Question

What is in a Nucleus from Chromosomes to RNA?

Answer 1

Every cell in the human body contains a nucleus, with the exception of red blood cells, which lose this structure as they mature. Within the nucleus are tightly coiled threadlike structures known as chromosomes . Every chromosome has a long arm and a short arm, with a pinch point known as a ‘centromere’. Humans normally have 23 pairs of chromosomes, one member of each pair derived from the mother and one from the father . One those pairs consists of the sex chromosomes—with two X chromosomes determining femaleness, and one X and one Y determining maleness. The other 22 chromosomes are known as ‘autosomes’.

Each chromosome has within it, arranged end-to-end, hundreds or thousands of genes, each with a specific location, consisting of the inherited genetic material known as DNA. Some chromosomes are significantly larger than others, and some are more densely packed with genes. Under the standard system of identification, scientists have numbered these autosomes from 1–22 in size order (that is, the number of base pairs), with chromosome 1 being the largest (279 million base pairs, and an estimated 2968 genes). Of the sex chromosomes, the X (163 million base pairs and an estimated 1184 genes) is similar in size to chromosome 7, while the Y is the smallest chromosome (51 million base pairs and an estimated 231 genes).