Basic molecular and cell biology

1. CPY 804:
SINGLE NUCLEOTIDE
POLYMOPHISM

2. Introduction
Single Nucleotide Polymorphism
• Polymorphism is a generic term that means ‘many shapes’ i.e. the ability to
appear in different form.
• Single nucleotide polymorphisms or SNP (pronounced “snips”), are the
most common type of genetic variation among peoples.
• Each SNP represents a difference in a single DNA building block, called a
nucleotide.

3. Introduction cont’d
• SNP is defined as a single base change in DNA sequence that occurs
in a significant proportion (more than 1%) of a large population.
• In human, 99.9% bases are the same.
• Remaining 0.1% makes a person unique
• Different attributes
• Characteristics
• Traits
• How person looks
• Disease he/she develops

4. Introduction cont’d
• It is a DNA sequence variation
occurring when a single nucleotide A,
T, C, or G in the genome differs
between members of a species
• For example, two sequenced DNA
fragments from different individuals,
AAGCCTA to AAGCTTA, contain a
difference in a si ngle nucleotide

5. SNPs facts
• SNPs are found in
– coding and (mostly) non coding regions.
• Occur with a very high frequency
– about 1 in 1000 bases to 1 in 100 to 300 bases.
• The abundance of SNPs and the ease with which they can be measured make these
genetic variations significant.
• SNPs close to particular gene acts as a marker for that gene.
• SNPs in coding regions may alter the protein structure made by that coding region.

6. TYPES OF SNPs
Following are the types of SNPs
• Non-coding region
• Coding region
– Synonymous
– Non synonymous
• Missense
• Nonsense
• Methods of identification SNPs
• Detection of known SNPs
• Identification of new SNPs

7. Importance and application of SNPs
 SNPs is found
 Noncoding
 Intergenic
 Rare exons regions
 Presence of SNPs
 Harmless
• Change in phenotype
• Pigmentation
 Harmful
• Diabetes, cancer, heart disease
• Huntington’s and hemophilia
• Parkinson Alzheimer’s disease
 Researchers use SNPs in personalized medicine
individual’s response
Pharmacogenomics
Pharmacogenetics
 Tracking inheritance of disease genes within families
 Determine genotype and phenotypes in many
individuals
 Gene function identification
 Gene discovery and mapping