Domanda del libro di testo
In analyzing genetic data, how do we know whether deviation from the expected ratio is due to chance rather than to another, independent factor?
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Ch. 3 - Mendelian Genetics
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
Capitolo 3, Problema 1b
How do we know whether an organism expressing a dominant trait is homozygous or heterozygous?
Guida verificata passo dopo passo1
Understand that an organism expressing a dominant trait can have two possible genotypes: homozygous dominant (e.g., \(AA\)) or heterozygous (e.g., \(Aa\)). Both genotypes show the dominant phenotype, so phenotype alone does not distinguish them.
Perform a test cross by mating the organism with a homozygous recessive individual (e.g., \(aa\)), which will only contribute recessive alleles to the offspring.
Analyze the offspring phenotypes: if all offspring show the dominant trait, the tested organism is likely homozygous dominant; if some offspring show the recessive trait, the tested organism is heterozygous.
Use the expected Mendelian ratios to predict offspring genotypes and phenotypes from the test cross: for a heterozygous parent (\(Aa\)) crossed with \(aa\), expect approximately 50% dominant and 50% recessive offspring.
Conclude the genotype of the original organism based on the presence or absence of recessive phenotype offspring in the test cross.
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Dominant and Recessive Alleles
Dominant alleles express their trait even if only one copy is present, while recessive alleles require two copies to show their trait. Understanding this helps distinguish between organisms that show a dominant trait due to one or two dominant alleles.
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Percorso guidato
04:37
Variations on Dominance
Genotype vs. Phenotype
Phenotype is the observable trait, while genotype is the genetic makeup. An organism with a dominant phenotype could have either a homozygous dominant or heterozygous genotype, so knowing the difference is key to identifying the underlying genetic composition.
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Percorso guidato
07:52Gamete Genotypes
Test Cross
A test cross involves breeding the organism with a homozygous recessive individual to determine its genotype. If any offspring show the recessive trait, the tested organism is heterozygous; if all offspring show the dominant trait, it is likely homozygous dominant.
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Percorso guidato
26:08Trihybrid Cross
Pratica correlata
Domanda del libro di testo
Write a short essay that correlates Mendel's four postulates with what is now known about genes, alleles, and homologous chromosomes.
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Domanda del libro di testo
Since experimental crosses are not performed in humans, how do we know how traits are inherited?
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Domanda del libro di testo
How was Mendel able to derive postulates concerning the behavior of 'unit factors' during gamete formation when he could not directly observe them?
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