Domanda del libro di testo
How do mammals, including humans, solve the 'dosage problem' caused by the presence of an X and Y chromosome in one sex and two X chromosomes in the other sex?
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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 9
Describe how nondisjunction in human female gametes can give rise to Klinefelter and Turner syndrome offspring following fertilization by a normal male gamete.
Guida verificata passo dopo passo1
Understand that nondisjunction is the failure of chromosome pairs to separate properly during meiosis, resulting in gametes with abnormal numbers of chromosomes.
Recognize that in human females, nondisjunction can occur during meiosis I or II, leading to eggs that either have two X chromosomes (XX) or no sex chromosome (O).
Consider fertilization by a normal male gamete, which always contributes one X or one Y chromosome.
For Klinefelter syndrome (typically XXY), an egg with two X chromosomes (due to nondisjunction) is fertilized by a sperm carrying a Y chromosome, resulting in an XXY zygote.
For Turner syndrome (typically XO), an egg with no sex chromosome (due to nondisjunction) is fertilized by a sperm carrying an X chromosome, resulting in an XO zygote.
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Nondisjunction
Nondisjunction is the failure of chromosome pairs to separate properly during meiosis, resulting in gametes with abnormal numbers of chromosomes. In females, this can occur during meiosis I or II, producing eggs with either an extra chromosome or missing one, which affects the chromosome number in the resulting zygote after fertilization.
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04:34
Allopolyploidy
Klinefelter Syndrome
Klinefelter syndrome occurs when a male inherits an extra X chromosome, resulting in a 47,XXY karyotype. This can happen if a female gamete with two X chromosomes (due to nondisjunction) is fertilized by a normal Y-bearing sperm, leading to the presence of an additional sex chromosome in the offspring.
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10:35Human Sex Chromosomes
Turner Syndrome
Turner syndrome arises when a female has only one X chromosome (45,X) due to the absence of a sex chromosome. This can result if a female gamete lacking an X chromosome (from nondisjunction) is fertilized by a normal X-bearing sperm, producing offspring with monosomy X and characteristic developmental features.
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10:35Human Sex Chromosomes
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Domanda del libro di testo
What specific observations (evidence) support the conclusions about sex determination in Drosophila and humans?
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Domanda del libro di testo
An insect species is discovered in which the heterogametic sex is unknown. An X-linked recessive mutation for reduced wing (rw) is discovered. Contrast the F1 and F2 generations from a cross between a female with reduced wings and a male with normal-sized wings when the female is the heterogametic sex.
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Domanda del libro di testo
When cows have twin calves of unlike sex (fraternal twins), the female twin is usually sterile and has masculinized reproductive organs. This calf is referred to as a freemartin. In cows, twins may share a common placenta and thus fetal circulation. Predict why a freemartin develops.
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Domanda del libro di testo
An insect species is discovered in which the heterogametic sex is unknown. An X-linked recessive mutation for reduced wing (rw) is discovered. Contrast the F1 and F2 generations from a cross between a female with reduced wings and a male with normal-sized wings when the male is the heterogametic sex.
467
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Domanda del libro di testo
The phenotype of an early-stage human embryo is considered sexually indifferent. Explain why this is so even though the embryo's genotypic sex is already fixed.
1156
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