Presentation on marker genes
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Marker genes are DNA sequences with known chromosomal locations used in molecular biology to determine successful DNA insertion. They can be classified into selectable markers, like antibiotic resistance genes, and reporter markers, like green fluorescent protein, that help tag other genes. Selectable markers allow identification of transformed cells, while reporter markers measure gene expression and provide visual confirmation of transformation.
Presentation on marker genes
- 1. Marker Genes Tasmina Ferdous Susmi Jessore University of Science and Technology, Bangladesh
- 2. Marker gene Used in molecular biology. It is a DNA sequence with a known location on a chromosome. Used to determine if a piece of DNA has been successfully inserted into the host organism.
- 3. Characters of Marker Gene • Represent genetic differences between individual organisms or species. • Do not represent the target gene themselves but act as signs or flag. • Do not affect the phenotype of the desired genes. • Occupy specific genomic positions within chromosomes.
- 4. Types of marker genes Marker Selectable Marker Antibiotic Marker Non Antibiotic Marker Screenable Marker Fluorescen ce Marker Colorimetric assay
- 5. Types of marker genes There are two types of marker genes Antibiotic resistance marker Antimetabolic marker Herbicide resistance marker Selectable markers Fluorescence marker Colorimetric marker Reporter markers
- 6. Selectable marker Selectable marker is required for maintenance of plasmid in the cell. It is a genes that confers resistance to particular antibiotics. Genes that make cells resistance to ampicillin, neomycin or chloramphenicol
- 7. Characters of Selectable Marker • Protect the organism from a selective agent that would normally kill it or prevent its growth. • Used for killing all cells that donot contain the foreign DNA. • Antibiotics are most common selective marker. • Non Antibiotics Marker can be 2 types • Endogenous marker • Nutritional marker
- 8. List of selectable marker gene, source of genes and substrate Selectable marker gene Source of genes Substrates not II E. coli Kanamycin hpt E.coli Hygromycin dhfr mouse Methotrexate epsps Petunia hybrida Glyphosate
- 9. Reporter marker • Also known as screenable marker. • A gene used to ‘tag’ another gene or DNA sequence, such as promoter. • Encode gene products whose enzyme activity can easily be assayed. • It is used as marker to confirm stable transformation.
- 10. Commonly Used Reporter marker Three types of Screening marker commonly used: 1. Green Fluorescent Protein (GFP) – Make cells glow green under UV light. – A specialized microscope is required to see individual cells. – Commonly used to measure gene expression. 2. GUS Assay – Use of beta-glucourinidase.
- 11. Commonly Used Reporter marker – AN excellent method for detecting a single cell by staining it blue. 3. Blue White Screening – Used in bacteria. – The lacZ gene makes cells turn blue in special media, e.g. X-gal – A colony of cells with the gene can be seen with the naked eye.
- 12. List of reporter marker gene, source of genes and detection assay Reporter marker gene Source of genes Detection assay ocs Agrobacterium tumefaciens Electrophoresis nos Agrobacterium tumefaciens Electrophoresis gus E.coli Colorimetric cat E.coli Autoradiography
- 13. Selectable marker vs Reporter marker Selectable marker Reporter marker • A gene whose expression allows one to identify cells that have been transformed or transfected with a vector containing the marker gene •A gene used to tag another gene or DNA sequence • Helps to distinguish between transformants and non- transformants •Helps to measure the amount of expression of transformed gene • Has its own promoter •Regulated under the promoter of the transformed gene • Ex:Antibiotic resistance gene,herbicide resistance gene •Ex:GFP and Luciferase