It is a genetic condition caused when an unusual cell division result in an extra full or even partial copy of chromosome 21. This extra genetic material causes the developmental changes and physical ...

A human body contains 46 chromosomes which exist in a pattern of 23 pairs. A third copy of chromosome 21 exists with Down syndrome, which results in 47 chromosomes overall. Dr. Khanna explains that ...

Chromosome 21 is the smallest human chromosome, and procedures for examining human chromosomes were still being developed during the first part of the century. Many early cytologists had ...

What is the structure of a chromosome? Why does the total number of chromosomes in a cell matter? Learn how chromosomes self-organize within single cells, and how these patterns help us detect ...

Human biological sex is determined by the sex chromosomes X and Y. In most cases, females possess two X chromosomes, while males have one X and one Y. However, there is some evidence that the Y ...

In particular, it explains that humans have one fewer chromosome pair in their cells than apes, due to a mutation found in chromosome number 2 that caused two chromosomes to fuse into one.

It is caused by an extra chromosome at chromosome 21. This is not inherited and happens by chance during the formation of egg cells, giving them an extra chromosome (24 total). When fertilised by ...