serves a very important function in the chromosome
. Without the centromere, segregation
of sister chromatid
s would not separate properly. Not much is currently known about the controls on the centromere during the different phase
s of mitosis and meiosis, but some is known about their structure and function in general. A few technical points about the centromere
- The centromere does not have to occur at the center of the chromosome. The human Y chromosome, for instance, has its centromere at one end.
- The DNA composition at the centromere can vary greatly from organism to organism. In humans, the centromere is usually either noncoding DNA or multiple copies of any of a number of enogenous retroviruses. In Saccharomyces cerevisiae, there is a short recognition sequence in a specific region of each chromosome called the CEN sequence; this sequence is the centromere region of the chromosome.
- The centromere region actually has a number of proteins bound to it during mitosis/meiosis; some bind the sister chromatids together, and some bind the kinetochores.
- In meiosis I, the centromeres of the homologous chromosomes do NOT touch. The homologous chromosomes are connected at chiasmata.