Cell Division
CELL GROWTH
Cells are limited in size by their SURFACE AREA and VOLUME ratio
– meaning that cells can get so large that they can no longer obtain enough oxygen and nutrients
– at which point, cells divide
CELL DIVISION – Process where a cell splits into two identical daughter cells
-Mitosis – division of the nucleus
-Cytokinesis – division of the cytoplasm
CHROMOSOMES
-Made of DNA, found in the nucleus
-Exist as CHROMATIN prior to cell division, then the chromatin coils and becomes CHROMOSOMES
-Number depends on organism (46 for humans, 78 for dogs…etc)
-Each chromosome has a copy of itself (giving it an X -shape), the two individuals CHROMATIDS are held together by a CENTROMERE
CELL CYCLE - events cells go through as they grow and divide.  Interphase –> Mitosis –> Cytokinesis
*Note that a cell spends the majority of its life in interphase, which is divided into three phases: Growth 1 (regular cell growth), Synthesis (DNA replicates), and Growth 2 (organelles double in number).
The time it takes for mitosis to complete varies by cell (and by organism), the process can take a few hours.
=======>Â Helpful to remember the steps of the cell cycle
Interphase
Organelles double in number to prepare for division
DNA replicates (copies)
Chromatin coils and becomes chromosomes
MITOSIS
CYTOKINESIS – the process by which the cytoplasm divides and one cell becomes two individual cells. The process differs slightly in plants and animals.
In plants, a new cell wall is built between the cells.
