Download Frequently Asked Questions (FAQ`s) Q1. What are chromosomes

Frequently Asked Questions (FAQ’s)
Q1. What are chromosomes?
Ans: Chromosomes are the vehicles by which hereditary
information is physically transmitted from one generation to
the next; in a bacterium, the chromosome consists of a
single nacked circle of DNA; in eukaryotes, each chromosome
consists of a single linear DNA molecule and associated
proteins.
Q2. What are autosomes?
Ans: The chromosomes which have no relation with the sex
and contain the genes which determine the somatic
characters of the individuals are known as autosomes.
Q3. What are sex chromosomes?
Ans: The chromosomes which are responsible for the
determination of sex are known as sex chromosomes, e.g., X
and Y chromosomes
Q4. What is karyotype?
Ans: The karyotype is the whole group of characteristics that
allows the identification of a particular chromosomal set. It is
characteristic of an individual, species, genus, or larger
grouping, and may be represented by a diagram called
karyogram or ideogram.
Q5. What is dosage compensation?
Ans: A phenomenon in which the activity of a gene is
increased or decreased according to the number of
copies of that gene in the cell.
Q6. What are barr bodies?
Ans: A condensed mass of chromatin found in the nuclei of
placental mammals that contain one or more X
chromosomes. Named for its discoverer, Murray Barr.
Q7. What is the significance of sex chromosomes?
Ans: Sex chromosomes play a unique role in many biological
processes and phenomena, including sex determination,
epigenetic gene expression, the distribution of genes in the
genome, genomic conflict, local adaptation, and speciation.
Q8. What is sex determination?
Ans: It is the phenomenon wherein the sex of an individual
organism becomes fixed soon after the formation of a zygote,
due to the specific composition of sex chromosomes.
Q9. What is Klinefelter's syndrome?
Ans: Klinefelter's syndrome is caused by the presence of one
or more extra copies of the X chromosome in a male's cells.
Q10. What are the symptoms of Klinefelter's syndrome?
Ans: The extra genetic material may lead to tall stature,
learning and reading disabilities, and other medical problems.
When additional X and/or Y chromosomes are present in
48,XXXY, 48,XXYY, or 49,XXXXY, developmental delays and
cognitive difficulties can be more severe and mild intellectual
disability may be present.
Q11. What is Turner syndrome
Ans: This is the condition where each of a female has one
normal X chromosome and the other sex chromosome is
missing or altered.
Q12. What is homomorphic and heteromorphic?
Ans:
A
pair
of
chromosome
which
looks
identical
in
appearance is called homomorphic and the chromosome pair
different in appearance from each other is known as
heteromorphic.
Q13. What is the structure of X and Y chromosome?
Ans: The X chromosomes of most organisms are straight,
rod-like and comparatively larger than Y chromosomes. The
Y chromosome is smaller in size, with one end slightly curved
or bent to one side in Drosophila; in man and Melandrium no
such curvature of Y chromosome occurs.
Q14. What is Lyon hypothesis?
Ans: The Lyon hypothesis suggests that in the XX female,
one X chromosome is genetically inactive after a certain
stage in embryogenesis; that this 'inactive' X chromosome
forms the Barr body, which can be identified at about the
sixteenth day in the human embryo.