martes, 10 de marzo de 2009

Diferences between plants cells and animal cells:



Plant cells are much like animal cells, except for 3 important differences.
A) Plant cells have cell walls, which make them appear rectangular-shaped. These structures are composed of cellulose, hemicellulose, and a variety of other materials.
B) Plant cells have chlorophyll, the light-absorbing pigment required for photosynthesis. This pigment is contained in structures called chloroplasts, which makes plants appear green.
C) Plants cells have a large, central vacuole. While animal cells may have one or more small vacuoles, they do not take up the volume that the central vacuole does (up to 90% of the entire cell volume!). The vacuole stores water and ions, and may be used for storage of toxins



Definition of cell:


CEll: Biology basic unit of living thing: the smallest independently functioning unit in the structure of an organism, usually consisting of one or more nuclei surrounded by cytoplasm and enclosed by a membrane. Cells also contain organelles such as mitochondria, lysosomes, and ribosomes.



Definition of Mitosis:


Mitosis:
Process in which a cell’s nucleus replicates and divides in preparation for division of the cell. Mitosis results in two cells that are genetically identical, a necessary condition for the normal functioning of virtually all cells. Mitosis is vital for growth; for repair and replacement of damaged or worn out cells; and for asexual reproduction, or reproduction without eggs and sperm.