Human Cell (hsp)

Name of the school

Govt. Senior Secondary School ,Tal wara -1 (Hoshi arpur )

Prepared by: Ashok Kumar (Science Master) Yashpal Singh (Science Master)

Introduction:-

Our earth is inhabited by different kinds of living organisms such as bacteria, protista, fungi, plants and animals. The bodies of living organisms are made up of microscopic units called cells.

HUMAN CELL Definition:-The cell is the basic structural and functional unit of living organisms. cell is made of life giving

CHARACERISTICS OF CELL:

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They contain a set of genes:-All cells contain genetic material in the form of either DNA or RNA which contain genes. Genes are self replicating units and are located on the chromosomes. They contain a limiting plasma membrane:-Every type of cell is bounded by plasma membrane which is a living, ultra thin membrane of molecules of lipids and proteins. They contain a metabolic machinery:All cells contain a cytoplasm which is needed for sustaining life activities such as feeding, respiration, excretion etc.

Cellular organisms are divided into two main types: 1. 2.

Prokaryotic cell Eukaryotic cell

Prokaryotic Cell These have primitive and incomplete cells. It contains single chromosome. In these cells nucleolus is absent. The size of the cell is generally small. Cell division takes place by fission or budding.

Diagram of Prokaryotic cell:-

Eukaryotic Cell 

These have advanced and complete cells. These cells contain membrane bound cellular organelles and are called eukaryotic cells. The size of cell is generally large. It contains more than one chromosome. Cell division occurs by meiotic or mitotic cell division. These cells are found in unicellular and multi cellular plants and animals and contain plasma membrane, nucleus, DNA.

Diagram of eukaryotic cell:-

Structure of cell:All cells have three major functional regions:• The Plasma Membrane • The Nucleus • The Cytoplasm

Plasma Membrane: Plasma membrane is the outer covering of each cell. It is present in both plant and animal cells. It separates contents of a cell from the surrounding medium.  Functions:-The main function is to regulate the movement of molecules inside and outside the cell.  It helps in maintaining distinct composition of the cell.

Nucleus

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The nucleus, present in eukaryotic cells, is a discrete structure containing chromosomes, which hold the genetic information for the cell. Separated from the cytoplasm of the cell by a double-layered membrane called the nuclear envelope, the nucleus contains a cellular material called nucleoplasm.

Cytoplasm

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part of the cell which occurs between the plasma membrane and nuclear envelope is called the cytoplasm. It consists of an aqueous substance, the cytosol.

Cytoplasm contains:

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Cytosol:- it is the soluble part of cytoplasm. It forms the ground substance or background material of the cytoplasm and is located between the cell organelles. Cell organelles: 1. Endoplasmic reticulum:-Inside the cell there exits a membranous network enclosing fluid-filled lumen which almost fills up the intracellular cavity. It is called endoplasmic reticulum. 2. Ribosome:-They are dense, spherical and granular particles which occur freely in the matrix or remain attached to the endoplasmic reticulum.

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3.Golgi apparatus:-It consists of a set of membrane-bounded, fluid filled vesicles, vacuoles and flattened cisternae.

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4.Lysosomes:-These are simple tiny spherical saclike structures evenly distributed in the cytoplasm.

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5.Mitochondria:-The mitochondria are tiny bodies of varying shapes distributed in the cytoplasm.

Acknowledgement 

We are thankful to Mr. Gulshan Rai (Computer faculty), Mr. Narinder Singh (Computer Faculty) and Miss Amita (Computer Teacher ) for their expert guidance and co-operation.

BIBLIOGRAPHY

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