Chromosome
These are threadlike structure containing DNA and genes. DNA has a negative charge distributed along its length and positively charged protein molecule called histones and bond to it. Between division of the nucleus each chromosome contains one DNA molecule. Before the nucleus divides the DNA replicates such that at nuclear division the chromosomes are a double structure, containing two identical DNA molecules. The two parts of the chromosomes are referred to as chromatids. Each chromatid one of the two identical molecules. Species in which there are two sets of chromosomes are referred to as diploid given symbol 2n A few simple organisms have only one set of chromosomes and are referred to as haploid symbol n. Garments either sex are haploid.
Chromatin
Chromatin is a genetic material or a macromolecule comprising DNA wound around histones (basic) proteins, which constitute chromosomes in the nucleus of a eukaryotic cell. This chromatin is located within the cell nucleus. The main functions of this genetic material include:
- Control the DNA replication and gene expression.
- Support the DNA molecule to permit the process of the cell cycle
Difference between Chromosomes and Chromatin
| Chromosome | Chromatin |
| Chromosomes are condensed chromatin fibres. | Chromatin is composed of nucleosomes, which are a complex of DNA and proteins. |
| Chromosomes are thick, compact and have a ribbon-like shape | Chromatin is a thin and long fibre |
| Distinctly visible during cell division. | Found throughout the cell cycle. |
Telomeres
Repeated short base sequence at end of chromosome (by telomerase).
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- permit continued replication
- prevent loss of genes
- protect ends of chromosomes from being, degraded
Centromere
Region where chromatids are held together. A constricted region of DNA or a structure in a chromosome, which plays an essential role in the segregation of chromosomes during the process of the cell cycle in eukaryotic cells. The centromeres are the point of attachment of the kinetochore. The main functions include the attachment of sister chromatids, and it is the site for the attachment of spindle fibre.
Kinetochore
Protein structure found on centromere of chromatid to which microtubules attach. Two kinetochores at centromere on each chromatid during metaphase. Microtubules extend from kinetochore to the poles of spindle.