Molecular Weight Markers
Molecular Weight Markers - Related Videos
09:30
Extraction of High Molecular Weight DNA from Microbial Mats
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Cited by 4 •
2011
We provide an improved protocol for extracting high molecular weight DNA from hypersaline microbial mats. Microbial cells are separated from the mat matrix prior to DNA extraction and purification. This enhances the concentrations, quality, and size of the DNA. The protocol may be used for other refractory samples.
01:01
Polymers: Defining Molecular Weight
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2023
Unlike small molecules with definite molecular weights, polymers are a mixture of individual polymer chains of varying lengths, each with a unique molecular weight. So, the molecular weight of a polymer is expressed as an average value based on the average size of the polymer chains. The two most common forms of averages used for polymers are the number average molecular weight and weight average molecular weight. The number average molecular weight (Mn) is the summation of the number...
01:10
Polymers: Molecular Weight Distribution
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2023
For any given polymer, the weight average molecular weight (Mw) is higher than, if not equal to, the number average molecular weight (Mn). The only situation in which the weight average molecular weight and the number average molecular weight are equal is when a polymer consists only of chains with equal molecular weight. However, this never happens in a synthetic polymer, since it is difficult to control the polymerization process up to a molecular level with accuracy to a hundred percent.
13:00
Low Molecular Weight Protein Enrichment on Mesoporous Silica Thin Films for Biomarker Discovery
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Cited by 11 •
2012
We developed a technology based on mesoporous silica thin film for the selective recovery of low molecular weight proteins and peptides from human serum. The physico-chemical properties of our mesoporous chips were finely tuned to provide substantial control in peptide enrichment and consequently profile the serum proteome for diagnostic purposes.
11:24
Extraction of High Molecular Weight Genomic DNA from Soils and Sediments
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Cited by 21 •
2009
A methodology to isolate high molecular weight and high quality genomic DNA from soil microbial community is described.
FAQs
Matching the conditions makes the marker bands a meaningful reference for sample migration. Gel type, separation context, and the effects of molecular size and electrical charge determine how components move. Comparing bands produced in the same run therefore supports a more consistent estimate of an unknown sample’s molecular weight than comparing results from different conditions.
Protein ladders are paired with SDS-PAGE, whereas DNA or RNA ladders support nucleic acid separation through agarose or polyacrylamide gels. This distinction matters because the marker must match the class of molecule and the separation system being analyzed. Selecting the corresponding ladder lets researchers compare protein bands with protein standards or nucleic acid bands with nucleic acid standards.
Marker components do not migrate randomly: their movement through the gel reflects properties such as molecular size and electrical charge. Those differences produce discrete bands at positions that can serve as reference points. A sample band is interpreted by comparing its position with nearby marker bands, allowing an estimate of molecular weight within the separation context.
Comparison with the reference bands can support several decisions at once: estimating the unknown molecular weight, checking whether a product appears at the expected position, assessing sample integrity, and monitoring purification. The marker does not replace the sample result; instead, it provides the positional standard needed to interpret those observations within the gel.
Selection follows the molecule and gel system: use a protein ladder for SDS-PAGE, and choose a DNA or RNA ladder for nucleic acid separation through agarose or polyacrylamide gels. Matching these elements prevents comparisons across incompatible standards and makes the resulting bands more useful for estimating molecular weight and evaluating the sample.
Run the selected marker alongside the unknown biological sample under the same gel electrophoresis conditions. After separation, locate the marker’s discrete bands and compare the sample bands with them. This comparison provides a molecular-weight estimate and can also help determine whether an expected product is present or whether sample integrity and purification should be examined.
They are useful when researchers need a size reference during molecular analysis, including sample characterization, product verification, integrity assessment, and purification monitoring. Their role extends across molecular biology, genetics, and biotechnology because the same comparison principle helps interpret proteins as well as DNA or RNA, provided the appropriate ladder and gel system are used.