Parts of cell & How can the cell perform its functions ?

The cell

It the smallest functional and building unit in all living organisms , The cell is characterized by the ability to  grow , It can reproduce , It can respond to the external stimuli and perform the different metabolic processes .

Parts of cell

The cell is made up of a protoplasmic mass surrounded by the cell membrane , The protoplasm is differentiated into parts which are nucleus and cytoplasm , Cytoplasm contains a group of cellular structures called cell organelles .

Cell structure

The cell wall and cell membrane ( plasma membrane ) .

The nucleus consists of nuclear envelope , Nucleolus , Nucleoplasm and Chromatin .

Cytoplasm contains membranous organelles and non-membranous organelles , membranous organelles ( contains Endoplasmic reticulum , Golgi body , Lysosomes , Mitochondria , Vacuoles and Plastids ) , non-membranous organelles ( includes  Ribosomes and Centrosome ) .

Parts of the cells

Parts of the cells

Cell walls and plasma membranes

Cell wall 

The cell wall surrounds the plant cell , algae , fungi and some types of bacteria , It is mainly composed of cellulose fibres .

Cell wall functions
  • It supports and protects the cell .
  • It allows the passage of water and dissolved substances through it easily because it is pitted .

The perennial trees such as palm trees are characterized by containing cell wall that play an important role in protecting the cells , making them withstand to wind and other weather factors , these walls provide the cells with strong support .

The small herbal plants are characterized by containing cell walls with little elasticity that makes them able to maintain their shapes as they are exposed to strong wind .

Cell membrane ( plasma membrane )

It surrounds the cytoplasm of plant and animal cells , Cell membrane is a fluid structure similar to a layer of oil because the phospholipids forming it are a fluid substance , It is a thin membrane consisting of :

  1. Two layers of the fluid phospholipid molecules , each of them consisting of Hydrophilic heads and Hydrophobic tails , Hydrophilic heads ( soluble easily in water ) meet the water medium in and out the cell , Hydrophobic tails ( insoluble in water ) and present inside the membrane .
  2. Molecules of protein are embedded between the molecules of phospholipids , where some of them work as cell identification sites for different substances such as nutrients , hormones and others , Some others work as gates to pass the substances into and from the cell .
  3. Cholesterol molecules linked with phospholipid molecules for maintaining the cell membrane cohesive and intact .
Cell membrane Functions

It covers the cell and separates its components from the surrounding medium , So , it prevents the spreading out of cytoplasm outside the cell .

It performs a basic role in organizing the passage of the substance to and from the cell .


Nucleus is the most obvious organelle in the cell that can be seen under the microscope ,  It has a spherical or oval shape and it is located at the middle of the cell .

Nucleus structure

The nucleus is composed of :

Nuclear envelope is a double membrane separates the contents of the nucleus from cytoplasm , There are several tiny pores in it through which substances pass between the nucleus and cytoplasm .

Nucleolus is responsible for synthesis of ribosomes which play an important role in protein synthesis , So , more than one nucleolus may be found in the nucleus especially in the cells forming and secreting proteins as enzymes and hormones .

Nucleoplasm is a transparent gelatinous fluid contains the chromatin .

Chromatin is minute tangled filaments coiled around themselves , during cell division and it changes into rod-like structures called chromosomes .

The chromosome

Chromosomes were called with this name because they stain by basic dyes , So , they appear coloured making them more clearly seen during cell division .

During metaphase of cell division , The chromosome appears consisting of two filaments , each filament of those is called chromatid , They are joined together by a central part called centromere .

Each chromatid is composed of the nucleic acid DNA coiled around protein molecules called histones .

DNA carries the genetic information ( genes ) that  control the shape and structure of the cell and organize its vital activities , Genetic traits are transferred through them from a generation to another by reproduction .

Chromosome form the chromatin reticulum in cell nucleus , Chromosome is not consisted of two chromatids in all phases of mitosis where chromosome is consisted of two chromatids at the beginning of mitosis till its metaphase .

Chromosome becomes consisting of one chromatid in anaphase , telophase and called daughter chromosome , At the beginning of each new cellular division , its genetic material is duplicated to become consisted of two chromatids .

The cytoplasm

You can read this article about the cytoplasm

Non-membranous organelles and membranous organelles in the cytoplasm


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