Lab protocols
Well-established core methods as step-by-step checklists. In each protocol's "Variable explorer" you can change conditions such as gel %, antibody dilution, template amount or split ratio and compare two settings side by side.
Protein
Separating, quantifying and detecting proteins
Western blot SDS-PAGE → transfer → detectionSeparate proteins by size (SDS-PAGE), move them onto a membrane (transfer) and find one protein with antibodies. The skeleton rarely changes, but gel %, loading amount, antibody dilution and transfer conditions are adjusted for every experiment — use the "Variable explorer" below to see what each change does.⏱ 1.5–2 days🔬 variables 7 · simulators 5 · comparisons 2BCA protein assayProteins reduce copper ions and BCA turns purple in proportion. A standard curve from known concentrations (BSA) converts each sample's absorbance into a concentration.⏱ 45–60 min🔬 variables 4 · simulators 1 · comparisons 1Sandwich ELISAThe target is sandwiched between a plate-bound capture antibody and a detection antibody, then quantified by an enzyme colour reaction. The standard curve is S-shaped, so diluting samples into its middle is the key step.⏱ 4–5 h (kit) · 1–2 days with coating🔬 variables 5 · simulators 1 · comparisons 1
Nucleic acids · PCR
From RNA extraction to cDNA and qPCR
RNA extraction phenol–guanidine methodCells are lysed in a phenol–guanidine reagent; adding chloroform splits the mixture into layers and RNA stays in the clear upper aqueous phase. It is then precipitated with isopropanol. Preventing RNase and not disturbing the layers is everything.⏱ About 1.5 h🔬 variables 5 · simulators 1 · comparisons 1cDNA synthesis reverse transcriptionReverse transcriptase converts RNA into DNA (cDNA). For fair qPCR comparisons every sample must be converted under identical conditions — the same RNA amount and the same master mix.⏱ About 1 h🔬 variables 4 · simulators 0 · comparisons 1SYBR Green qPCRSYBR dye fluorescence rises as DNA doubles each cycle; the cycle where it crosses a threshold (Ct) compares starting amounts. Halving the template delays Ct by about one cycle.⏱ About 2 h🔬 variables 5 · simulators 2 · comparisons 0
Cell culture & assays
Growing and storing cells, and cell-based assays
Passaging adherent cellsWhen a vessel fills up, detach the cells and move a fraction into a new vessel. The split ratio sets when you will split next, and trypsin exposure affects cell health.⏱ 20–30 min🔬 variables 4 · simulators 1 · comparisons 0Freezing and thawing cellsThe rule is "freeze slowly, thaw quickly". DMSO prevents ice crystals but is itself toxic, so dilute it away immediately after thawing.⏱ Freeze 30 min + overnight · thaw 15 min🔬 variables 5 · simulators 0 · comparisons 1MTT / CCK-8 cell viabilityMetabolically active cells convert a reagent into a coloured product; its absorbance compares viability. The key is choosing cell number and incubation so the control is neither too faint nor saturated.⏱ 3–4 days (1–2 h hands-on)🔬 variables 5 · simulators 1 · comparisons 1Immunofluorescence stainingFix cells, permeabilise membranes and detect the target with fluorescent antibodies. The right fixation and permeabilisation depend on the target, so compare two methods side by side at first.⏱ 1–2 days🔬 variables 5 · simulators 1 · comparisons 1
Always follow reagent, kit and antibody manuals and your institution's safety rules first.