The Cell Cycle and its Regulation

Your cells have to divide when you're growing, to heal wounds, and to replace dead cells. But how do cells know when to divide and when not to divide? We can't have cells just growing willy-nilly! That's what cancer is, and that's bad. Luckily, cells obey something called the cell cycle, which is regulated by a variety of signaling molecules, which tell the cell when to divide and when to chill out. Let's look at the phases of this cycle and some of its regulatory mechanisms now.

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[jarednicholas]

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[aquila]

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[Shub_inc]

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[JEPTEPKENY]

Quick question-
Chromosomes can be monads (a single chromatid) or dyads (sister chromatids held together by a centromere; a dyad has two identical strands of DNA held closely together in a location called the centromere). When a cell is in the G1 or Gap 1 Phase of their cell cycle, the nucleus contains monads but during the S phase the DNA is synthesized into the dyads that are seen in the G2 or Gap 2 phase.
*The strands are identical assuming that no copying errors (mutations) have occurred during the S phase of the cell cycle
Familiarize yourself with the conditions of a cell’s chromosomes during the G1 and G2 phases of the cell cycle.

The 4 phases of mitosis:
Prophase = chromosomes condense
Metaphase = chromosomes line up in the middle of the cell with reference to the two poles (the equatorial plate or metaphase plate) with each chromosome on its own spindle fiber (by itself)
Anaphase = separation of the chromosomes
Telophase = formation of two nuclear envelopes around the two chromosomal clusters and then the cell divides (cytokinesis)

Questions:
In humans, there are 46 chromosomes in the nucleus of a cell. When the cells are in the G1 phase the 46 chromosomes are 46 monads which are 46 single chromatids. During the S Phase the 46 monads become 46 dyads which are 46 sister chromatids that will split during the M Phase/Mitosis. What is in the nucleus of the cell after mitosis?

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[KingMB_XJ_Official]

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