Question

A cell with a membrane-bound nucleus is known as

Answer 1

Hint: Cell structure varies according to the type of the cell. Prokaryotic cells and eukaryotic cells vary in many aspects. Prokaryotic cells lack a membrane-bound nucleus and cell organelles. Bacteria and mycoplasma are examples of prokaryotic cells. They multiply more rapidly than eukaryotic cells.

Complete answer:
Cells are of two types. They are prokaryotic cells and eukaryotic cells. Eukaryotic cells consist of a membrane-bound nucleus and cell organelles. Prokaryotes are unicellular organisms that lack a membrane-bound nucleus and cell organelles. The genetic material of prokaryotes is made up of DNA which is different from the eukaryotic DNA in its structure. Prokaryotic DNA is double-stranded and circular in structure. It is seen in a less organized structure present at the centre of the bacterial cell called the nucleoid. Unlike the nucleus present in eukaryotes, these are non-membrane bound structures that contain the circular, double-stranded DNA of prokaryotes. This DNA is smaller than eukaryotic DNA.
If the cell nucleus is covered by a distinctive membrane, these cells are called eukaryotic cells.
Other than chromosomal DNA, certain bacteria possess plasmid DNA which is an extrachromosomal DNA seen in bacterias. It can multiply independently and is small, circular, and double-stranded in structure. They contain only a limited number of genes. But they can introduce certain important characters to the bacteria.

Note: Plasmid DNA is important as it provides drug resistance to the bacteria in many cases. These plasmids can be transferred from one bacteria to the other and it causes the transfer of the drug-resistant genes to the whole bacterial colony. Plasmid DNA is used in genetic engineering techniques as vectors for gene transfer. We can link the desired gene sequence to a plasmid that replicates in the bacterial cell.