Question

How does SNP profiling differ from STR profiling? Drag the appropriate items to their respective bins. Reset Help amplifies target regions of the sample by PCR uses repeated sequences detects alleles by the different sizes of the amplified products uses single-nucleotide polymorphisms detects alleles by hybridization to allele-specific probes or by sequence analysis SNP profiling STR profiling Both SNP and STR profiling

Answer 1

DNA profiling: 99% of nucleotide bases are same in all individual, DNA profiling are methods used to identify individual genetic makeup which makes one different from other.

This can be achieved by many methods but most recently developed among them are SNP ( single nucleotide polymorphism) and STR ( short tandem repeats)   

SNP profiling	STR profiling	Both SNP&STR profiling
Use single nucleotide polymorphism	Use repeated sequences
Detects allele by hybridization into allele specific probes or by sequence analysis	Amplifies target region of a sample by PCR

SNP

• otherwise called snips
• In SNP single nucleotide or base pair is varied in DNA among individual, profiling is done based on this variation.
• single small change in the Sequence because of mutation.
• most common type of genetic variation among people
• found in non coding regions most abundantly than coding regions
• Known as polymorphism due to high frequency in population
• SNPs close to particular gene acts as the marker
• can be used to get more comprehensive genetic picture than STR.

STR

• Small sections of non coding DNA repeating a number of times. A sequence is repeated
• Repeats can be from three times to fifty times, different in individuals
• STR occurs at a number of known sites and thus can be used to compare between people
• can be used to compare relationship between people, to solve paternity cases.
• SNPs can be interrogated by hybridizing complementry DNA probe to the SNP site.

Steps in STR DNA profiling

DNA obtained from target cell of individual

amplified using PCR ( polymeramised chain reaction)

DNA fragments are cut using Restriction enzyme at specific sequence

Cut fragments separated on basis of size using Gel electrophoresis

DNA injected into wells and electric current applied along gel

Since DNA negatively charged they move towards the positive side of gel

Small cut fragments move more faster towards the positive side

Fragments get separated on basis of size

Fluorescent image obtained by adding radioactive material to fragments.

Pattern of fragment distribution analyzed.

Steps in SNP

DNA extraction

DNA fragmentation

Sequencing

Mapping

SNP calling using mapped DNA