Parts of Cells

If we put a cell under a microscope , there are three features that you could observe clearly in nearly every cell . 

• These are : Plasma Membrane , a Nucleus , and Cytoplasm
• Cell organelles are also present in nearly every cell ( except prokaryotes ).
• These vary from cell to cell . 
• In plant cells you can also observe an extra covering called the Cell wall .

Let us learn about the basic parts of a cell first:

Cell Membrane / Plasma Membrane

Every cell has a membrane around it to keep its contents separate from the external environment .

•  The cell membrane is the outermost covering of an animal cell. 
• It encloses the other components of the cell , such as the nucleus and the organelles.
• It is also known as the Plasma membrane .
• The cell membrane is flexible and its shape can be changed as needed. 
• The plasma membrane is made of substances called lipids and proteins which lend it flexibility .

The functions of the Cell membrane are as follows:

• Protecting the integrity of the interior cell.
• Providing support and maintaining the shape of the cell.
• It acts as a semi - permeable membrane that allows the entry of only selected substances into the cell.
• Helps cells to catch/absorb food by changing its shape .

For Example - An amoeba catches its food by changing its shape and using pseudopodia to capture food.

Nucleus

• The Nucleus can be described as the brain of the cell . 
• It is a membrane-bound (covered by a sheath ) structure.
• It contains the cell’s hereditary information (characteristics/genes obtained from parents)  and controls the cell’s growth, reproduction and other essential functions.
• The membrane covering the nucleus is called the Nuclear membrane .
• The nuclear membrane separates the cytoplasm from the contents of the nucleus .

Cytoplasm 

The cytoplasm is the fluid content inside the plasma membrane . 

• It is a semi-liquid jelly-like material , between the nucleus and the cell membrane. 
• All cell organelles such as endoplasmic reticulum, mitochondria, ribosomes, vacuoles, etc. float within the cytoplasm .

Cell Wall 

It is the outermost covering of a plant cell . 

• It separates the interior contents of the cell from the exterior environment . 
• The cell wall is permeable in nature which means it allows the passage of most materials through it .
• The cell wall is made up of a substance called Cellulose .
• Cellulose gives it strength and rigidity .

Here are a few functions of the cell wall:

• It provides shape, strength and rigidity to the cell.

(The absence of the cell wall is the reason why animal cells are irregularly shaped . They have no support ).

• It provides protection from any physical stress as well as from the external environment .
• Controls the swelling of the cell during water intake . Without it, the cell would burst .
• Prevents water loss from cell by trapping in the water.
• It transports substances across different cells.

Apart from these 4 parts that are present in every cell,  a cell may also contain cell organelles . 

Each organelle has a separate function that it performs for the cell.