Difference between genetic linkage and physical map

Gene mapping means the mapping of genes to specific locations on chromosomes.
Such maps indicates the positions of genes in the genome and also distance between them.

1. Difference between Genetic linkage and Physical map Presented to Dr. M. Kanimoli Mathivathana ., Assistant Professor Department of Plant Breeding & Genetics Presented by ROHITH S (2017021054)

2. COLLEGE OF AGRICULTURAL TECHNOLOGY, ( Affiliated to Tamil Nadu Agricultural University,Coimbatore-3) (Accredited by Indian Council of Agricultural Research, New Delhi) Kullapuram (Po), Via Vaigai Dam, Theni - 625 562.

3. What is genome mapping Why genome mapping

4. Gene mapping means the mapping of genes to specific locations on chromosomes. Genetic Mapping Such maps indicates the positions of genes in the genome and also distance between them. It is very important in the understanding of genetic diseases. To identify the defected gene. Chromosomes 22 pairs & XY What? Why?

5. The first genetic maps, constructed in the organisms such as the fruit fly, used genes as markers.

6. Gene mapping Linkage mapping Physical mapping G-1 / G-2 Closely Distantly related Relative distance between genes. Difference between genes. G-1 G-2 Chromosome chromosome 5 X Eg: Exact location of a gene in chromosomes

7. Genetic markers Very important tool in mapping of genes They are simply a gene present in different locations of chromosomes Varying in expression visible biochemical Molecular G1 G2

8. Linkage Mapping Linkage 2 genes are linked or not?? G1 / G2

9. G1 G2 G3 G4 x x x x x x Crossing over x x x x x x G1 G2 G2 G1 G3 G4 G3 G4 Linear chromosome Recombinant type Parental type Visible, Biochemical or Molecular Expression Assort independently They do not Assort independently

10. Recombination frequency = Total no of recombinant type Total no of offsprings Parental frequency = Total no of parental type Total no of offsprings x 100 x 100 eg Rec freq = r r + p (10+14) = (40+36) + (10+14) 24 = 24+76 x 100 x 100 x 100 = 24% ( Recombination frequency, Strength of linkage ) < 50% - Recombinant type > 50% - Parental type

11. Recombinant % - Parental % - Recombinant % - Parental % - Inference: Here the two markers (genes) are linked or they are placed so closely..

12. Map Distance One unit of map distance is equivalent to 1% crossing over Map units are often referred to as centimorgan ( cM ) in honor of the work of Thomas Hunt Morgan, a famous Drosophila geneticist. The distance between two gene is calculated according to the percentage of crossing over, because cross over frequency is directly proportional to distance between genes. eg : 24 cM 24cM G1 G2

13. Linkage mapping Physical mapping Cytogenetic map DNA sequencing Genes located by FISH Genetic markers Overlapping fragments Chromosome bands

14. Genetic Map Physical map It is the calculated map distance based on crossover percent between two linked genes Actual physical distance between linked genes This map distance highly varies as frequently of crossing over varies in different segment of chromosomes and it is only a predicted value The physical distance of linked genes bears no direct relationship to the map distance calculated on the basis of crossover percentages Linear order is identical as in physical map Linear order is identical as in genetic map Distance measured in centiMorgans ( cM ) Distance measured in bp ( Mbp ) Relative distance between two genes Exact location of a gene in chromosomes

15. List of sequenced plant genomes

16. S No Crops Genome size Genes predicted Year of completion 13 wheat 14500Mb 107,891 2018 14 Long grain rice 430Mb 2002 15 Short grain rice 430Mb 2002 16 Maize 2300Mb 39,656 2009 17 sorghum 730Mb 34,496 2009 18 cumbu 179Gb 38579 2017 19 sunflower 3.6Gb 52,232 2017 20 lettuce 2.5Gb 38,919 2017

17. References: http://www.sciencedirect.com/topics/neuroscience/genetic-mapping http://sciencing.com/rna-definition-function-structure-13718420.html https:/www.genome.gov/about-genomics/fact-sheets/Genetic-Mapping-Fact-Sheet Griffiths, AJF (2000). An introduction to Genetic Analysis (7 th edition). W.H.Freeman . 205-211 P.S.Verma , P.K.Agarwal (2008) “Genetics”, Oxford Publication, New Delhi. Varshney RK, Shi C, Thudi M, Mariac C, et al. (2017). "Pearl millet genome sequence provides a resource to improve agronomic traits in arid environments".  Nature Biotechnology . 969–976

18. https://www.genetics.org/content/148/1/479 https://link.springer.com/article/10.1007/BF03191152 http://www.ncbi.nih.gov/m/pubmed/10857196 https://www.medicinenet.com/script/main/art.asparticlekey=3567 https://journals.plos.org/plosone/articleid=10.1371/journal.pone.0139666 http://www.g3journal.org/content/7/3/843 http://www.yourgenome.org/facts/how-do-you-map-a-genome

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