Genetics and Inheritance Patterns Medium
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Questions and Answers

What is the term for the pattern where a dominant allele is present but its effect is not visible?

  • Dominance
  • Penetrance (correct)
  • Incomplete dominance
  • Overdominance

    • In a case of incomplete dominance, what is the phenotype of the heterozygous offspring?

  • The same as the dominant homozygote
  • Intermediate between the two homozygotes (correct)
  • More extreme than both homozygotes
  • The same as the recessive homozygote

    • What is the term for the situation where the heterozygote has a more beneficial trait than either homozygote?

  • Incomplete dominance
  • Overdominance (correct)
  • Penetrance
  • Dominance

    • What is the reason for penetrance, according to the molecular perspective?

    <p>The protein encoded by the gene is counteracted by other genes</p> Signup and view all the answers

    What is the term for the pattern where the heterozygote expresses both alleles simultaneously without forming an intermediate phenotype?

    <p>Co-dominance</p> Signup and view all the answers

    Why may heterozygotes have increased resistance to infection by microorganisms?

    <p>All of the above</p> Signup and view all the answers

    What is the result of a cross between homozygous red-flowered and homozygous white-flowered parents, in terms of flower color?

    <p>Pink flowers</p> Signup and view all the answers

    In dominant and recessive alleles, what is the main difference between the dominant and recessive alleles?

    <p>The dominant allele is always expressed, while the recessive allele is not</p> Signup and view all the answers

    What is a characteristic of simple Mendelian inheritance?

    <p>A single gene with two different alleles</p> Signup and view all the answers

    What is the main goal of examining different patterns of Mendelian inheritance?

    <p>To understand the relationship between the molecular expression of a gene and the trait itself</p> Signup and view all the answers

    What is the term applied to the inheritance of alleles that obey Mendel's laws and follow a strict dominant/recessive relationship?

    <p>Mendelian inheritance</p> Signup and view all the answers

    What can occur when a single gene has three or more alleles?

    <p>The relationship between the alleles becomes more complex</p> Signup and view all the answers

    What is the result of a single copy of a dominant allele in a heterozygote?

    <p>50% of the protein is produced</p> Signup and view all the answers

    What is an example of a complex inheritance pattern?

    <p>A single gene with three alleles</p> Signup and view all the answers

    What is the relationship between genetic polymorphism and Mendelian inheritance?

    <p>Genetic polymorphism is an example of complex Mendelian inheritance</p> Signup and view all the answers

    What is the result of a mutation in a gene?

    <p>All of the above</p> Signup and view all the answers

    What is the blood type of an individual carrying the A and B alleles?

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

    In X-linked inheritance, what percentage of the protein produced by a single copy of the dominant allele is sufficient to produce the dominant trait in a heterozygous female?

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

    What type of inheritance pattern involves the effect of sex on the phenotype of the individual?

    <p>Sex-influenced inheritance</p> Signup and view all the answers

    Which type of inheritance pattern involves traits that occur in only one of the two sexes?

    <p>Sex-limited inheritance</p> Signup and view all the answers

    What is the main difference between sex-influenced and sex-limited inheritance patterns?

    <p>Sex-influenced inheritance refers to the effect of sex on the phenotype, while sex-limited inheritance refers to traits that occur in only one sex</p> Signup and view all the answers

    In X-linked inheritance, what is the expression of the copy of the gene that males carry?

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

    What is an example of codominance?

    <p>Blood type A and B</p> Signup and view all the answers

    What regulates the molecular expression of genes in sex-influenced and sex-limited inheritance patterns?

    <p>Sex hormones</p> Signup and view all the answers

    Study Notes

    Inheritance Patterns

    • Incomplete Penetrance: A dominant allele is present, but its effects are not seen due to environmental influences or counteracting proteins from other genes.

    Incomplete Dominance

    • A heterozygote has a phenotype that is intermediate between the two corresponding homozygotes, e.g., a cross between red-flowered and white-flowered parents produces pink-flowered offspring.

    Overdominance

    • A heterozygote has a trait that is more beneficial than either homozygote.
    • Three ways heterozygotes gain benefits:
      • Increased resistance to infection by microorganisms
      • Producing more forms of protein dimers with enhanced function
      • Producing proteins that function under a wider range of conditions

    Extensions of Mendelian Inheritance

    • Mendelian inheritance describes patterns that obey two laws: the Law of Segregation and the Law of Independent Assortment.
    • Simple Mendelian inheritance involves a single gene with two different alleles that display a simple dominant/recessive relationship.

    Codominance

    • The codominant alleles encode proteins that function slightly differently from each other, and the function of each protein in the heterozygote affects the phenotype uniquely.
    • Example: blood typing, where an individual carrying the A and B alleles will have an AB blood type.

    X-linked Inheritance

    • Inheritance of genes located on the X chromosome.
    • In mammals and fruit flies, males have one copy of X-linked genes, whereas females have two copies.
    • If a pair of X-linked alleles shows a simple dominant/recessive relationship, 50% of the protein produced by a single copy of the dominant allele in a heterozygous female is sufficient to produce the dominant trait.

    Sex-influenced Inheritance

    • The effect of sex on the phenotype of an individual.
    • Some alleles are recessive in one sex and dominant in the opposite sex.
    • Sex hormones may regulate the molecular expression of genes, influencing the phenotypic effects of alleles.

    Sex-limited Inheritance

    • Traits that occur in only one of the two sexes.
    • Example: breast development in mammals.
    • Sex hormones that are primarily produced in only one sex are essential to produce a particular phenotype.

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