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Questions and Answers
What does a genotype represent in an organism?
What does a genotype represent in an organism?
Which of the following best describes a phenotype?
Which of the following best describes a phenotype?
What is the ultimate source of variation that fuels natural selection?
What is the ultimate source of variation that fuels natural selection?
How is the relationship between genotype and phenotype often characterized?
How is the relationship between genotype and phenotype often characterized?
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Which factor does NOT influence phenotype?
Which factor does NOT influence phenotype?
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What is a characteristic of Neurofibromatosis-1?
What is a characteristic of Neurofibromatosis-1?
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What relationship does Mendel's law of independent assortment describe?
What relationship does Mendel's law of independent assortment describe?
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Which concept explains that one gene can affect many traits?
Which concept explains that one gene can affect many traits?
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What does epistasis refer to in genetics?
What does epistasis refer to in genetics?
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Which term is used to describe traits that are controlled by multiple genes?
Which term is used to describe traits that are controlled by multiple genes?
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How does the relationship between genotype and phenotype typically appear?
How does the relationship between genotype and phenotype typically appear?
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In the context of genetics, what does polygenic inheritance imply?
In the context of genetics, what does polygenic inheritance imply?
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What can lead to potential blindness as a complication?
What can lead to potential blindness as a complication?
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What type of genetic variation can cause a premature stop in translation?
What type of genetic variation can cause a premature stop in translation?
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Which type of mutation is characterized by a shift in the reading frame due to base changes?
Which type of mutation is characterized by a shift in the reading frame due to base changes?
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What type of chromosomal rearrangement is associated with Huntington’s chorea?
What type of chromosomal rearrangement is associated with Huntington’s chorea?
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What genetic disorder is commonly caused by non-disjunction?
What genetic disorder is commonly caused by non-disjunction?
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Which of the following best describes a deletion mutation?
Which of the following best describes a deletion mutation?
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Which genetic variation can directly result in an organism possessing XY sex chromosomes but presenting as female?
Which genetic variation can directly result in an organism possessing XY sex chromosomes but presenting as female?
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In terms of genetic variation, what does the term 'inversion' refer to?
In terms of genetic variation, what does the term 'inversion' refer to?
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How do identical twins' fingerprints demonstrate the complexity of genotype-phenotype relationships?
How do identical twins' fingerprints demonstrate the complexity of genotype-phenotype relationships?
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Which type of mutation results from a single nucleotide substitution?
Which type of mutation results from a single nucleotide substitution?
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What is a significant source of genetic variation during reproduction?
What is a significant source of genetic variation during reproduction?
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Which type of mutation leads to a change in the amino acid sequence of a protein?
Which type of mutation leads to a change in the amino acid sequence of a protein?
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What is the 'Norm of Reaction'?
What is the 'Norm of Reaction'?
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Which of the following is NOT a known cause of mutation?
Which of the following is NOT a known cause of mutation?
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What is the effect of a silent mutation?
What is the effect of a silent mutation?
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Which condition is an example of a disease caused by a point mutation?
Which condition is an example of a disease caused by a point mutation?
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How is phenylketonuria (PKU) an example of genotype-phenotype interaction?
How is phenylketonuria (PKU) an example of genotype-phenotype interaction?
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Study Notes
Types of Variation
- Genotypes, phenotypes, and evolution
- Relationship between genotype and phenotype is sometimes simple, sometimes complex
- Complete dominance
- Example: Neurofibromatosis-1 (excessive tissue growth along nerves, potential blindness)
- Incomplete dominance
- Example: Flower color inheritance (red x white = pink)
Genotype and Phenotype
- Trait: Characteristics of an organism (e.g., eye color, hair color, seed shape)
- Genotype: Genetic makeup of an organism
- Phenotype: Observable features of an organism
Relationship Between Genotype and Phenotype
- Complex relationship: One gene can affect many traits (pleiotropy)
- Example: Coloration and crossed eyes in Siamese cats; Marfan syndrome
Sources of Genetic Variation
- Recombination and independent assortment: Reshuffling of existing variation
- Mutation:
- Errors in DNA repair or synthesis
- Damage by X-rays or chemicals
- Unequal crossing over
- Errors in meiosis
- Point mutations:
- Substitution (silent - same amino acid, missense - wrong amino acid)
- Examples: sickle cell anemia, osteogenesis imperfecta
- Larger-scale chromosomal rearrangements:
- Deletion
- Duplication
- Inversion
- Translocation (e.g., SRY gene -> XX males)
- Chromosome number:
- Non-disjunction (e.g., Down syndrome)
- Polyploidy
Environment and Phenotype
- Environment influences phenotype
- Example: height, Phenylketonuria (PKU)
- Norm of reaction: A very important concept
Summary
- Relationship between genotype and phenotype is complex.
- Truly Mendelian inheritance is a small subset.
- Recombination and independent assortment create new combinations.
- Variation arises from mutations.
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Description
Explore the intricacies of genetic variation through this quiz on genotypes, phenotypes, and the relationship between them. Delve into complete and incomplete dominance while examining real-world examples like neurofibromatosis-1 and flower color inheritance. Understand the sources of genetic variation and how traits are expressed in organisms.
