45 Questions
Which chromosome does not determine sex in Drosophila?
Y chromosome
In Drosophila, what is the ratio of X chromosomes to haploid sets of autosomes in normal males?
1:2
Which theory states that the balance between X and autosomes determines sex differentiation in Drosophila?
Genic Balance Theory
Which environmental factor influences sex determination in reptiles like crocodiles and turtles?
Temperature
In reptiles with temperature-dependent sex determination, what happens at low temperatures?
100% females are produced
Which region of the Y chromosome shares homology with regions on the X chromosome and recombines with it during meiosis?
Pseudoautosomal Regions (PARs)
What is the function of the SRY gene located adjacent to the pseudoautosomal region of the Y chromosome?
Triggers testes formation
Which gene on the Y chromosome is responsible for male sex determination in mammals?
SRY gene
What is the primary sex ratio reflective of in a population?
Proportion of males to females conceived
Which region of the Y chromosome is classified as heterochromatic?
Male-specific Region of the Y (MSY)
What is the most common characteristic found in males with 47,XYY karyotype?
Subnormal intelligence
During early embryonic development, the embryo is initially hermaphroditic, which means:
The gonadal phenotype is sexually indifferent
The Y chromosome in humans has approximately how many genes?
900-1400 genes
Which chromosome is responsible for triggering the differentiation of gonadal ridges into ovaries or testes in humans?
Y chromosome
Which gene on the Y chromosome plays a crucial role in male sexual differentiation?
SRY gene
What is the primary role of the Y chromosome in determining maleness?
The Y chromosome contains genes that trigger the differentiation of the gonadal ridges into testes.
What is the primary cause of Klinefelter syndrome?
Nondisjunction during meiosis, resulting in an extra X chromosome.
What is the primary characteristic of Turner syndrome?
Female external genitalia and internal ducts but ovaries are rudimentary.
What is the most common characteristic found in males with 47,XYY karyotype?
Tall stature
What is the primary function of the pseudoautosomal region of the Y chromosome?
It shares homology with regions on the X chromosome and recombines with it during meiosis.
What is the most common karyotype associated with Triplo-X syndrome?
47,XXX
Which chromosomal phenomenon is responsible for dosage compensation between males and females?
Random X chromosome inactivation
What is the significance of Barr bodies observed in female somatic cells?
They represent the inactivated X chromosome
What is the key characteristic of individuals with Klinefelter syndrome (47,XXY)?
They have two active X chromosomes
What is the primary reason why females with Turner syndrome (45,XO) are not entirely normal?
They lack an active X chromosome
What is the primary reason why females with triple or tetra Xs (47,XXX or 48,XXXX) are not entirely normal?
They have an imbalance in X chromosome dosage
What is the primary function of the SRY gene located on the Y chromosome?
It triggers the differentiation of gonads into testes
What is the primary role of the pseudoautosomal regions (PARs) on the Y chromosome?
To facilitate synapsis and recombination with the X chromosome during meiosis
What is the role of the SRY (sex-determining region) gene on the Y chromosome?
It triggers the formation of testes during embryonic development
What is the primary cause of Klinefelter syndrome?
The presence of an extra X chromosome (47,XXY)
What is the primary cause of Turner syndrome?
The absence of a functional Y chromosome
What is the primary sex ratio reflective of in a population?
The proportion of males to females conceived
What is the primary function of the male-specific region (MSY) of the Y chromosome?
To encode proteins responsible for male sexual differentiation
What is the primary cause of the male phenotype in individuals with Klinefelter syndrome (47,XXY)?
The extra X chromosome is inactivated through a process similar to X-inactivation in females.
What is the primary reason for the tall stature observed in individuals with 47,XYY syndrome?
The extra Y chromosome carries genes that promote increased height.
What is the primary factor that triggers the differentiation of gonadal ridges into ovaries or testes during early embryonic development in humans?
The presence or absence of the Y chromosome.
In individuals with 47,XXX syndrome (Triplo-X), what is the primary reason for the observed phenotypic variability?
The degree of X-inactivation and the specific genes affected vary between individuals.
What is the primary reason for the male phenotype in individuals with a normal 46,XY karyotype?
The presence of the Y chromosome triggers male development through the SRY gene.
What is the primary reason for the observed intellectual disability in some individuals with 47,XXX syndrome (Triplo-X)?
The degree of X-inactivation and the specific genes affected vary between individuals.
What is the primary function of the XIST RNA in mammals?
It binds to and inactivates one of the X chromosomes
In Drosophila, what determines sex?
The ratio of X chromosomes to autosomes
Which of the following patterns of temperature-dependent sex determination (TSD) in reptiles is correct?
Low temperatures yield females, and high temperatures yield males
Which human chromosomal condition is associated with the presence of an extra X chromosome in females?
47,XXX syndrome (Triplo-X)
What is the primary role of the Y chromosome in human sex determination?
It triggers the differentiation of gonadal ridges into testes
Which chromosomal condition in humans is associated with the presence of an extra Y chromosome?
Klinefelter syndrome (47,XXY)
Explore the structure and function of the Y chromosome, including the pseudoautosomal regions (PARs) and the male-specific region of the Y (MSY). Learn about the homology with the X chromosome and the critical role of these regions in male gametogenesis.
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