DNA Ladders

DNA Ladders

• Hind III DNA marker

• PST I DNA marker

Bacteriophage lambda DNA was used. Molecular weight 48.5kb of genomic DNA. Hind III gaston was carried and then restriction with PST 1 was performed.

In both cases, different molecular weight fragments were formed which by running gel were used as markers. Later, more fine fragments came using her enzymes. Similarly, protein markers were formed by putting all proteins of different molecular weights in one tube. Likewise, markers forensics are finer.

The combined DNA Index System (CODIS) uses 13 STR sites. We can make our own markers by amplifying all 13 STR sites, running on el purifying them, and by comparing it with some marker as the molecular weight will be compared. So by putting them on gel.markers of known molecular weights. These can be used as DNA Ladder.

Much bands/markers that have up to 100-500 bp fragments are required. Not bigger fragments like 500 or above. The difference of 3-4 nucleotides can be seen with the help of these markers. For example, in the case of VIVA, if there is a mnge of -5-10 then fragments for 5,6,7,8,9,10 should come. Markers should be finer for it: there should be markers for all possible alleles.

Amelogenin is a site on the X chromosome, on the basis of which gender can be discriminated against. It also contributes to teeth enamel. There is a deletion of 6 bp on the X chromosome. e.g. y chromosome will give 112bp of amelogenin, in X the fragment will be of 100bp. Thus if in a sample two peaks are obtained then it belongs to a mole.

In a female sample, a single peak is obtained, product size or peak height will be more as it will be producing more. In the case of a sexual assault case, there will be mixed samples.

Through the ladder, size can be identified. There may be a problem. For example, as in the Indian population, there is a deletion in both or not in both. As a result, there will be one product; no differentiation.

As the y chromosome is different from x thus there might be some other site as well.

• In first-generation multiplex PCR, the SIR sites used have the power of discrimination 1 in 10,000. 4 SIR sites were used:

● TH01	● VWA
● FES/FPS	● F13A1

• Ability to identify 1 person out of 10,000.

Second generation Multiplier (SCOM):

• It was claimed to have the power of discrimination 1 in 50 million 6 SIR sites were used:

● TH01	● FGA	● D18S11
● VWA	● D8S1179	● D21S11

In use is the 13 CODIS System.

● D3S1358	● TPOX	● CSFIPO	● LPL
● F13B	● THOI	● F13A01	● FES/FPS
● FGA	● D5S818	● D7S820	● D8S1179
● D13S317	● D21S11	● D16S539	● D18S51

• The purpose is to reach the individual out of the population.

• New sites can also be used, some can be removed.

Editor's Recommendation:

• Analysing Metabolic Pathways
• Protein Threading Sequence
• Ab Initio Protein Structure Prediction
• Homology Modeling
• Hot Start PCR, Multiplex PCR, Avoiding Contamination In PCR, Advantages, and Disadvantages in PCR
• DNA Damage
• Docking | Protein-Protein Docking | Protein-Ligand Docking 
• Functional Regulation | Genetic Aspect | Indirect Aspects 
• Database Development 
• Functional Analysis At Structure Level
• PTMs and Functional Regulations
• Modeling Cellular Processes
• PCR Reagents | Stochastic Effect | STR Classification
• DNA Degradation
• DNA Quantification | Human DNA Quantification Method | Advantages  
• Desirable Characteristics of STR used in Forensic DNA typing
• Metabolic Pathways
• Non-Human DNA
• Mitochondrial DNA 
• Integrated Genomic Circuits 
• Shutter Product Formation 
• STR Sites
• Mini STR Sites 
• Molecular Diagnosis of Genetic Diseases
• Immuno Quantitative Assay
• Real-Time PCR