Question

Lampbrush chromosome contain
a. One chromatid
b. Two chromatids
c. Three chromatids
d. Several chromatids

Answer 1

Hint: They are chromosomes found mostly in animals but not in mammals. They are highly used in resolution of mapping of DNA sequences and construction of cytological maps for single chromosomes. Lampbrush chromosomes contain two chromatids. Chromosomes transform into the Lampbrush during the Stage of dilute, meiotic prophase due to an active transcription of many genes. They are highly extended to meiotic half-bivalents, each consisting of 2 sister chromatids.

Complete answer:
> One chromatid: A single chromatid is identical to a replicated chromosome. At the time when cells are divided, chromosomes first replicate to make sure that all the daughter cells receive a set of chromosomes.

> Two chromatids: In case of the same sister chromatid, single or double chromatids are of the same chromosome which are put together by a single centromere. A pair is called dyad. When they are separated, they turn into chromosomes again.

> Three chromatids: A chromosome consists of two identical halves of a replicate chromatid. There are no more chromatids in a chromosome so it is clear that this statement is incorrect.

> Several chromatids: As explained above in the answer. A chromosome is made up of two chromatids now also called sister chromatids. This statement does not fit into the information gathered.

Hence, The correct answer is option (B).

Note: Lampbrush consists of two chromatids which are also called sister chromatids. They are mainly found in growing eggs of animals but it does not include mammals in them. They transfer into Lampbrush at the stage of dilute.