Question

Discuss with your teacher and find out how to distinguish between
A. Plasmid DNA and chromosomal DNA
B. RNA and DNA
C. Exonuclease and endonuclease

Answer 1

DNA is the genetic material of all living organisms. It is found in the form of chromatin or chromosome. DNA has information for the characteristics of organisms. Plasmid DNA is extrachromosomal DNA. DNA and RNA are polynucleotides. These are the polymers of nucleotides. A nucleotide is made by sugar, n-base, and a phosphate group. Nuclease enzymes are the enzymes that cleave the DNA molecule. There are two types of nuclease enzymes are exonuclease and endonuclease.

Complete answer:
A. Chromosomal DNA is the main genetic material of every living organism only except some plant viruses. The plasmid is the extrachromosomal DNA and it is only found in some bacteria and in Yeast. Chromosomal DNA is self-replicating but plasmid DNA sometimes depends on the main chromosomal DNA for replication. Chromosomal DNA has all genes that synthesize such enzymes that are required for the completion of biological processes like respiration and photosynthesis. Plasmid DNA lacks such important genes. A plasmid is just an associative and dispensable structure. Plasmid DNA has some genes that are responsible for the special character of bacteria like resistance towards any toxin and heavy metals.
B. RNA is the genetic material of only some plant viruses while DNA is the genetic material of all organisms. In all organisms, RNA has a structural and adaptor role. DNA has de-oxy ribose sugar while RNA has ribose sugar. DNA has adenine, guanine, cytosine, and thymine as N-base. RNA has Uracil instead of thymine. DNA is more stable than RNA. RNA is single-stranded but DNA is double-stranded. Nuclease enzymes break the DNA at the phospho-diester bonds.
C. Exonuclease enzymes remove nucleotides from ends of the DNA but endonuclease enzymes break internal phospho-diester bonds of DNA and cut the mid part of DNA but don’t remove the end part.

Note: Restriction endonuclease enzymes are special endonuclease enzymes that cut the DNA after recognizing the specific nucleotide base sequence that is known as the restriction site.