Podcast
Questions and Answers
What color flower was dominant in Mendel's F1 hybrids?
What color flower was dominant in Mendel's F1 hybrids?
- Blue
- Purple (correct)
- White
- Yellow
Mendel's Law of Segregation supports the blending hypothesis of heredity.
Mendel's Law of Segregation supports the blending hypothesis of heredity.
False (B)
What term did Mendel use to describe the factor for purple flowers?
What term did Mendel use to describe the factor for purple flowers?
dominant trait
Mendel observed a ratio of approximately ____ purple flowers to one white flower in the F2 generation.
Mendel observed a ratio of approximately ____ purple flowers to one white flower in the F2 generation.
Match the following traits with their corresponding terms:
Match the following traits with their corresponding terms:
How many alleles does an organism inherit for each character from its parents?
How many alleles does an organism inherit for each character from its parents?
The white flower factor was completely destroyed in the F1 generation.
The white flower factor was completely destroyed in the F1 generation.
What do we currently refer to as 'heritable factors' according to Mendel's findings?
What do we currently refer to as 'heritable factors' according to Mendel's findings?
What is the primary role of a dominant allele?
What is the primary role of a dominant allele?
Heterozygotes are true-breeding organisms.
Heterozygotes are true-breeding organisms.
What is the term for an organism with two identical alleles for a gene?
What is the term for an organism with two identical alleles for a gene?
In pea plants, the phenotypes PP and Pp will have the same ______.
In pea plants, the phenotypes PP and Pp will have the same ______.
Match the following terms to their definitions:
Match the following terms to their definitions:
What happens during gamete formation in terms of alleles?
What happens during gamete formation in terms of alleles?
In a testcross, a mystery individual is bred with a homozygous dominant individual.
In a testcross, a mystery individual is bred with a homozygous dominant individual.
What kind of phenotypic ratio is expected in the F2 generation of Mendel's crosses?
What kind of phenotypic ratio is expected in the F2 generation of Mendel's crosses?
What does Mendel's law of segregation state about factors for traits?
What does Mendel's law of segregation state about factors for traits?
A dihybrid cross involves two parents that are true-breeding for different traits.
A dihybrid cross involves two parents that are true-breeding for different traits.
What type of offspring are produced from a monohybrid cross?
What type of offspring are produced from a monohybrid cross?
Mendel's law of _________ applies to genes on different, nonhomologous chromosomes.
Mendel's law of _________ applies to genes on different, nonhomologous chromosomes.
Which outcome is expected when performing a dihybrid cross?
Which outcome is expected when performing a dihybrid cross?
Mendel’s laws reflect the rules of probability that apply to games of chance like rolling dice.
Mendel’s laws reflect the rules of probability that apply to games of chance like rolling dice.
How many factors does each gamete contain according to Mendel's law of segregation?
How many factors does each gamete contain according to Mendel's law of segregation?
What is the multiplication rule in probability?
What is the multiplication rule in probability?
The addition rule is used to calculate the probability that both events will occur simultaneously.
The addition rule is used to calculate the probability that both events will occur simultaneously.
In a heterozygous plant, what is the probability that a gamete carries the dominant allele?
In a heterozygous plant, what is the probability that a gamete carries the dominant allele?
What occurs in complete dominance?
What occurs in complete dominance?
Codominance results in a phenotype that is an intermediate between the two parental varieties.
Codominance results in a phenotype that is an intermediate between the two parental varieties.
In an autosomal recessive inheritance pattern, both parents must pass an altered gene for their child to inherit the ______.
In an autosomal recessive inheritance pattern, both parents must pass an altered gene for their child to inherit the ______.
Match the following concepts with their definitions:
Match the following concepts with their definitions:
What is the term for alleles that cause multiple symptoms in hereditary diseases?
What is the term for alleles that cause multiple symptoms in hereditary diseases?
The trait of polydactyly is caused by a __________ allele.
The trait of polydactyly is caused by a __________ allele.
What is required for a child to inherit an autosomal recessive trait?
What is required for a child to inherit an autosomal recessive trait?
Mendel's principles of segregation and independent assortment apply to complex patterns of inheritance.
Mendel's principles of segregation and independent assortment apply to complex patterns of inheritance.
How many alleles determine the ABO blood group phenotypes in humans?
How many alleles determine the ABO blood group phenotypes in humans?
What is the main reason why parents with an autosomal recessive trait may not be aware they carry it?
What is the main reason why parents with an autosomal recessive trait may not be aware they carry it?
Match the type of genetic interaction with its definition:
Match the type of genetic interaction with its definition:
Dominant alleles are always more common than recessive alleles in a population.
Dominant alleles are always more common than recessive alleles in a population.
What happens in incomplete dominance?
What happens in incomplete dominance?
What advantage do heterozygotes with sickle-cell trait have in regions where malaria is prevalent?
What advantage do heterozygotes with sickle-cell trait have in regions where malaria is prevalent?
Methemoglobinemia is commonly referred to as 'blue baby syndrome'.
Methemoglobinemia is commonly referred to as 'blue baby syndrome'.
What condition causes an amino acid called phenylalanine to build up in the body?
What condition causes an amino acid called phenylalanine to build up in the body?
In autosomal dominant inheritance, only one _____ needs to have an altered gene to pass on the trait to their children.
In autosomal dominant inheritance, only one _____ needs to have an altered gene to pass on the trait to their children.
Match the following disorders with their characteristics:
Match the following disorders with their characteristics:
Which of the following statements about autosomal dominant traits is correct?
Which of the following statements about autosomal dominant traits is correct?
All human disorders caused by dominant alleles are lethal.
All human disorders caused by dominant alleles are lethal.
What lifestyle adaptation is required for individuals with Phenylketonuria?
What lifestyle adaptation is required for individuals with Phenylketonuria?
Flashcards
Law of Segregation
Law of Segregation
During gamete formation, the two alleles for each gene separate, with each gamete receiving only one allele.
Alleles
Alleles
Alternative versions of a gene that produce variations in inherited traits.
Dominant Trait
Dominant Trait
The trait that is expressed when different alleles are present.
Recessive Trait
Recessive Trait
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Gene
Gene
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F1 generation
F1 generation
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F2 generation
F2 generation
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Blending hypothesis
Blending hypothesis
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Dominant Allele
Dominant Allele
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Recessive Allele
Recessive Allele
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Homozygote
Homozygote
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Heterozygote
Heterozygote
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Phenotype
Phenotype
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Genotype
Genotype
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Testcross
Testcross
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Monohybrid Cross
Monohybrid Cross
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Dihybrid Cross
Dihybrid Cross
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Law of Independent Assortment
Law of Independent Assortment
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Probability in Inheritance
Probability in Inheritance
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Monohybrid
Monohybrid
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Dihybrid
Dihybrid
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Multiplication Rule
Multiplication Rule
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Addition Rule
Addition Rule
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Segregation (of alleles)
Segregation (of alleles)
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Autosomal Recessive Inheritance
Autosomal Recessive Inheritance
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Independent Events
Independent Events
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Multicharacter Cross
Multicharacter Cross
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Complex Inheritance Patterns
Complex Inheritance Patterns
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Complete Dominance
Complete Dominance
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Incomplete Dominance
Incomplete Dominance
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Codominance
Codominance
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Pleiotropy
Pleiotropy
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Epistasis
Epistasis
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Polygenic Inheritance
Polygenic Inheritance
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Multiple Alleles
Multiple Alleles
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What causes wrinkled peas?
What causes wrinkled peas?
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Sickle-cell trait
Sickle-cell trait
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Heterozygote Advantage
Heterozygote Advantage
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What causes Methemoglobinemia?
What causes Methemoglobinemia?
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What is Phenylketonuria (PKU)?
What is Phenylketonuria (PKU)?
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Autosomal Dominant Inheritance
Autosomal Dominant Inheritance
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Dominantly Inherited Disorders
Dominantly Inherited Disorders
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What is Achondroplasia?
What is Achondroplasia?
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Dominant Alleles & Lethal Diseases
Dominant Alleles & Lethal Diseases
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Study Notes
Mendelian Patterns of Inheritance
- Gregor Mendel's experiments with pea plants established the fundamental principles of heredity.
- The "blending" hypothesis of inheritance proposed that offspring traits were a mix of parental traits.
- Mendel's experiments refuted this, revealing a "particulate" nature of inheritance, with traits determined by discrete units (now known as genes).
Mendel's Experimental Approach
- Mendel chose observable traits with distinct forms (e.g., flower colour).
- He used true-breeding varieties for accurate results.
- He controlled matings to avoid chance variations.
- He tracked generations.
- Mendel's quantitative approach allowed him to deduce principles of inheritance.
- Characters (heritable traits) vary among individuals.
- Traits (variants of a character) include colours or other observable differences.
- Peas were readily available to Mendel in many varieties.
- Specific advantages of using peas in genetic studies include short generation time, relatively large numbers of offspring, and ease of controlled mating.
- Mendel meticulously tracked the inheritance patterns of seven pea plant traits.
Mendel's Laws
- The Law of Segregation: During gamete formation, the two alleles for a trait separate, with each gamete receiving only one allele.
- This explains the 3:1 ratio of traits observed in the F2 generation of a monohybrid cross.
- The Law of Independent Assortment: Different alleles independently segregate during gamete formation.
- This principle accounts for the inheritance of multiple traits.
- The process of hybridization involves mating two contrasting, true-breeding varieties.
Mendel's Model – Concepts
- First: Alternative versions of genes (Alleles) account for variations in inherited characters.
- Second: For each character, an organism inherits two alleles, one from each parent.
- Third: If the two alleles at a locus differ, the dominant allele determines the organism's appearance, while the recessive allele has no noticeable effect.
- Fourth: The law of segregation; the two alleles of a heritable trait separate (segregate) during gamete formation and end up in different gametes.
Punnett Squares
- Predicting the possible outcomes of crosses.
- A diagram that depicts all possible genotypes of offspring.
Dominant vs. Recessive Alleles
- Dominant alleles are expressed in heterozygous individuals; recessive alleles are only expressed if an individual is homozygous recessive.
Homozygous vs. Heterozygous
- Homozygous individuals have two identical alleles for a gene, while heterozygous individuals have two different alleles.
Genotype vs. Phenotype
- Genotype refers to the alleles an organism possesses for a particular trait.
- Phenotype refers to the observable characteristics resulting from those alleles.
Testcross
- Used to determine the genotype of an individual that displays the dominant phenotype by crossing the unknown genotype to a homozygous recessive one.
- The results reveal whether the unknown parent is homozygous dominant or heterozygous.
Extending Mendelian Genetics (Beyond Single Genes)
- Multiple genes may contribute to a trait.
- Epistasis: A gene at one locus alters the phenotypic expression of a gene at a second locus.
- Polygenic inheritance: Multiple genes independently affect a single phenotype.
- Multifactorial traits: Genes influenced by environmental factors.
Degrees of Dominance
- Complete dominance: Phenotype of the heterozygote is identical to the homozygous dominant one.
- Incomplete dominance: Phenotype of the heterozygote is a blend of the two parental phenotypes (e.g., pink flowers from a cross between red and white).
- Codominance: Two dominant alleles affect the phenotype in distinct ways—both traits are expressed in the heterozygote (e.g., spotted or striped animals).
Multiple Alleles
- Most genes have more than two alleles for a trait in the population.
- The ABO blood groups in humans demonstrate this—controlled by three alleles.
- Alleles can be expressed in various ways—co-dominantly or even as a hierarchy where one or more alleles could be recessive to multiple others.
Pleiotropy
- Many genes can have multiple phenotypic effects.
- This can be particularly seen in hereditary diseases like cystic fibrosis and sickle-cell disease.
X-Linked Inheritance
- Traits controlled by genes located on the X chromosome display unique inheritance patterns, often affecting males more frequently.
- Different behaviours—completely recessive, incompletely dominant, or codominant—are possible across the allelic variations.
Pedigree Analysis
- Geneticists use pedigrees to analyse inherited traits across multiple generations in families.
- This allows for determining patterns of inheritance and the likelihood of offspring inheriting a trait.
Nature vs. Nurture (Environmental Influences)
- Many traits depend both on genes and the environment.
- These factors together influence the observable traits—phenotype.
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Description
Explore the groundbreaking work of Gregor Mendel and his experiments with pea plants that established the essential principles of heredity. Learn about the differences between blending and particulate inheritance, and understand how Mendel's careful methods laid the foundation for modern genetics. This quiz covers Mendel's experimental approach and the traits he studied.
