Quantitative PCR, also known as real-time PCR, is a molecular biology technique used to quantitatively measure the amount of a specific DNA sequence in a sample. It involves amplifying the DNA sequence of interest using PCR, and then measuring the amount of amplification product in real-time using fluorescent probes or dyes.
ΔΔCt, or delta delta Ct, is a calculation method used in qPCR to determine the relative change in gene expression between two different samples. It involves normalizing the quantification cycle (Ct) values of the gene of interest to an internal control gene, and then comparing the normalized values between the two samples to determine the fold change in gene expression.
ΔΔCt is calculated by first subtracting the Ct value of the internal control gene from the Ct value of the gene of interest for each sample, resulting in ΔCt values. The ΔCt values of the two samples are then subtracted from each other to obtain the ΔΔCt value. This value is then used to calculate the fold change in gene expression using the formula 2^-ΔΔCt.
ΔΔCt is a widely used method in qPCR because it allows for relative quantification of gene expression between two different samples without the need for an absolute quantification standard. It also accounts for variations in sample preparation and amplification efficiency, making it a more accurate way to compare gene expression levels.
While ΔΔCt is a useful method for relative quantification, it is important to note that it does not provide absolute quantification of gene expression. Additionally, it assumes that the amplification efficiency of the gene of interest and the internal control gene are equal, which may not always be the case. Careful experimental design and proper validation are important to ensure accurate results when using ΔΔCt in qPCR.