Domanda del libro di testo
Write a short essay that discusses the difference between the more traditional Mendelian and neo-Mendelian modes of inheritance (qualitative inheritance) and quantitative inheritance.
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Ch. 25 - Quantitative Genetics and Multifactorial Traits
Klug12th EditionConcepts of GeneticsISBN: 9780135564776
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TOC.tableOfContents
- Ch. 1 - Introduction to Genetics17
- Ch. 2 - Mitosis and Meiosis36
- Ch. 3 - Mendelian Genetics51
- Ch. 4 - Extensions of Mendelian Genetics74
- Ch. 5 - Chromosome Mapping in Eukaryotes51
- Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages46
- Ch. 7 - Sex Determination and Sex Chromosomes33
- Ch. 8 - Chromosome Mutations: Variation in Number and Arrangement40
- Ch. 9 - Extranuclear Inheritance31
- Ch. 10 - DNA Structure and Analysis43
- Ch. 11 - DNA Replication and Recombination44
- Ch. 12 - DNA Organization in Chromosomes30
- Ch. 13 - The Genetic Code and Transcription54
- Ch. 14 - Translation and Proteins47
- Ch. 15 - Gene Mutation, DNA Repair, and Transposition41
- Ch. 16 - Regulation of Gene Expression in Bacteria29
- Ch. 17 - Transcriptional Regulation in Eukaryotes41
- Ch. 18 - Post-transcriptional Regulation in Eukaryotes33
- Ch. 19 - Epigenetics33
- Ch. 20 - Recombinant DNA Technology44
- Ch. 21 - Genomic Analysis36
- Ch. 22 - Applications of Genetic Engineering and Biotechnology36
- Ch. 23 - Developmental Genetics37
- Ch. 24 - Cancer Genetics34
- Ch. 25 - Quantitative Genetics and Multifactorial Traits54
- Ch. 26 - Population and Evolutionary Genetics45
Klug12th EditionConcepts of GeneticsISBN: 9780135564776Non è quello che usi tu?Cambia libro di testo
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Klug 12th EditionCh. 25 - Quantitative Genetics and Multifactorial TraitsProblema 4a
Klug 12th EditionCh. 25 - Quantitative Genetics and Multifactorial TraitsProblema 4aCapitolo 25, Problema 4a
A dark-red strain and a white strain of wheat are crossed and produce an intermediate, medium-red F₁. When the F₁ plants are interbred, an F₂ generation is produced in a ratio of 1 dark-red: 4 medium-dark-red: 6 medium-red: 4 light-red: 1 white. Further crosses reveal that the dark-red and white F₂ plants are true breeding
Based on the ratios in the F₂ population, how many genes are involved in the production of color?
Guida verificata passo dopo passo1
Recognize that the F₁ generation shows an intermediate phenotype (medium-red) between the two parental strains (dark-red and white), which suggests incomplete dominance or additive gene action rather than simple dominance.
Examine the F₂ phenotypic ratio given: 1 dark-red : 4 medium-dark-red : 6 medium-red : 4 light-red : 1 white. Notice that this ratio resembles the expansion of a binomial expression raised to the fourth power, which hints at multiple genes contributing additively to the trait.
Recall that when multiple genes contribute additively to a trait, the F₂ phenotypic ratios often follow the pattern of the coefficients in the expansion of \((a + b)^n\), where \(n\) is the number of genes involved. The coefficients for \((a + b)^4\) are 1, 4, 6, 4, 1, matching the observed ratio.
Conclude that the number of genes involved corresponds to the exponent \(n\) in the binomial expansion that fits the observed ratio. Here, since the ratio matches the coefficients of \((a + b)^4\), it suggests that 4 genes are involved in producing the color.
Confirm this conclusion by considering that the dark-red and white F₂ plants are true breeding, indicating homozygosity at all loci, which aligns with the idea of multiple additive genes segregating independently.
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Incomplete Dominance and Intermediate Phenotypes
Incomplete dominance occurs when heterozygous individuals display a phenotype intermediate between the two homozygous parents. In this question, the F₁ generation shows a medium-red color, which is between dark-red and white, indicating that neither allele is completely dominant. This concept helps explain the blending of traits seen in the offspring.
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04:37
Variations on Dominance
Polygenic Inheritance and Quantitative Trait Ratios
Polygenic inheritance involves multiple genes contributing additively to a single trait, producing a range of phenotypes. The complex F₂ ratio (1:4:6:4:1) suggests several genes influence wheat color, with each gene adding to the pigment intensity. Recognizing this pattern helps determine the number of genes involved based on the distribution of phenotypes.
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13:40Traits and Variance
True Breeding and Homozygosity
True breeding plants consistently produce offspring with the same phenotype, indicating homozygosity for the genes controlling that trait. The fact that dark-red and white F₂ plants are true breeding means they are homozygous for all relevant alleles, which is crucial for interpreting the genetic ratios and confirming the number of genes involved.
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13:04Hardy Weinberg
Pratica correlata
Domanda del libro di testo
How do we know that monozygotic twins are not identical genotypically as adults?
493
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Domanda del libro di testo
Define the following:
(a) Polygenic
(b) Additive alleles
(c) Correlation
(d) Monozygotic and dizygotic twins
(e) Heritability
(f) QTL
(g) Continuous variation
625
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Domanda del libro di testo
A dark-red strain and a white strain of wheat are crossed and produce an intermediate, medium-red F₁. When the F₁ plants are interbred, an F₂ generation is produced in a ratio of 1 dark-red: 4 medium-dark-red: 6 medium-red: 4 light-red: 1 white. Further crosses reveal that the dark-red and white F₂ plants are true breeding
Predict the outcome of the F1 and F2 generations in a cross between a true-breeding medium-red plant and a white plant.
722
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Domanda del libro di testo
A dark-red strain and a white strain of wheat are crossed and produce an intermediate, medium-red F₁. When the F₁ plants are interbred, an F₂ generation is produced in a ratio of 1 dark-red: 4 medium-dark-red: 6 medium-red: 4 light-red: 1 white. Further crosses reveal that the dark-red and white F₂ plants are true breeding
Assign symbols to these alleles, and list possible genotypes that give rise to the medium-red and light-red phenotypes.
503
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Domanda del libro di testo
A dark-red strain and a white strain of wheat are crossed and produce an intermediate, medium-red F₁. When the F₁ plants are interbred, an F₂ generation is produced in a ratio of 1 dark-red: 4 medium-dark-red: 6 medium-red: 4 light-red: 1 white. Further crosses reveal that the dark-red and white F₂ plants are true breeding
How many additive alleles are needed to produce each possible phenotype?
438
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