Lab-2- The Plant cell. (Prokaryote and Eukaryote cell

Lab-2- The Plant cell.
(Prokaryote and Eukaryote cell)
What Are Cells?
All living things are constructed of cells; at least one (unicellular) or many (multicellular). Cell Theory, the very basic scientific truths about life and its smallest units, goes as follows:
1. All organisms are composed of one or more cells.
2. Cells are the basic unit of structure and function in organisms.
3. All cells come only from other cells.
Two Types of Cells
All cells fall into one of the two major categories. They are either prokaryotic or eukaryotic.
Prokaryotic Cells
Prokaryotes are evolutionarily ancient. These cells are simpler than eukaryotes and don’t contain a nucleus or any other membrane-bound organelles. Modern day bacteria (Eubacteria) and bacteria-like Archaea are prokaryotic organisms.
Eukaryotic Cells
Eukaryotes are more complex, having evolved from an ancestral prokaryote. Eukaryotic cells are the tiny units of life comprise most of the living things we are familiar with, such as animals, plants, fungi and protists (animal-like microbes).

The organelles in Eukaryotic cell. ( figure -1-)
Cell Wall. The cell wall encloses and protects the cell contents and plays a vital role in cell division and cell expansion. Composed of overlapping cellulose microfibrils, other polysaccharides and varying amounts of lignin, the cell wall is a relatively rigid structure in mature cells. It may vary in thickness and has pits that function in communication between cells. The region between the primary walls of adjacent cells, the middle lamella , is composed of a cementing substance called pectin. Other substances that may be present in the cell wall are gums, resins, silica, calcium carbonate, waxes and cutin, and both structural protein and enzymes (which are also proteins). There may be intercellular spaces between walls of bordering cells.
Plasma Membrane. A semipermeable membrane encloses the cytoplasm within a cell. It is composed of variable amounts of fat type molecules (lipids) and proteins, and has within it channels for the movement of ions such as potassium (K+), calcium (Ca 2+), and hydrogen (H+).
Cytoplasm. The cytoplasm is a liquid, gel like substance and contains several types of organelles; smooth or rough endoplasmic reticulum , rough referring to attached ribosomes on the ER (endoplasmic reticulum) and free ribosomes.
Vacuole. In a mature plant cell, one large vacuole usually occupies most of the space within the cell. It is surrounded by a single-layered membrane, the tonoplast, and contains cell sap composed of water, sugars, and various organic and