The cell cycle is the life cycle of a cell. A cell spends its life growing, replicating DNA, performing other life functions, and dividing. For eukaryotic cells, the cell cycle consists of two general phases: interphase and the mitotic phase. Cell division is part of the life cycle for almost every cell. It is a more complicated process in eukaryotic than prokaryotic cells. Eukaryotes have multiple chromosomes and many organelles, all of which must be duplicated and separated for the cell to divide.
Mitosis: Process in which the nucleus of a eukaryotic cell divides.
Prophase: First phase of mitosis during which chromatin condense into chromosomes, the nuclear envelope breaks down, centrioles separate, and a spindle begins to form.
Metaphase: Second phase of mitosis during which chromosomes line up at the equator of the cell.
Anaphase: Third phase of mitosis during which sister chromatids separate and move to opposite poles of the cell.
Telophase: Last stage of mitosis during which chromosomes uncoil to form chromatin, the spindle breaks down, and new nuclear membranes form.
Cytokinesis: Splitting of the cytoplasm to form daughter cells when a cell divides.
Chromatin: Grainy material that DNA forms when it is not coiled into chromosomes.
Chromosome: Coiled structure made of DNA and proteins containing sister chromatids that is the form the genetic material of a cell goes through cell division.
Chromatid: One of two identical copies of a chromo-some that are joined together at a centromere be-fore a cell divides.
Centromere: Region of sister chromatids where they are joined together.
Homologous Chromosomes: Pair of chromosomes that have the same size and shape and contain the same genes.
Metaphase Plate: The invisible line at the equator(center)of the cell where the chromosomes containing the sister chromatids line up during metaphase.
Cell Plate: The structure that forms during cytokinesis in plants and eventually leads to the plasma membrane and cell wall of the two daughter plants.
For prokaryotes, the cell cycle is simple: the cell grows, DNA replicates, the cell divides.
For eukaryotes, the cell cycle is more complex. It includes two main phases: interphase and mitotic phase.
Interphase includes the growth phase1(G1),synthesis phase(S),and growth phase2(G2).A phase out of the cell cycle isG0,which the cell enters when it needs to rest temporarily or reaches a point in its life when it can no longer replicate.
There are regulatory proteins that control the cell cycle and make sure the cell is ready to move from one phase to the next. Cancer occurs when the cell cycle is not regulated.
A key part of cell division is to create copies of the genetic material.
The mitotic phase includes mitosis and cytokinesis.
Part of cell division is the replication and division of the genetic material. There are different names for the genetic material depending on the form it takes. It’s important to know the differences between these terms. Make sure you understand when to use each term!
(1) Single DNA strand.
(2) Chromatin strand (DNA with histones).
(3) Chromatin during interphase with centromere.
(4) Condensed chromatin during prophase. (Two copies of the DNA molecule are now present)
(5) Chromosome during metaphase.
Most prokaryotic cells divide by binary fission. Binary fission has three steps:
The two chromosomes segregate(separate)and move to opposite ends of the cell.
In eukaryotes, after the cell has grown large enough to divide, it enters mitosis. There are several steps in mitosis:
To remember the order of the phases of mitosis, remember this mnemonic: People Make A Team Prophase, Metaphase, Anaphase, Telophase
Cytokinesis occurs differently for animal cells and plant cells. For animal cells, a cleavage furrow forms and the cytoplasm pinches inwards until two daughter cells are formed. The process is called cleavage. For plant cells, a cell plate forms in the middle of the cell, and then a new plasma membrane and cell wall forms.
If you want to remember the six main steps of cell division, use this mnemonic:
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Interphase, Prophase, Metaphase, Anaphase, Telophase, Cytokinesis