Chromosomes
Figure 8 Chromosome
a. DNA is organized in bundles called chromosome. DNA is tightly packed in these bundles to fit in the nucleus of the cell. b. We have 46 chromosomes in our human genome, 22 autosomes from each parent and one sex chromosome. A karyotype is a picture of, the 23 chromosomes, the human genome. Each chromosome is numbered on the karyotype and organized by size.
DNA molecules are organized into tightly packed bundled called chromosomes. Our chromosomes are long pieces of DNA located within the nucleus of every cell.(see Figure 8a) Each cell has 23 pair of chromosomes or 46 chromosomes, which is what we call our human genome. We inherit 23 of our chromosomes (1 member of each pair) from each of our parents. As a result, every person has two of each gene, one from each parent. Twenty two chromosomes come from our biological mother and twenty two chromosomes from our biological father. These 22 chromosomes are called autosomes. The 23 rd chromosome is called the sex chromosome. This chromosome determines one's sex, XX for a girl or one X and one Y for a boy. When genes are studied or analyzed, a picture of the chromosomes numbered and arranged by size is often used. It is an excellent tool to study the human genome and chromosomal structures. This picture is called a karyotype. 21 (see Figure 8b)
Our human genome refers to the total DNA that comprises our 46 chromosomes. A common analogy of the human genome is, to think of the genetic code as a library, the chromosomes would be the books in the library, and the genes would be the chapters of each book containing directions for one particular function of the body. 22
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