Is polytene chromosome present in oocytes of amphibians?


What are oocytes of amphibians?

Although the amphibian oocyte possesses a vast store of structural and regulatory components, the oocyte itself is extremely repressed in terms of its rate of protein synthesis. It can remain in this repressed state for a period of months or years, as it grows in the ovary by virtue of deposition of yolk platelets.

What is a polytene chromosome?

Polytene chromosomes develop from the chromosomes of diploid nuclei by successive duplication of each chromosomal element (chromatid) without their segregation. The newly formed chromatids remain associated lengthwise and together form a cable-like structure, referred to as polytene chromosomes.

What are Polytene and lampbrush chromosomes?

The main difference between polytene and lampbrush chromosome is that polytene chromosomes occur in the salivary glands and other tissues of insects whereas lampbrush chromosomes occur in the oocytes of vertebrates except for mammals and some invertebrates.

Which chromosome is Telocentric within a polytene chromosome?

They show somatic synapsis. The centromeres of all 8 chromosomes (2n=8) are together in a structure called the chromocenter, therefore they appear to have 5 long arms and one short one (chromosome 1 is the X and is telocentric, chromosome 2 and 3 are metacentric, and chromosome 4 is tiny and is telocentric).

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How does a polytene chromosome differ from a typical eukaryotic chromosome?

How does a polytene chromosome differ from a typical eukaryotic chromosome? … A polytene chromosome contains banding patterns and is large because of repeated replications of DNA without nuclear division. Although mutations have been observed in many different genes, they have not been isolated in histones.

Do polytene chromosomes show somatic pairing?

In salivary gland chromosomes/polytene chromosomes, pairing is formed between homologous chromosomes. A characteristics feature of these chromosomes is that somatic pairing occurs in them and hence their number appears half of normal somatic cells.

What is polytene chromosome write the procedure of squash preparation of Drosophila larvae for polytene chromosome?

4. Polytene chromosome squash preparation:

  1. Rinse larvae with water and transfer to PBS in a tissue culture dish for dissection.
  2. Grasp the tip of the mouth hooks with one pair of forceps, hold the body about 2/3 of the way down with the other pair, and pull on the mouth hooks so the salivary glands are exposed.