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One reason Mendel probably chose to work with peas is because they have many varieties. Which of the following are "varieties" of peas?
One reason Mendel probably chose to work with peas is because they have many varieties. Which of the following are "varieties" of peas?
What is the term for a specific characteristic that can vary in an organism, like flower color?
What is the term for a specific characteristic that can vary in an organism, like flower color?
Character
What is the term for a specific variation of a character, like purple flowers?
What is the term for a specific variation of a character, like purple flowers?
Trait
Each pea flower has both ______-producing organs and an egg-bearing organ.
Each pea flower has both ______-producing organs and an egg-bearing organ.
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What is the term for the mating of two true-breeding varieties called?
What is the term for the mating of two true-breeding varieties called?
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Which of the following are fundamental principles of heredity?
Which of the following are fundamental principles of heredity?
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The "heritable factor" for white flowers is destroyed in the F1 generation.
The "heritable factor" for white flowers is destroyed in the F1 generation.
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The "heritable factor" for white flowers is masked by the presence of the factor for purple flowers.
The "heritable factor" for white flowers is masked by the presence of the factor for purple flowers.
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What is a gene according to modern terminology?
What is a gene according to modern terminology?
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A gene is the same as an allele.
A gene is the same as an allele.
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Alternative versions of genes account for variations in inherited characters. These alternative versions of genes are called ______.
Alternative versions of genes account for variations in inherited characters. These alternative versions of genes are called ______.
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In a diploid cell, a genetic locus is represented twice.
In a diploid cell, a genetic locus is represented twice.
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An organism inherits two versions of a gene, both from the same parent.
An organism inherits two versions of a gene, both from the same parent.
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If two alleles at a locus differ, then the dominant allele determines the organism's appearance.
If two alleles at a locus differ, then the dominant allele determines the organism's appearance.
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The two alleles for a heritable character segregate during gamete formation
The two alleles for a heritable character segregate during gamete formation
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The two alleles for heritable character separate and are not present in the same gamete.
The two alleles for heritable character separate and are not present in the same gamete.
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The terms "gene" and "heritable factor" refer to the same thing.
The terms "gene" and "heritable factor" refer to the same thing.
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What does a Punnett square predict?
What does a Punnett square predict?
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A homozygous recessive genotype is represented with two lowercase letters.
A homozygous recessive genotype is represented with two lowercase letters.
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A heterozygous genotype is represented with two different case letters.
A heterozygous genotype is represented with two different case letters.
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The Law of Segregation originated from experiments following only a single character.
The Law of Segregation originated from experiments following only a single character.
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The F1 progeny produced in crosses of true-breeding parents are dihybrids.
The F1 progeny produced in crosses of true-breeding parents are dihybrids.
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The second law of inheritance is based on experiments with two characters at the same time.
The second law of inheritance is based on experiments with two characters at the same time.
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The testcross hypothesis suggests that two pairs of alleles segregate independently of each other.
The testcross hypothesis suggests that two pairs of alleles segregate independently of each other.
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The law of independent assortment states that each pair of alleles segregates independently during gamete formation.
The law of independent assortment states that each pair of alleles segregates independently during gamete formation.
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Study Notes
Mendel and the Gene Idea
- Mendel used pea plants to study inheritance
- Pea plants have many varieties, for example, purple flowers and white flowers
- Flower color is a character; purple or white is a trait
- Pea plants typically self-fertilize
- Short generation time and many offspring facilitated breeding experiments
- True-breeding plants produce only offspring with the same trait as the parent
- Hybridization is crossing two true-breeding varieties
- Mendel's experiments led to two fundamental laws of inheritance
The Law of Segregation
- Heritable factors (genes) for a trait are not destroyed or blended; they remain distinct
- Recessive traits are masked by dominant traits, but not lost
- When crossing hybrid plants, a 3:1 ratio of offspring with different traits emerged in the F2 generation (second filial generation)
- The two alleles for a character segregate during gamete formation
- Each gamete receives one allele for each character trait
The Law of Independent Assortment
- Two or more genes assort independently of one another during gamete formation
- Different traits do not affect each other in inherited traits, they are independent
- The inheritance of one trait does not influence the inheritance of another
- This observation resulted in the 9:3:3:1 phenotypic ratio
Degrees of Dominance
- Complete dominance: Heterozygotes look identical to homozygous dominant individuals.
- Incomplete dominance: Heterozygotes display a phenotype that is an intermediate between homozygous phenotypes ex) Pink flowers from a red and white flower cross
- Codominance: Heterozygotes display both homozygous expressions simultaneously
- ex) A person with blood type AB
Multiple Alleles
- Multiple alleles for some genes exist within a population
- Multiple alleles for a gene are alleles encoding a variation of the same gene
- ABO blood groups is an example of a multiple allele system in humans
Epistasis
- Epistasis occurs when one gene alters the expression of another gene
- Ex: Coat color in Labrador retrievers is controlled by more than one gene. In these breeds, one gene determines if pigment will be made at all.
- If no pigment is made, the coat color will be yellow, regardless of which color gene is present.
Nature and Nurture
- Environmental factors can influence the phenotype (observable characteristic) of an organism
- Phenotype is affected by both genetics and the environment.
- Ex: Human height affected by diet
- Ex: Skin color affected by sun exposure.
Polygenic Inheritance
- Multiple genes may affect a single characteristic
- Ex: Human skin color depends on several genes, each contributing a small amount.
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Description
Explore the foundational concepts of genetics through Mendel's groundbreaking experiments with pea plants. This quiz covers his laws of inheritance, including the Law of Segregation and hybridization principles. Test your understanding of how traits are inherited and the significance of dominant and recessive alleles.
