DNA ladder is commonly used to determine the size of DNA fragments by electrophoresis in routine molecular biology laboratories.

When run alongside an unknown PCR product in an agarose gel, the ladder allows you to estimate the size of the unknown fragment by comparing it to the closest band in the ladder lane, like so: Ladder is also run alongside RFLP products to help estimate the size of the restriction fragments.

A DNA marker (also known as a size standard or a DNA ladder) is loaded into the first well of the gel. The fragments in the marker are of a known length so can be used to help approximate the size of the fragments in the samples. The prepared DNA samples are then pipetted into the remaining wells of the gel.

The DNA ladder is a standard sized fragment of DNA used to determine the molecular weight of the PCR amplicons. Broadly, it is categorised into the standard molecular weight size marker. DNA ladder, RNA ladder and protein ladder are used for the sizing of DNA, RNA and protein respectively.

DNA marker means a sequence of DNA used to mark a particular location on a particular chromosome while DNA ladder is just DNA fragment of specific size and it could be from any source of DNA .

Standard DNA markers are generated by restriction digestion of plasmid and deproteinization of the DNA fragments. The molecular weight of the digested DNA fragments determines the distance they would migrate on the gel.

a DNA fragment or mixture of fragments of known size subjected to gel electrophoresis along with unknown DNA samples to enable preparation of a standard curve for estimation of the sizes of unknown fragments. Return to Search Page.

Determining the size of DNA or RNA in nucleic acid electrophoresis is accomplished by comparison to size standards, also called markers or ladders. Typical size standards are made up of DNA or RNA fragments in variable length in the range of 10bp to 1000bp (base pair) increments.

These DNA size standards can be used as positive controls for electrophoresis and for determining the sizes of unknown DNA fragments.

Description: MCLAB’s DNA Size Standard series products are internal lane standards that are intended to be used in assigning sizes to DNA fragments on fluorescence-detecting instruments. Common applications include genotyping and DNA Fragment Analysis.

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