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Questions
Identify chromosomal disorder caused due to non-disjunction of the 21st number of chromosomes and enlist its symptoms.
Identify chromosomal disorder caused due to non-disjunction of 21% chromosome and enlist its characteristics.
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Solution
Down syndrome is usually caused by an error in cell division called non-disjunction. Non-disjunction results in an embryo with three copies of chromosome 21 instead of the usual two.
Common Symptoms (Characteristics) of Down syndrome are:
- Mild or moderate mental retardation and poor skeletal development.
- Distinct facial features like small head, ears and mouth.
- Eyes slant up and out with internal epicanthal folds.
RELATED QUESTIONS
Give the importance of heterocyst in cyanobateria.
Give a detail account of thalassemia.
Give an account of one Mendelian and one chromosomal disorder you have studied.
Read the following statements and select the correct option.
i. Genetic disorders are broadly categorised as, Mendelian disorders and chromosomal disorders.
ii. Mendelian disorders are caused due to absence or excess of one or more chromosomes or their abnormal arrangement.
iii. Chromosomal disorders are mainly caused due to alteration or mutation in the gene.
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.
A short stature with webbing of neck and low posterior hairline indicates ______ syndrome.
Extra chromosome ‘X’ is present in which one of the following cases?
Klinefelters’ syndrome is characterised by a karyotype of ______.
In Down's syndrome, karyotyping has shown that the disorder is associated with trisomy of chromosome number 21 usually due to ______.
