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प्रश्न
Write a note on Down’s syndrome.
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उत्तर
Down syndrome:
- Individuals suffering from Down syndrome will have 47 chromosomes instead of the normal number 46.
- 21st Trisomy occurs due to non-disjunction or failure of separation of chromosomes (autosomes) during gamete formation.
- Following are the symptoms of Down syndrome:
- Mild or moderate mental retardation and poor skeletal development.
- Distinct facial features like small head, ears, and mouth.
- The face is typically flat and rounded with a flat nose, open mouth, and protruding tongue.
- Eyes slant up and out with internal epicanthal folds.
- Flat hands and stubby fingers, the palm is broad with a single palmer crease.
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संबंधित प्रश्न
Give reasons for the development of Turner’s syndrome and also mention its symptoms.
Identify the characteristics that are observed in an individual suffering from Klinefelter syndrome.
i. Gynaecomastia, under developed testis and no spermatogenesis.
ii. Voice pitch is harsh.
iii. They are tall with long arms.
Match Column I with Column II and select the correct option:
| Column I | Column II | ||
| p. | Pleiotropy | I. | More than two alleles occur at the same locus on homologous chromosomes |
| q. | Multiple alleles | II. | Expression of both the alleles m heterozygous condition |
| r. | Polygenic | III. | Multiple effect of single gene |
| s. | Co-dominance | IV. | Single phenotypic character influenced by more than two genes |
Identify the option that correctly represents the number of chromosomes in Down syndrome.
The person with Turner’s syndrome has ______.
Down’s syndrome is due to ______.
The most striking example of point mutation is found in a disease called ______.
Read the following and answer from given below:
Turner's syndrome is an example of monosomy. It is formed by the union of an allosome-free egg and a normal 'X' containing sperm or a normal egg and an allosome-free sperm. The individual has 2n = 45 chromosomes (44 + X0) instead of 46. Such individuals are sterile females who have rudimentary ovaries, underdeveloped breasts, small uterus, short stature, webbed neck, and abnormal intelligence. They may not menstruate or ovulate. This disorder can be treated by giving female sex hormones to women from the age of puberty to make them develop breasts and have menstruation. This makes them feel more normal.
The number of Barr bodies present in a female with Turner's syndrome is ______
Read the following and answer from given below:
According to Mendel, one gene controls the expression of one character only. The ability of a gene to have multiple phenotypic effects because it influences a number of characters are an exception. The gene has multiple phenotypic effects because its ability to control two or more characters can be seen in cotton. In cotton, a gene for the lint also influences the height of the plant, size of the ball, number of ovules, and viability of seeds.
Which of the following disorder is an example of genes with multiple phenotypic effects?
Give definition of non-disjunction.
