Question

State a method of cellular defense which works in all eukaryotic organisms.

Answer 1

A simple and fast method of silencing gene expression in a range of species is double-stranded RNA-mediated interference (RNAi). A gene silencing is a function of RNA degradation into short RNAs that activate ribonucleases to attack homologous mRNA.

Complete answer:
A gene silencing is a function of RNA degradation into short RNAs that activate ribonucleases to attack homologous mRNA. The resulting phenotypes are either similar to genetic null mutants or mimic a sequence of mutants in an allelic form. Two ancient processes, cosuppression in plants and quelling in fungi, have been shown to be linked to complex gene silencing, and regulatory processes such as transposon silencing, antiviral defence mechanisms, gene regulation, and chromosomal alteration have also been connected. Protection of the genome against invasion by mobile genetic elements such as viruses and transposons and coordinated functioning of eukaryotic organisms' developmental programmes tend to be the normal functions of RNAi and its associated processes.
The defence mechanism that is prevalent in all eukaryotes is the interference of RNAi or RNA. A significant pathway that is used for controlling gene expression in many different species is RNA interference (RNAi). To identify a cellular mechanism that uses the gene's own DNA sequence of a gene to turn it off, the term RNA interference (RNAi) was coined, a process that researchers call silencing. RNAi is caused by double-stranded RNA (dsRNA) in a large range of species, including mammals, plants, and fungi. In order to learn more about their work, RNAi is commonly used by researchers to silence genes. SiRNAs can be designed to fit any gene, can be generated inexpensively, and can be administered to cells easily.

Note: Analyses of these mutants contributed to the discovery of host-encoded proteins involved in the silencing of genes and also revealed that these processes are common to a number of important enzymes or factors. Some of the identified components act as initiators, while others act as gene silencing process effectors, amplifiers and transmitters.