Question

I'm doing a biology project on DNA and I need a little help. Can you please explain methods of examining DNA and more information about genetic research?

Answer 1

DNA examination methods:

A. Physical map helps in determining the actual location of the gene on the chromosome, measured in terms of gene distance as base pairs. It may use molecular tags Expressed tag sequence (ETS) or radio-hybrids or radio isotopes of nucleotides., by:

a. Hybridization mapping (like FISH or fluorescent in situ hybridization)

b. Restriction mapping

c. STS or sequence tagged site mapping

B. Genetic mapping is based on using genetic techniques, to determine the genetic location, by using genetic markers like:

a. Restriction length polymorphism (RFLPs).

b. Simple sequence length polymorphism (SSLPs)- minisatellites or VNTRs (Variable numbers of tandem repeats), microsatellites or STRs (short tandem repeats).

c. Single nucleotide polymorphism (SNP).

Genetic research:

1. CRISPR-

• CRISPR is Clustered Regulatory Interspaced Short Palindromic Repeats.
• CRISPR associated –Protein 9 nuclease (Cas-9) is used as a molecular tool for editing of genomes.
• It acts in a similar manner as genetic engineering or construction of GMO (genetically modified organism).
• CRISPR/ Cas9 system has components that help in their gene editing:

1. crRNA- guide RNA (g RNA) and sequence recognizing tracrRNA
2. tracrRNA- in stem-loop structure, bind (to be activated) to cRNA
3. Cas9-active form have nuclease, nick formation, single strand/double strand breaks, editing.
4. sgRNA-single guide RNA-with combination of other components

• The components may be introduced within the organism through plasmid.
• The plasmid may be introduced by transfection or by direct injections into the target cells.
• Also some virus mediated vectors may be used or liposomes.
• For transgenic organism creation for mutational related studies like cancer mutations, knockout of the wild type genes is used.

2. Genetic testing-

A specific mutation in genes, chromosomes, or proteins; in form of changes during inheritance, may be neutral (with no effect), beneficial or harmful. These inherited changes, may be detected by genetic testing. Inherited alteration in a person’s genome may be potentially harmful, when they may be factor for diseases running in a family.

In such cases, genetic testing may be applied to detect DNA, RNA, or protein of an individual, to observe and analyse:

1. Genetic mutation

2. genotypes related to the disease

3. phenotypic alterations

4. karyotypes.

Example: Considering an autosomal dominant genetic disease, which is caused by mutation in a single copy of gene form a parent in a family. This disease is referred to as e FAD or early onset of Familial Alzheimer Disease.

If genetic testing is done (even when the individual is asymptomatic), it will help in detection of the presence of e FAD gene, how it may affect in near future, weather the defect will be present in the progeny.