Cold sores are caused by a herpes virus. There are eight different kinds of human herpes viruses. Only two of these, herpes simplex types 1 and 2, can cause cold sores. It is commonly believed that herpes simplex virus type 1 infects above the waist and herpes simplex virus type 2 infects below the waist.
The DNA is tightly coiled many times around proteins called histones that support the chromosome structure. The bound DNA units are called nucleosomes. Different kinds of organisms have different numbers of chromosomes. Humans have 23 pairs of chromosomes, 46 in all: 44 autosomes and two sex chromosomes.Each parent contributes one chromosome to each pair, so children get half of their chromosomes from their mothers and half from their fathers.he bound DNA units are called nucleosomes. Different kinds of organisms have different numbers of chromosomes. Humans have 23 pairs of chromosomes, 46 in all: 44 autosomes and two sex chromosomes.
During cell division, the identical copies (called a  sister chromatid pair ) are joined at the region called the centromere (2). Once the paired sister chromatids have separated from one another (in the anaphase of mitosis) each is known as a daughter chromosome.The short arm of the left chromatid (3), and the long arm of the right chromatid (4), are also marked.A chromatid (Greek khrÅmat- 'color' + -id) is one copy of a newly replicated chromosome, which typically is joined to the other copy by a single centromere.Before replication, one chromosome is composed of one DNA (double-helix) molecule.he short arm of the left chromatid (3), and the long arm of the right chromatid (4), are also marked. A chromatid (Greek khrÅmat- 'color' + -id) is one copy of a newly replicated chromosome, which typically is joined to the other copy by a single centromere.