Human genome and disease

Human Genome and
Disease
Human Genome Organisation, Evolution and Variability
DNA
~ 2 meters in length in diploid human genome
- Length of linear naked DNA in average human diploid cell- still too long too fit
inside cell
- Nucleus is 50μm in diameter




How is DNA packaged and folded some more




Nucleosomes- form fundamental unit of chromosomal packaging




Coiling and Supercoiling of nucleosomes- Chromatin and
Chromosomes
Model 1- Supercoiling nucleosomes
- 10nm Nucleosomes supercoil to form 30nm superhelix – 6 nucleosomes
per turn
Model 2- Radial-loop scaffold model
- Non-histone proteins bind at regular intervals to form loops tethering
30nm superhelices

, Most condensed form- Metaphase Chromosomes




G-banding, Idiotypes and Karyotypes
Staining of metaphase chromosomes with GIEMSA STAIN
 Heterochromatic- AT-rich chromatin stains DENSER

 Euchromatic- GC- rich chromatic stains FAINTER




Karyotyping- process of pairing and ordering all chromosomes of organism
- Provide genome wide snapshot of individuals chromosomes
- Can be used to detect LARGE ABNORMALITIES in chromosomes



Genome- Sum total of ALL genetic information in organism