DNA As The Defining Molecule of Life
- In eukaryotes, DNA is packed inside the nucleus as chromosomes.
- Smaller, separate DNA molecules also exist in mitochondria (mtDNA) and, in plants and algae, in chloroplasts (cpDNA).
Definition
DNA (Deoxyribonucleic Acid)
A double-stranded molecule that stores and transmits genetic information in living organisms.
RNA As The Working Copy of Genetic Information
Definition
RNA (Ribonucleic Acid)
RNA is a single-stranded nucleic acid that plays a key role in coding, decoding, regulation, and expression of genetic information.
- RNA is found in both the nucleus and cytoplasm, acting as the link between genetic information and protein synthesis.
- Its key forms and functions are:
- mRNA: carries genetic code from DNA to ribosomes.
- tRNA: delivers amino acids to the ribosome.
- rRNA: forms part of ribosomes and catalyses peptide bond formation.
DNA stores genetic information permanently; RNA is used for short-term communication and protein production.
RNA as Genetic Material in Viruses
- Some viruses contain RNA instead of DNA as their genetic material.
- Their RNA carries the information needed to make viral proteins, but replication only occurs inside a host cell.
- Coronavirus (SARS-CoV-2): single-stranded RNA genome.
- HIV: retrovirus that converts RNA to DNA inside host cells.
- Influenza virus: RNA genome divided into segments.
