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Questions and Answers
What ratio is observed in the F2 generation of the sweet pea flower color cross?
What ratio is observed in the F2 generation of the sweet pea flower color cross?
- 3:1
- 1:1:1:1
- 9:3:3:1
- 9:7 (correct)
What type of genetic interaction is described when recessive alleles at either of two loci can mask the expression of dominant alleles?
What type of genetic interaction is described when recessive alleles at either of two loci can mask the expression of dominant alleles?
- Incomplete dominance
- Duplicate recessive epistasis (correct)
- Codominance
- Epistatic dominance
In the context of the flower color cross in sweet peas, what phenotype results from the combination of dominant alleles A and B?
In the context of the flower color cross in sweet peas, what phenotype results from the combination of dominant alleles A and B?
- White flowers
- Purple flowers (correct)
- Orange flowers
- Pink flowers
Which phenotype represents the homozygous recessive condition in the sweet pea flower color example?
Which phenotype represents the homozygous recessive condition in the sweet pea flower color example?
What is the phenotypic ratio observed in the F2 generation of the awned and awnless plant cross?
What is the phenotypic ratio observed in the F2 generation of the awned and awnless plant cross?
During the F1 interbreeding of purple and white sweet pea plants, which phenotypes appear in the resulting F2 generation?
During the F1 interbreeding of purple and white sweet pea plants, which phenotypes appear in the resulting F2 generation?
What does duplicate dominant epistasis refer to in this context?
What does duplicate dominant epistasis refer to in this context?
In the described genetic cross, what is the genotype of the offspring that do not exhibit the awn character?
In the described genetic cross, what is the genotype of the offspring that do not exhibit the awn character?
Which of the following genotypes would guarantee the development of an awn in the plants?
Which of the following genotypes would guarantee the development of an awn in the plants?
Which statement correctly describes the outcome of the cross between the awned and awnless strains?
Which statement correctly describes the outcome of the cross between the awned and awnless strains?
What is the term used for the gene that masks the effect of another gene?
What is the term used for the gene that masks the effect of another gene?
Which type of gene action results in a phenotypic ratio of 9:3:4?
Which type of gene action results in a phenotypic ratio of 9:3:4?
What phenotype results from the cross of a rose comb and single comb fowl?
What phenotype results from the cross of a rose comb and single comb fowl?
What is the expected phenotypic ratio in the F2 generation from dihybrid crosses?
What is the expected phenotypic ratio in the F2 generation from dihybrid crosses?
Which statement correctly describes interallelic interaction?
Which statement correctly describes interallelic interaction?
In which type of epistasis is the phenotype expressed in the ratio of 12:3:1?
In which type of epistasis is the phenotype expressed in the ratio of 12:3:1?
What is the result of mating a pea combed fowl with a single combed fowl?
What is the result of mating a pea combed fowl with a single combed fowl?
Which gene is associated with the walnut comb phenotype?
Which gene is associated with the walnut comb phenotype?
What is transgressive segregation?
What is transgressive segregation?
What does expressivity refer to in genetics?
What does expressivity refer to in genetics?
How is penetrance defined?
How is penetrance defined?
In the case of polydactyly, what can be said about its penetrance?
In the case of polydactyly, what can be said about its penetrance?
Which statement accurately describes atavism?
Which statement accurately describes atavism?
What is the phenotypic ratio of awned to awnless rice in the cross between AAbb and aaBB?
What is the phenotypic ratio of awned to awnless rice in the cross between AAbb and aaBB?
In the context of inhibitory gene action, what color do the F1 plants exhibit when crossing IIpp with iiPP?
In the context of inhibitory gene action, what color do the F1 plants exhibit when crossing IIpp with iiPP?
What can be inferred about genes with incomplete expressivity?
What can be inferred about genes with incomplete expressivity?
What would be a phenotype with complete penetrance?
What would be a phenotype with complete penetrance?
How many phenotypic categories are observed in the F2 generation of the green and purple plant cross?
How many phenotypic categories are observed in the F2 generation of the green and purple plant cross?
What might be an example of incomplete penetrance?
What might be an example of incomplete penetrance?
What is the phenotypic ratio seen in the F2 generation when green and purple plants are crossed under inhibitory gene action?
What is the phenotypic ratio seen in the F2 generation when green and purple plants are crossed under inhibitory gene action?
Which of the following correctly describes the relationship between the dominant gene I and the purple gene P?
Which of the following correctly describes the relationship between the dominant gene I and the purple gene P?
What is the genotype of the green color in plants produced by crossing IIpp and iiPP?
What is the genotype of the green color in plants produced by crossing IIpp and iiPP?
What type of gene action is described as a dominant allele at one locus masking the expression of alleles at a second locus?
What type of gene action is described as a dominant allele at one locus masking the expression of alleles at a second locus?
In the cross between green and purple plants, what are the genotypic combinations of the offspring?
In the cross between green and purple plants, what are the genotypic combinations of the offspring?
What ratio is observed among the offspring when white and yellow fruits are crossed?
What ratio is observed among the offspring when white and yellow fruits are crossed?
Which term describes genes that enhance or reduce the effects of a major gene?
Which term describes genes that enhance or reduce the effects of a major gene?
What type of character is typically governed by one or more major genes or oligogenes?
What type of character is typically governed by one or more major genes or oligogenes?
Which aspect of the piebald spotting in animals involves modifying factors that enhance the spotting gene?
Which aspect of the piebald spotting in animals involves modifying factors that enhance the spotting gene?
Which of the following is considered a major gene controlling a specific trait?
Which of the following is considered a major gene controlling a specific trait?
Which statement about quantitative characters is true?
Which statement about quantitative characters is true?
What role do minor genes play in the expression of traits?
What role do minor genes play in the expression of traits?
Which statement accurately reflects the concept of polygenes?
Which statement accurately reflects the concept of polygenes?
Flashcards
Duplicate Recessive Epistasis
Duplicate Recessive Epistasis
A type of gene interaction where two recessive alleles at different loci mask the expression of dominant alleles at both loci, resulting in a specific phenotype.
Complimentary Gene Action
Complimentary Gene Action
A situation where both loci have recessive alleles that, when present together, prevent the expression of dominant alleles at either locus.
9:7 Phenotypic Ratio
9:7 Phenotypic Ratio
The phenotypic ratio observed in the F2 generation when duplicate recessive epistasis is occurring.
Sweet Pea Flower Color
Sweet Pea Flower Color
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Epistasis
Epistasis
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Interallelic interaction
Interallelic interaction
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Epistatic gene
Epistatic gene
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Hypostatic gene
Hypostatic gene
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Recessive epistasis
Recessive epistasis
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Dominant epistasis
Dominant epistasis
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Dihybrid inheritance
Dihybrid inheritance
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Complementary gene interaction
Complementary gene interaction
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Rose comb, pea comb, walnut comb, single comb
Rose comb, pea comb, walnut comb, single comb
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Duplicate Dominant Epistasis
Duplicate Dominant Epistasis
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Duplicate Gene Action
Duplicate Gene Action
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Locus
Locus
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Polygenic Trait
Polygenic Trait
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Inhibitory Gene Action
Inhibitory Gene Action
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13:3 Ratio
13:3 Ratio
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Rice Awned vs Awnless
Rice Awned vs Awnless
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Awned Rice Gene
Awned Rice Gene
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Rice Color Example
Rice Color Example
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Supplementary Gene Action
Supplementary Gene Action
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9:7 Ratio
9:7 Ratio
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Modifying Genes
Modifying Genes
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Major vs. Minor Genes
Major vs. Minor Genes
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Qualitative Characters
Qualitative Characters
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Quantitative Characters
Quantitative Characters
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Polygenes
Polygenes
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Inheritance of Quantitative Characters
Inheritance of Quantitative Characters
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Modifying Alleles
Modifying Alleles
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Allelic Series
Allelic Series
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Expressivity
Expressivity
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Penetrance
Penetrance
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Transgressive Segregation
Transgressive Segregation
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Polydactyly
Polydactyly
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Incomplete penetrance
Incomplete penetrance
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Complete expressivity
Complete expressivity
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Complete penetrance
Complete penetrance
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Expressivity
Expressivity
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Study Notes
Types of Gene Action
- Gene interaction can be intra-allelic (within the same allele) or interallelic (between different alleles).
- Interallelic interaction is called epistasis.
- Epistatic genes mask the effects of other genes.
- Hypostatic genes have their effects masked by epistatic genes.
- Epistasis modifies the expected phenotypic ratios.
- Examples of epistatic gene interactions include recessive epistasis (9:3:4), dominant epistasis (12:3:1), dominant and recessive epistasis (13:3), duplicate recessive epistasis (9:7), duplicate dominant epistasis (15:1), and polymeric gene interaction (9:6:1).
Dihybrid Ratio
- A classical example of gene interaction is the dihybrid ratio (9:3:3:1) in fowls, influencing comb shape.
Comb Shape in Fowls
- Different breeds of poultry have different comb shapes (e.g., rose, pea, single, walnut).
- Comb shape is controlled by multiple genes, showcasing gene interaction.
- Crosses between different comb types show specific ratios in the F2 generation.
Duplicate Recessive Epistasis (Complimentary Gene Action)
- Recessive alleles at two loci can mask the dominant alleles' expression in flower colour.
- A classic example is the purple colour in sweet peas.
- Lack of both dominant alleles results in white flower colour.
- This scenario causes a 9:7 phenotypic ratio in the F2 generation.
Duplicate Gene Action (15:1) (Duplicate Dominant Epistasis)
- A dominant allele at either of two loci can mask the expression of recessive alleles.
- Awn (hairs) presence in rice is affected by two dominant alleles.
- Awnless trait appears only when both alleles are recessive.
- This leads to a 15:1 F2 phenotypic ratio.
Inhibitory Gene Action (13:3)
- A dominant allele at one locus can mask the expression of both dominant and recessive alleles at another locus.
- An example in rice plants involves green (I) and purple (P) colour expression.
- In homozygous recessives, the 13:3 F2 phenotypic ratio is observed.
Supplementary Gene Action (Recessive Epistasis)
- One dominant gene has a role and another affects the phenotype's expression.
- For instance, in wheat with purple or red colours or white.
- A specific phenotypic ratio is observed in the F2 generation (9:3:4).
Additive Factors (Polymeric Gene Action)
- Two or more genes can cumulatively influence a phenotype.
- Example with length of awns (hairs) in barley
- The combined effect results in an additive effect on the phenotype's expression.
- This often shows a 9:6:1 F2 phenotypic ratio in barley, when two genes influence awn length.
Dominant Epistasis (12:3:1)
- A dominant allele at one locus can mask the expression of alleles at another locus.
- Demonstrated in fruit colour, a dominant gene W masks the expression of yellow or green coloration.
Modifying Genes
- Modifying genes influence the phenotypic effect of a major gene.
- Their effect is cumulative or additive.
- They can enhance or reduce a phenotype.
- They are crucial in creating continuous variation in traits like spotting in animals.
Inheritance of Quantitative Characters (Polygenes)
- Quantitative traits (e.g., height, grain yield) show continuous variation.
- Multiple genes (polygenes) influence these traits.
- Environmental factors also impact quantitative traits.
Transgressive Segregation
- Offspring in the F2 generation can show phenotypes outside the parental range.
- Due to the segregation of alleles producing positive effects,
- This can result in either higher or lower intensities of the trait.
Expressivity
- The degree of a gene's phenotype expression.
- Can vary even when the genotype is the same
- Indicates how consistently the gene affects the phenotype.
Penetrance
- The proportion of individuals with a specific genotype that express the corresponding phenotype.
- Can be complete, or incomplete.
Polydactyly
- Polydactyly is an example of a condition with extra digits.
- It's sometimes influenced by a dominant or incompletely dominant gene.
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Description
Test your knowledge on the genetic crosses of sweet pea flowers, focusing on flower color and plant characteristics. This quiz covers phenotypic ratios in F2 generations, genetic interactions, and the effects of alleles. Dive into the fascinating world of plant genetics and find out how dominant and recessive traits manifest!
