Podcast
Questions and Answers
What defines incomplete dominance in genetic inheritance?
What defines incomplete dominance in genetic inheritance?
Which concept involves a single gene affecting multiple traits?
Which concept involves a single gene affecting multiple traits?
Which of the following describes codominance?
Which of the following describes codominance?
Which of the following examples illustrates multiple alleles?
Which of the following examples illustrates multiple alleles?
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What effect can environmental factors have on gene expression?
What effect can environmental factors have on gene expression?
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Which scenario best exemplifies lethal alleles?
Which scenario best exemplifies lethal alleles?
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Which is a characteristic of polygenic inheritance?
Which is a characteristic of polygenic inheritance?
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Which example illustrates how gene interaction can alter phenotypic ratios?
Which example illustrates how gene interaction can alter phenotypic ratios?
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Why might Mendel’s laws not be observed in certain genetic scenarios?
Why might Mendel’s laws not be observed in certain genetic scenarios?
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What is the phenotype of a mouse with the genotype AY/A?
What is the phenotype of a mouse with the genotype AY/A?
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Which statement about the yellow allele (AY) in mice is true?
Which statement about the yellow allele (AY) in mice is true?
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Which of the following ratios represents the modified dihybrid ratio when one gene locus exhibits codominance?
Which of the following ratios represents the modified dihybrid ratio when one gene locus exhibits codominance?
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Which allele combinations produce a 1:2:1:2:4:2:1:2:1 ratio in inheritance patterns?
Which allele combinations produce a 1:2:1:2:4:2:1:2:1 ratio in inheritance patterns?
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What phenotypic ratio arises from a dihybrid cross involving one dominant and one recessive allele at one locus and codominant alleles at another?
What phenotypic ratio arises from a dihybrid cross involving one dominant and one recessive allele at one locus and codominant alleles at another?
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Which of the following represents a situation of a lethal allele?
Which of the following represents a situation of a lethal allele?
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What type of inheritance pattern is seen in the ABO blood group system?
What type of inheritance pattern is seen in the ABO blood group system?
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What is the expected phenotype for a genotype of AB in the ABO blood grouping system?
What is the expected phenotype for a genotype of AB in the ABO blood grouping system?
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In the context of snapdragons, which trait exhibits incomplete dominance?
In the context of snapdragons, which trait exhibits incomplete dominance?
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What is true about the presence of homozygous yellow mice?
What is true about the presence of homozygous yellow mice?
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What is the genotypic ratio of the F2 generation when crossing red and white snapdragons?
What is the genotypic ratio of the F2 generation when crossing red and white snapdragons?
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What phenotype results from the cross between a homozygous black feathered fowl and a homozygous splashed white feathered fowl?
What phenotype results from the cross between a homozygous black feathered fowl and a homozygous splashed white feathered fowl?
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In the context of snapdragons, which term best describes the expression of alleles when pink flowers are produced from red and white parents?
In the context of snapdragons, which term best describes the expression of alleles when pink flowers are produced from red and white parents?
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What ratio is generally expected in the offspring when a lethal gene is involved in a cross?
What ratio is generally expected in the offspring when a lethal gene is involved in a cross?
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What is the outcome when red and white cattle are crossed with respect to coat color?
What is the outcome when red and white cattle are crossed with respect to coat color?
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For a mutation resulting in a nonfunctional gene product, what occurs in the homozygous recessive individuals?
For a mutation resulting in a nonfunctional gene product, what occurs in the homozygous recessive individuals?
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In the case of palomino horses, what genetic interaction is primarily illustrated?
In the case of palomino horses, what genetic interaction is primarily illustrated?
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Which phenomenon allows for both alleles to be expressed in offspring from red and white parent plants?
Which phenomenon allows for both alleles to be expressed in offspring from red and white parent plants?
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When yellow-coated mice exhibit a wild-type coat pattern, what is the expected offspring ratio from a cross between two yellow-coated mice?
When yellow-coated mice exhibit a wild-type coat pattern, what is the expected offspring ratio from a cross between two yellow-coated mice?
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What do heterozygotes of a recessive lethal allele express phenotypically?
What do heterozygotes of a recessive lethal allele express phenotypically?
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Study Notes
Non-Mendelian Inheritance
- Non-Mendelian inheritance refers to variations on Mendel's laws, where inheritance patterns don't always follow the typical dominant/recessive pairings.
- Key types of Non-Mendelian inheritance include:
- Incomplete dominance
- Codominance
- Lethal alleles
- Multiple alleles
- Polygenic inheritance
- Pleiotropy
- Environmental factors
- Gene interaction
Incomplete Dominance
- Neither allele is completely dominant over the other.
- The heterozygous phenotype is an intermediate between the two homozygous phenotypes.
- Example: Pink snapdragons resulting from a cross between red and white snapdragons.
Codominance
- Both alleles in the heterozygote are fully and separately expressed.
- Example: Roan cattle that exhibit both red and white hairs.
Lethal Alleles
- Alleles that cause the death of the organism that carries them.
- Often recessive, only expressed in homozygous state.
- Example: in mice, the yellow coat allele (AY) is dominant to the normal agouti allele (A), heterozygotes are yellow. However, homozygous AY mice die before birth
Multiple Alleles
- More than two alleles for a gene at a particular locus exist within a population.
- Only two alleles are present in any single individual.
- Example: ABO blood groups (IA, IB, i).
Polygenic Inheritance
- Multiple genes contribute to a single trait.
- Example: Human height, skin color.
Pleiotropy
- A single gene affects multiple traits.
- Example: Sickle cell anaemia affects red blood cells, causing anaemia, and also affects the function of other organs.
Environmental Factors
- Environmental factors can influence the expression of a gene.
- Example: Siamese cats express different fur colors based on temperature.
Gene Interaction
- Products of genes interact to modify genetic ratios from the expected Mendelian ratios.
- Different genes can influence one particular trait.
- Example: The production of a purple pigment in corn shows gene interaction between various genes
Extensions to Mendel (Summary)
- Mendel's laws don't always perfectly predict inheritance patterns in all cases.
- Various situations exist where inheritance outcomes are different from the 9:3:3:1 ratio.
- Incomplete dominance, codominance, lethal alleles, multiple alleles, gene interaction and environmental factors all play a role in non-Mendelian inheritance.
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Description
Test your understanding of non-Mendelian inheritance patterns, including concepts like incomplete dominance, codominance, and lethal alleles. Explore how these patterns differ from traditional Mendelian genetics and see real-world examples. Perfect for biology students looking to deepen their knowledge on this fascinating topic.
