Can someone explain the differences between chromatin, chromosomes, and sister chromatids? 

 

Chromatin is a long and continuous chain of DNA which is the shape that chromosomes take on before mitosis or meiosis. A chromatin is therefore a loose form of genetic material and the normal state of DNA,RNA and protein in the nucleus of the cells. Chromatin begins to form into chromosomes in the beginning of mitosis or meiosis, in metaphase and anaphase. Chromosome can be composed of two chromatids in most cases but can compose of one chromatid in the case of meiosis II.

Sister chromatids are the branches of one chromosome. A Chromatid is one half of two identical copies of replicated chromosome. During cell division, the identical copies are joined together at the region of the chromosome called the centromere. Joined chromatids therefore form sister chromatids.

DNA exists in Chromatin form in the nucleus. The chromatin condenses to form chromosomes during cell division. Chromosomes carries all the genetic material of the cell and transmits it to other cells and to other generations. The function of chromosomes is to make DNA fit in a cell. Chromatids however are less condensed in terms of packaging than the chromosomes. Chromosomes appear through out the cells life unlike the chromatid structure that appear only during interphase. The two sister chromatids attach with centromere and form a chromosome while a network of chromatins forms different chromatids