File:Human idiogram-chromosome 21.jpg

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Human Idiogram - Chromosome 21

Idiogram (karyogram) - A drawing or photograph of the chromosomes of a particular cell.


Trisomy 21 Links: Trisomy 21 | Image T21 female karyotype | Image T21 male karyotype | chromosome 21 | Category:Trisomy 21 | Genetic Abnormalities | Prenatal Diagnosis | Genome View - chromosome 21

Chromosome 21

  • the smallest human chromosome
  • about 47 million base pair
  • about 1.5 % of the total DNA in cells
  • contains between 200 and 300 genes (of human estimated 20,000 to 25,000 total genes)
  • trisomy 21 or Downs Syndrome - additional copy of this chromosome
  • partial monosomy 21 - missing segment of the chromosome in each cell
  • ring chromosome 21 - circular structure, occurs when there are two breaks in a chromosome and the ends of the chromosome then fuse together


Trisomy 21 Links: Trisomy 21 | Image T21 female karyotype | Image T21 male karyotype | chromosome 21 | Category:Trisomy 21 | Genetic Abnormalities | Prenatal Diagnosis
Human Chromosomes: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | X | Y  
Idiogram Chromosome Banding - The term refers to the light and dark pattern, seen after staining with a dye, of individual chromosomes identified in metaphase. It is only in meiosis and mitosis during metaphase that chromosomes can be easily identified, during the normal cell life (interphase) the chromosomes are unravelled and distributed within the nucleus in chromosome territories. A band is that part of a chromosome which is clearly distinguishable from nearby regions by appearing darker or brighter with one or more banding techniques.
Human Idiogram: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | X | Y
Genetic abnormality locations: 1-4 | 5-8 | 9-12 | 13-16 | 17-20 | 21-XY | sSMC
Inheritance Pattern images: Genetic Abnormalities | autosomal dominant | autosomal recessive | X-linked dominant (affected father) | X-Linked dominant (affected mother) | X-Linked recessive (affected father) | X-Linked recessive (carrier mother) | mitochondrial inheritance | Codominant inheritance | Genogram symbols | Genetics
Links: Genetics | Abnormal Development - Genetic

Cite this page: Hill, M.A. (2024, April 13) Embryology Human idiogram-chromosome 21.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Human_idiogram-chromosome_21.jpg

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G

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current13:51, 23 April 2011Thumbnail for version as of 13:51, 23 April 201131 × 142 (2 KB)S8600021 (talk | contribs)==Human Idiogram - Chromosome 21== Idiogram- A drawing or photograph of the chromosomes of a particular cell. This drawing does not include the mitochondrial DNA. {{Human chromosomes}} Category:Genetics Category:Chromosome [[Category:Molecula