Non-Mendelian Genetics Overview
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Questions and Answers

What term describes the variation in the degree of expression of a particular gene due to environmental factors?

  • Expressivity (correct)
  • Pleiotropy
  • Penetrance
  • Epistasis

Which of the following is an example of pleiotropy?

  • A mutation leading to a variety of traits such as mental retardation and skin patches in Phenylketonuria (correct)
  • A single trait dictated by multiple genes
  • A gene causing only a change in fur color
  • A gene that influences only plant height

What ratio corresponds to complementary gene interaction?

  • 9:3:4
  • 12:3:1
  • 15:1
  • 9:7 (correct)

Which term best describes when one gene masks the effect of another gene?

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

In the context of expressivity, what does the vestigial wing in Drosophila exemplify?

<p>Variation in gene expression leading to different wing sizes (D)</p> Signup and view all the answers

Which of the following describes a situation in which both alleles are expressed equally in the phenotype?

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

Which term refers to the proportion of individuals expressing a certain trait for a specific genotype?

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

What is the result of incomplete dominance in phenotype expression?

<p>Traits are blended together (A)</p> Signup and view all the answers

Which of the following types of traits are expressed differently in males and females?

<p>Sex-limited traits (A)</p> Signup and view all the answers

What characterizes lethal genotypes?

<p>They can be dominant or recessive (D)</p> Signup and view all the answers

Which example illustrates incomplete penetrance?

<p>Some individuals with a genotype do not show the trait (C)</p> Signup and view all the answers

What is the role of pleiotropy in genetics?

<p>One gene affects multiple traits (C)</p> Signup and view all the answers

What differentiates sex-influenced traits from other types of traits?

<p>They have a varied expression in males and females (C)</p> Signup and view all the answers

Flashcards

Multiple alleles

A gene with more than two possible alleles, leading to various trait variations.

Lethal genotypes

Genotype combinations that cause death before or shortly after birth.

Incomplete dominance

Blending of traits from both alleles, resulting in a new phenotype.

Co-dominance

Both alleles are fully expressed, resulting in both features appearing.

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Sex-linked traits

Traits determined by genes located on sex chromosomes (X or Y).

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Sex-limited traits

Traits present in both sexes but expressed only in one due to hormonal differences.

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Penetrance

The likelihood that a genotype will express a specific phenotype.

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Expressivity

The degree or intensity of a trait expressed in individuals with the same genotype.

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Pleiotropy

When a single gene affects multiple seemingly unrelated traits.

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Phenylketonuria

A genetic disorder caused by the accumulation of phenylalanine in the blood due to a defective gene. It leads to a range of symptoms like mental retardation, skin abnormalities, and more.

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What is the 9:7 ratio in Mendelian genetics?

The 9:7 ratio is observed in complementary gene interaction. It results when two dominant alleles from different genes are required together for a specific phenotype to be expressed.

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Study Notes

Non-Mendelian Genetics

  • Non-Mendelian genetics study traits that do not follow Mendel's laws.
  • Mendel's proposals do not apply in these cases and the expected phenotype ratio will differ.

Inheritance Patterns

  • Inheritance patterns are not always distributed according to Mendel's rules.
  • Some characteristic inheritance patterns include:
    • Multiple alleles
    • Lethal genotypes
    • Incomplete dominance
    • Co-dominance
    • Penetrance
    • Expressivity
    • Pleiotropy
    • Epistasis

Multiple Alleles

  • Multiple alleles are when more than two alleles code for a single characteristic.
  • A key example is blood type.

Lethal Genotypes

  • Dominant lethal genes and recessive lethal genes can be detected in the population.

Incomplete Dominance

  • Incomplete dominance involves the blending of traits from alleles.
  • The resulting phenotype is a blend of the parental traits.

Co-dominance

  • Co-dominance is when both alleles are expressed equally in the phenotype.

Sex-linked Traits

  • Sex-linked traits are located on sex chromosomes and are inherited accordingly.

X-Linked Recessive Traits

  • Inheritance patterns of X-linked recessive traits are shown through pedigrees.

Sex-limited Traits

  • These are genes present in both sexes but expressed in only one, 'turned off' in the other sex.
  • These traits are found on autosomal chromosomes.

Sex-influenced Traits

  • These traits are expressed differently in males and females.
  • The phenotypic expression is influenced by hormones.

Pattern Baldness

  • Pattern baldness in humans is influenced by the hormone testosterone.

Penetrance

  • Penetrance is the percentage of individuals expressing a character.
  • Can be complete (100%) or incomplete.

Expressivity

  • Expressivity is the degree of expression of a particular gene in individuals.
  • Its variation depends on factors like the environment.

Pleiotropy

  • Pleiotropy is when one gene influences multiple, seemingly unrelated phenotypic traits.

Phenylketonuria (PKU)

  • The genes for PKU cause the accumulation of phenylalanine in the blood.
  • PKU results in a range of phenotypic traits, including mental retardation.

Modified Dihybrid Cross Ratios

  • Gene interactions such as complementary, supplementary, epistasis, and duplicate interactions have different phenotypic ratios.

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Non-Mendelian Genetics PDF

Description

Explore the complexities of non-Mendelian genetics, which examines inheritance patterns that deviate from Mendel's classic laws. The quiz covers multiple alleles, lethal genotypes, incomplete dominance, and co-dominance among other inheritance patterns. Test your understanding of these advanced concepts in genetics.

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