressed, not both (monoallelic expression). This depends on how the genes are marked (maternally or paternally)
    • Extranuclear inheritance: genes in organelles other than the nucleus are involved
    • Example: mitochondria and chloroplasts. Mitochondria and chloroplasts have their own genetic material (nucleoid)
    • Mitochondria have a single circular chromosome containing double-stranded DNA
    • Chloroplasts are typically 10 times larger than mitochondrial genomes
    • Chloroplasts and mitochondria have their own genetic material, and proteins encoded in the nucleus are required

    Linkage and Mapping in Eukaryotes

    • In eukaryotic species, chromosomes typically contain multiple genes. Genes located on the same chromosome and physically linked undergo synteny.
    • Linkage: Genes close together on a chromosome tend to be transmitted as a unit and this affects inheritance patterns
    • Linkage groups are chromosomes that contain groups of genes linked together
    • The number of linkage groups equals the number of chromosomes in a species. In humans, there are 22 autosomal linkage groups, along with an X and Y chromosome linkage group.
    • Crossing over during meiosis can alter linkage
    • Crossing over occurs during prophase I of meiosis, where replicated sister chromatid homologues associate as bivalents. Non-sister chromatids exchange DNA segments
    • Crossing over may result in recombinant genotypes (a combination of alleles NOT found in the original chromosomes)
    • If crossing over does not occur, the original combination of alleles is maintained in gametes

    Mitochondrial Diseases

    • Mitochondria DNA (mtDNA) is transmitted from the mother to offspring via the cytoplasm of the egg.
    • Mitochondrial mutations can occur in somatic cells and accumulate with age
    • Mitochondria are vulnerable to DNA damage due to high oxygen consumption, leading to free radicals; mtDNA has limited repair abilities
    • Heteroplasmy (a mixed population of mitochondria within a cell) is an important factor in mitochondrial disease, because disease may only occur when the ratio of mutant to normal mitochondria exceeds a threshold value.
    • Species with paternal leakage: the paternal parent occasionally provides mitochondria through the sperm.

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    Related Documents

    Chapter 5 & 6 Non-Mendelian Inheritance PDF

    Description

    Test your knowledge on non-Mendelian inheritance patterns and concepts. This quiz covers topics such as the Lyon hypothesis, Barr bodies, and dosage compensation in mammals. Challenge yourself with questions regarding inheritance mechanisms that deviate from Mendelian rules.

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