Gene knockdown: Gene knockdown is an experimental technique by which the expression of one or more of an organism's genes are reduced. Gene expression is the process through which a gene is used to create a protein. Various processes, both natural and artificial, can interrupt this process. The reduction can occur either through genetic modification or by treatment with a reagent such as a short DNA or RNA oligonucleotide that has a sequence complementary to either gene or an mRNA transcript. This is not as dramatic as a gene knockout, and there may still be some expression of your gene. A variant of gene knockdown is known as gene silencing, in which gene expression is stopped without knocking out the gene.
Several methods have been employed to inactivate genes in cultured cells. Such as TALEN and the newly CRISPR, among the most accessible of these is the use of RNA interference (RNAi) to knock down gene expression. Compared with gene targeting by homologous recombination, RNAi-mediated gene knockdown is rapid, relatively inexpensive and thereby adaptable to high-throughput approaches. However, the results of RNAi can vary between experiments and between laboratories. In addition, RNAi can have off-target effects that can be difﬁcult to predict and interpret. For these reasons, RNAi is not generally as deﬁnitive nor as reproducible as the analysis of a genetically altered cell line.
Difference between gene knockout and knockdown: The difference between knockdown and knockout is that knockout is when you genetically modify cells or animals to stop them expressing a gene, which means the gene has been completely silenced. While knockdown is when you use some kind of RNA interference to reduce mRNA of a gene from being translated into protein that's the expression has been reduced but some protein is still made. Knock out of a gene will remove the protien coded for by that gene entirely, knockdown will reduce it by at least 70%. For gene knockout, there is no detectable gene expression, while in knockdown there is the reduction of gene expression.
Knockdown is (genetics) the use of a reagent such as an oligonucleotide with sequence complementary to an active gene or its mRNA transcript, to interfere with the expression of said gene while knockout is (genetics) designating an organism in which a particular gene has been removed or deactivated. On the other hand, as nouns the difference between knockdown and knockout is that knockdown is an act of knocking down or the condition of being knocked down while knockout is the act of making someone unconscious, or at least unable to come back on their feet within a certain period of time. As adjectives knockdown is powerful enough to overwhelm or knock down while knockout is rendering someone unconscious.
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