Question

During what genetic process are lampbrush chromosomes present in vertebrates?

Short answer

Answer: Lampbrush chromosomes are present in vertebrates during the genetic process of oogenesis, specifically in primary oocytes at the diplotene stage of the first meiotic division (prophase I).

Step-by-step solution

Definition of Lampbrush Chromosomes

Lampbrush chromosomes are a special type of chromosome found in certain cells of vertebrates during a particular stage of cell division. They are named after their unique appearance, which resembles a lampbrush or a feather duster due to their extended lateral loops.

Function of Lampbrush Chromosomes

The function of lampbrush chromosomes is to hold extended regions of DNA that facilitate the high levels of transcription (making RNA from the DNA) necessary during a certain phase of cell division. These transcriptionally active regions are densely packed with RNA molecules and proteins essential for the cell's development during this stage.

Genetic Process Involving Lampbrush Chromosomes

Lampbrush chromosomes are present during the genetic process called oogenesis (the formation and development of egg cells or oocytes) in vertebrates. More specifically, they are found in primary oocytes during the diplotene stage of the first meiotic division (prophase I). The large loops of decondensed chromatin in lampbrush chromosomes play a key role in producing ribosomal RNA and other transcripts required for the proper development of the egg cell before fertilization.

Conclusion

In summary, lampbrush chromosomes are present in vertebrates during the genetic process of oogenesis, specifically in primary oocytes at the diplotene stage of the first meiotic division (prophase I). Their unique structure plays a crucial role in facilitating transcription and the production of essential RNA molecules needed for egg cell development.