Each of the sister chromatids gets attached to the nuclear envelopes.The chromosomes appear like strings with beads and the beads are known as chromomeres.The chromosomes condense and become compact and visible hence making it possible to distinguish between sister chromatids.It the phase of a replicated chromosome condensation.Leptotene- This is the first stage of prophase I and the shortest phase of prophase I. There are five phases that define prophase I.įigure: Prophase 1 of Meiosis. This is the phase of homologous chromosome pairing and exchange of DNA to form recombinant chromosomes. The mitotic spindles also continue growing further and some of the interpolar microtubules start to capture the chromosomes.The nuclear envelope also breaks down releasing the chromosomes.This is the stage where the final chromosome condensation takes place making them very compact.The cell then redirects cellular energy from the cell’s’ metabolism to cell division mechanisms.This is an indication that the nucleus is starting to breakdown.During the late prophase (prometaphase), part of the nucleus where the synthesis of ribosomes takes place to disappear.Generally, the mitotic spindles are made up of hundreds to thousands of fibrous microtubules and microtubule-associated proteins (MTP) which function in nucleation, transportation, dynamics, and cross-linking of microtubule networks.Eventually, the mitotic spindles separate the sister chromatids as the cell cycle continues.The microtubules gather at the opposite poles of the cell and start to form the spindle apparatus at the foci.The formation of mitotic spindles in plants is a bit different.Cells that lack centrioles, the chromosomes nucleate the microtubule assembly into the mitotic apparatus.Additionally, both centrosomes have interpolar microtubules that interact with each other and join the sets of microtubules to form the basic structure of the mitotic spindles.On separation, the centrosomes move to opposite poles of the cell, mediated by the radial microtubules known as Kinetochore, found on each centrosome.The microtubules of the interphase hold the replicated centrosomes during separation.

This helps the centromeres to move to opposite poles.įormation of mitotic spindles – mitotic spindles are fibrous.The motor proteins convert chemical energy in the form of ATP to mechanical energy to move along the microtubules.The centromere associated motor proteins track the centromere movement and the formation of spindles during chromatin separation.The moving is driven by motor proteins that are associated with the centromere.The centromeres that are replicated from the interphase move away towards the opposite poles of the cell.Tubulins act by incorporating microtubules to the nucleus.At the centromere are microtubules that function by recruiting tubulins.Chromosome condensation forms two sister chromatids which are X-shaped and joined at a point known as a centromere.Topoisomerase specifically topoisomerase 2 helps in the relaxation and unlinking of supercoils formed in interphase, cutting, and releasing of the DNA duplex.

Condensins are complex proteins that play a key role in the cell cycle, and majorly the separation of the chromosomes, chromosome condensation, maintaining the structural integrity of chromosomes, and the resolution of DNA topography during intertwining.

Chromosome condensation is done by the help of condensins complexes which include condensins and topoisomerase.

Condensation forms sturdy, elastic chromosomes to prevent damage and breakage caused by the force of pulling microtubules and cytoplasmic drags experienced during mitosis.

Condensation allows structural reorganization to separate the identical sister chromatids, a mechanism known as chromatid resolution.

Chromosome condensation is the compacting of the chromatin into well-defined rod-shaped structures known as chromatins.

The interphase stage allows DNA replication which uniformly entangles (intertwines) the DNA molecules, for easy separation during mitosis.

This is a mechanism that involves the condensing of the DNA that is synthesized during interphase.

In animal cells, prophase is the first phase of mitosis and the second phase of mitosis in plant cells.

Prophase picture