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प्रश्न
Explain the structure of chromosomes with labelled diagram.
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उत्तर
Structure of chromosome:
- A typical chromosome consists of two chromatids joined together at the centromere also known as primary constriction.
- Primary constriction consists of a disk shape plate called the kinetochore. During cell division, spindle fibers get attached to the kinetochore.
- Apart from primary constriction, a few chromosomes possess an additional one or two constrictions called secondary constriction.
- At secondary constriction I (nucleolar organizer), nucleolus becomes organized during interphase.
- A satellite body (SAT body) is attached at secondary constriction II, in very few chromosomes.
- Each chromatid in turn contains a long, unbranched, slender, highly coiled double-stranded DNA thread, called chromonema, extending through the length of the chromatid.
- The ends of chromosomes (i.e. chromatids) are known as telomeres.
A: Parts of chromosomes
B: Showing secondary constrictions and details
Structure of Chromosome
संबंधित प्रश्न
Enumerate the various changes that occur in the nucleus of the cell during anaphase of mitotic division.
(i) Draw a neat labeled diagram to show the metaphase stage of mitosis in an animal cell having ‘6’ chromosome.
(ii) How many daughter cells are formed at the end of mitosis and at the end of meiosis?
(iii) With reference to cell division explain the following terms:
(Chromatid, Centromere, Haploid).
(iv) Name the type of cell division that occurs during:
1. Growth of shoot 2. Formation of pollen grains.
3. Repair of worn out tissues.
Complete the following sentence with appropriate word :
Polytene chromosomes are found in _________ of fly larvae.
State the Location: Chromosomes
What' does 'P' and 'Q' represent in the following diagram of X and Y chromosomes? Select the correct option representing, its appropriate description.
Identify the TRUE statements with respect to aneuploidy.
- When the chromosome number is not the exact multiple of the haploid set, it is described as aneuploidy.
- Aneuploidy is only addition of one or more chromosome(s) to the total number of chromosomes in a cell.
- Aneuploidy is further classified as hypoploidy and hyperploidy.
Differentiate between X-chromosome and Y-chromosome with reference to –
- length of non-homologous regions
- type as per the position of the centromere
The female gamete/egg cell of a human cell will have ______.
Which of the following describes the correct type of chromosome?
X- chromosome: A : : Y-chromosome: В
