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Questions and Answers
What is the law of segregation?
What is a gene?
An inherited factor on the chromosome responsible for a trait.
What does genotype refer to?
The genetic constitution of an individual.
A genotype with two identical alleles is called _____?
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The physical appearance of an organism as a result of its genotype is called _____?
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A recessive gene is expressed in the presence of another allele.
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What is an example of hybridization?
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What is the purpose of a Punnett square?
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The offspring of a PPL and pp cross will produce the first filial generation known as _____?
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What phenotypic ratio results from a Pp x Pp genetic cross?
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Co-dominance means that both alleles are fully expressed in the phenotype.
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Which of these is an example of a gene interaction?
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Study Notes
Mendelian Genetics Overview
- Genes are inherited factors located on chromosomes, responsible for specific traits.
- The locus refers to the fixed position of a gene on a chromosome.
- Genotype is the genetic constitution of an individual, while alleles are alternative forms of a gene.
Allele Variations and Dominance
- Complete dominance occurs when one dominant allele is sufficient to express the dominant trait, resulting in a 3:1 phenotypic ratio in monohybrid crosses.
- Incomplete dominance shows a blending of traits, producing a phenotype that is intermediate.
- Co-dominance occurs when both alleles in a heterozygote are fully expressed.
Key Laws of Mendel's Genetics
- Law of Segregation: Alleles for a gene separate during meiosis, ensuring offspring inherit one allele from each parent.
- Law of Independent Assortment: Alleles of different genes segregate independently from one another.
Genetic Interaction Mechanisms
- Lethal genes can result in the death of individuals carrying certain allele combinations.
- Non-allelic interactions, including epistasis, can modify phenotypic ratios.
- Complementary gene action requires two different genes to express a phenotype.
- Duplicate gene action indicates that multiple genes can contribute to a single trait.
Hybridization and Generations
- Hybridization is the cross between two individuals with contrasting traits (e.g., purple vs. white flowers).
- The F1 generation is the first offspring from a cross of two homozygous parents with differing traits.
- The F2 generation arises from self-fertilization or sibling mating of F1 individuals.
Genetic Terminology
- Homozygous: An individual with two identical alleles for a given gene.
- Heterozygous: An individual with two different alleles for a given gene.
- Backcrossing involves crossing a heterozygote with one of its homozygous parents for trait analysis.
Mendel's Experiments
- Mendel conducted experiments using self-pollinated Pisum sativum (green peas).
- He employed pure line or true breeding parents to analyze traits.
- Emasculation was performed to prevent self-fertilization, allowing for controlled crosses.
Punnett Square Analysis
- The Punnett Square visualizes genetic crosses, displaying potential offspring genotypes.
- Example cross: Pp x Pp yields:
- Genotypic Ratio: 1 PP : 2 Pp : 1 pp
- Phenotypic Ratio: 3 purple : 1 white
Conclusion
- Mendel's principles form the foundation of modern genetics, with clear definitions for alleles, dominance, and inheritance patterns, vital for understanding genetic variation and trait distribution.
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Description
Explore the fundamental principles of Mendelian genetics, including the concepts of genotype, alleles, and inheritance laws. Understand the mechanisms of dominance, including complete dominance, incomplete dominance, and co-dominance. This quiz will enhance your knowledge of how traits are passed down through generations.
