ONION EPIDERMIS

ONION EPIDERMIS
INTRODUCTION
An eukaryote is an organism whose cells contain a nucleus and other structures (organelles) enclosed within membranes. Plant cells are eukaryotic cells that differ in several key aspects from the cells of other eukaryotic organisms. Their distinctive features include:
A large central vacuole a water-filled volume enclosed by a membrane known as the tonoplast which maintains the cell's turgor (provide structural support) and controls movement of molecules between the cytosol and sap. Stores useful material and digests waste proteins and organelles. The liquid inside the vacuole is known as cell sap, and its chemical composition usually is markedly different from that of the surrounding cytosol, as various substances are actively transported inside it. When full of sap, the vacuole causes the cell surface membrane to press against the cell wall (pressure helps to support plant). Sometimes it functions as a lysosome.

A primary cell wall containing cellulose. This makes the plant a more uniform and gives a regular shape.

Plastids such as chloroplasts that contain chlorophyll, the pigment that gives plants their green color and allows them to perform photosynthesis.

Specialized cell-to-cell communication pathways known as plasmodesmata,[3] pores in the primary cell wall through which the plasmalemma and endoplasmic reticulum[4] of adjacent cells are continuous.
The onion epidermal cell provides a protective layer against unwanted viruses that may harm the sensitive tissues. The clear epidermal cells consist of a single layer and contain chloroplasts, because the onion fruiting body (bulb) is used for storing energy, not photosynthesis.
DISCUSSION
Onions are root plants, they do not photosynthesize.
In biology methylene blue is used as a dye for a number of different staining procedures. It can also be used as an indicator.
Methylene blue stains both the nucleus and the cytoplasm of eukaryotic cells. The nucleus typically stains a deeper color.
Its purpose is to make cells show up against their background.