Tag: the mitotic cell cycle

An inactivated X-chromosomes : female have XX chromosomes and male have XY chromosomes ,for balance Xlinked gene between male and female,one X chromosome undergo inactivated during the female embryo development this is termed as X chromosomes inactivation

(a) Basic Fuchsin-  It is a green crystalline dye. It includes staining of tissues sections.

Chromosome condensation is the dramatic re-organization of the long thin chromatin strands into the compact short chromosomes that occur in mitosis and meiosis. Here, the unfolding of proteins takes place, the DNA coils, dehydration takes place. However, there is no addition of water molecule or hydration that takes place during condensation.

Centromere provides structure to the cell. The sister chromatids are linked together at the centromere. During mitosis, spindle fibers attach to the centromere via kinetochore. Their physical role is to act as the site of assembly of the kinetochore, a highly complex multiprotein structure that is responsible for the actual events of chromosome segregation, i.e., binding microtubules and send signals to the cell cycle machinery.

Chromosomes are the carrier of genetic information in form of DNA. The secondary constrictions are used as a point of identification of chromosomes. These are always constant in their positions and hence, can be used as markers that identify particular chromosomes. A satellite chromosome or SAT chromosome has a chromosome segment that is separated from the main body of the chromosome by such a secondary constriction.

Chromosomes are the genetic material present in the nucleus of a cell. It is composed of DNA and protein. The functional segment of DNA is known as a gene. The size of chromosomes varies from as small as 0.1$\mu$m to as big as 15$\mu$m in length.

The largest normal metaphasic chromosome has the size of 30nm with the base of the nucleosome core particle consists of the 146 base pairs of DNA. During metaphasic state, when a chromosome in its most condensed state can range in size between 130,000 base pairs in the endosymbiotic bacteria, then the chromatin can be further condensed by coiling into 30nm in fibres.
So, the correct answer is option D.

• Stains are used in the microscopic studies of different components and organelles within a cell.

Chromonema is spirally coiled central filament that extends the entire length of a chromosome and on which the genes are located. During mitotic prophase, the chromosome material appeared as thin filaments which are known as chromonema. This term is introduced by Vijdovsky in 1912.