Deoxyribonucleic Acid (DNA) AND Ribonucleic Acid (RNA)

Why in news?

Increasing variants of the covid-19 virus and their consequences on humans.

Genetic carrier -Deoxyribonucleic acid (DNA) is the molecule that carries genetic information for the development and functioning of an organism.
Two strands -DNA is made of two linked strands that wind around each other to resemble a twisted ladder a shape known as a double helix.
- Each strand has a backbone made of alternating sugar (deoxyribose) and phosphate groups
The two strands are connected by chemical bonds called bases.
Four bases -Adenine (A), cytosine (C), guanine (G) or thymine (T).
Proofreading -The enzymes responsible for copying DNA, collectively known as DNA polymerases, possess error-correction property, known as ‘proofreading’.

dna_rna

Ribonucleic acid (RNA) is a nucleic acid present in all living cells that has structural similarities to DNA
RNA is most often single-stranded
An RNA molecule has a backbone made of alternating phosphate groups and the sugar ribose
Attached to each sugar is one of four bases: adenine (A), uracil (U), cytosine (C) or guanine (G)
Different types of RNA in cells are messenger RNA (mRNA), ribosomal RNA (rRNA) and transfer RNA (tRNA).
Some RNAs are involved in regulating gene expression.
RNA polymerases do not possess the ability to proofread

DNA Virus	RNA Virus
The DNA virus include the members of the pox family (smallpox and chickenpox) and Hepatitis B.	The RNA virus include COVID-19, AIDS, polio, influenza, dengue, chikungunya, Ebola, Zika.
DNA viruses contain DNA as their genetic material	RNA viruses contain RNA as their genetic material
Double-stranded DNA viruses are more common than single-stranded DNA viruses	Single-stranded RNA viruses are more common than double-stranded RNA viruses.
Viral DNA is replicated inside the nucleus of the host cell	Viral RNA is first transcribed and then is replicated in the cytoplasm
DNA viruses are stable due to the lower mutation rate.	RNA viruses are unstable due to the higher mutation rate
DNA viruses shows an accurate replication.	RNA viruses shows an error-prone replication

Survival advantage -Few odd variants possesses a survival advantage against a vaccine or a drug.
Such variants will undergo further natural selection and the virus will continue to proliferate.
Short generation time - In a very short period after infection the host’s virus population becomes enormous.
Affects immune system -High viral output together with the diversity overwhelms the immune system.
Zoonosis –The viruses can jump across species resulting in zoonosis.
Spread easily among newer hosts -Because the high error rate and the short generation time enable the virus to adapt to newer conditions much faster.

A zoonosis (zoonotic disease) is an infectious disease that is transmitted between species from animals to humans (or from humans to animals).

References