Question

During DNA replication in prokaryotes, DNA is attached to
(a) Chromosome
(b) Mesosome
(c) Nucleus
(d) Ribosome

Answer 1

These are also called chondroid and are folded invaginations in the plasma membrane of bacteria or prokaryotes that are being produced by the chemical fixation techniques for preparing samples for electron microscopy.

Correct step by step answer:
The DNA is attached to mesosomes during DNA replication in prokaryotes. Mesosomes may be a convoluted membranous structure formed during the invagination of the cell wall of a prokaryotic cell. The process by which two identical replicas of DNA are produced from the original DNA is called DNA replication.

Additional Information:
- Replication of DNA in prokaryotes starts from a sequence found on the chromosome called the origin of replication.
- At this point the enzyme helicase exposes the DNA helix, leading to the formation of the replication fork. Single- strand binding proteins bind to the single- stranded DNA near the replication fork to stay the fork open.
- The enzyme primase synthesizes an RNA primer to initiate synthesis by DNA polymerase, which may add nucleotides only within the 5' to 3' direction.
- Within the direction of the replication fork one strand is synthesized continuously, this strand is called the leading strand.
- The other strand is synthesized during a direction far away from the replication fork. This strand is known as the lagging strand.
- The RNA primers are replaced by DNA nucleotides once replication is completed, and therefore the DNA is sealed with DNA ligase, which creates phosphodiester bonds between the 3'hydroxide of one end and therefore the 5' phosphate of the opposite strand.
- The functions of mesosomes are as follows :
- These mesosomes help within the synthesis of the cell membrane and replication of DNA. They also help within the equal distribution of chromosomes into the daughter cells.
- Mesosomes also increase the area of the cell wall to hold out various enzymatic activities.
- They help in both secretion processes as well as in bacterial respiration.
So, the correct answer is,’ Mesosome’.

Note:
- The bacteria show special invagination of the plasma membrane, termed as mesosomes.
- They are believed to serve as anchor points for the attachment of the daughter strand.
- Through the mesosome, DNA in the cell is attached to the cell membrane, and the remains attached during cell division.