Domanda del libro di testo
How do we know that X chromosomal inactivation of either the paternal or maternal homolog is a random event during early development in mammalian females?
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Ch. 7 - Sex Determination and Sex Chromosomes
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 7, Problema 1c
How do we know that Drosophila utilizes a different sex-determination mechanism than mammals, even though it has the same sex-chromosome compositions in males and females?
Guida verificata passo dopo passo1
Step 1: Understand the sex chromosome compositions in both mammals and Drosophila. In mammals, females are XX and males are XY, while in Drosophila, females are also XX and males are XY.
Step 2: Recognize that despite having the same chromosomal notation (XX for females and XY for males), the mechanism that determines sex differs between the two organisms.
Step 3: Learn that in mammals, the presence of the Y chromosome, specifically the SRY gene on the Y chromosome, triggers male development, making the Y chromosome the key determinant of sex.
Step 4: In contrast, Drosophila determines sex based on the ratio of X chromosomes to sets of autosomes (the X:A ratio), not simply the presence or absence of the Y chromosome. The Y chromosome in Drosophila is not the primary sex determinant but is required for male fertility.
Step 5: Conclude that the difference in sex-determination mechanisms is evident because mammals rely on a dominant Y-linked gene, whereas Drosophila relies on the X:A ratio, demonstrating that identical sex chromosome compositions can lead to different sex-determination systems.
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Sex-Determination Mechanisms
Sex-determination mechanisms are biological systems that dictate an organism's sex. While mammals use the presence of the Y chromosome (XY males, XX females) to determine sex, Drosophila relies on the ratio of X chromosomes to sets of autosomes, not just the presence of a Y chromosome.
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04:24
Sex Determination
Chromosomal Composition in Drosophila vs. Mammals
Both Drosophila and mammals have XY males and XX females, but in Drosophila, the Y chromosome is not the primary determinant of maleness. Instead, the X:A ratio (number of X chromosomes to autosome sets) controls sex, whereas in mammals, the Y chromosome carries the SRY gene that triggers male development.
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10:35Human Sex Chromosomes
Genetic and Molecular Evidence for Sex Determination
Experimental studies, such as chromosome manipulation and gene expression analysis, show that altering the X:A ratio in Drosophila changes sex phenotype regardless of Y presence. In contrast, mammals require the SRY gene on the Y chromosome for male development, demonstrating distinct molecular pathways despite similar chromosome types.
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04:24Sex Determination
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