What is the Difference Between Gene Knockout and Knockdown?

The main difference between gene knockout and knockdown lies in the extent of gene inactivation:

• Gene Knockout: This involves the complete elimination of a gene from an organism, making the gene inoperative. Gene knockout can be achieved through genetic engineering techniques such as homologous recombination, zinc fingers, TALENs (Transcription activator-like effector nucleases), and CRISPR/Cas9. Organisms with knocked-out genes are called knockout organisms or knockouts (KO).
• Gene Knockdown: This refers to the reduction of the expression of a gene in an organism, rather than complete elimination. Gene knockdown can occur through chemical agents or genetic modification. The process involves the binding of an oligonucleotide, which can block transcription, degrade the mRNA transcript, destroy pre-splicing sites, or block the translation process. Gene knockdown is often achieved using interference RNA.

Both gene knockout and knockdown are used to study gene function and the effects of gene loss or reduction on an organism's functioning. However, gene knockout completely silences the gene, while gene knockdown only reduces its expression, still allowing for some protein production.

Comparative Table: Gene Knockout vs Knockdown

Here is a table comparing gene knockout and gene knockdown:

In summary, gene knockout involves the complete erasing or inactivation of target genes, resulting in no gene expression. On the other hand, gene knockdown refers to a reduction in mRNA expression of a gene, but some protein is still produced. Different methods are used to achieve these results, such as CRISPR/Cas9 for gene knockouts and RNA interference (RNAi) for gene knockdowns.