CELL ORGANELLES AND FUNCTIONS

DONE BY

LAASYA VEMAVARAPU

IX CLASS

CELL - THE FUNDAMENTAL UNIT OF LIFE

• Cell is called the fundamental unit of life.

• A cell is capable of independent existence and can carry out all the functions which are necessary for a living being. A cell carries out nutrition, respiration, excretion, transportation and reproduction; the way an individual organism does. Unicellular organisms are capable of independent existence which shows a cell’s capability to exist independently. Due to this, a cell is called the fundamental and structural unit of life. All living beings are composed of the basic unit of life, i.e. cell.

CELL THEORY (SCHLEIDEN, SCHWANN AND VIRCHOW)

• All living organisms are composed of one or more cells.• The cell is the basic unit of structure, function, and organization in

all organisms.• All cells come from preexisting, living cells.

SHAPE AND SIZE OF CELLSCells come in all shapes and sizes. While most of the cells are spherical in shape, cells of various other shapes are also found. Most of the cells are microscopic in size, i.e. it is impossible to see them with naked eyes. Some cells are fairly large, e.g. a neuron in human body can be as long as 1 meter. The egg of an ostrich is the largest known cell of a living animal and an average egg is 15 cm long and 13 cm wide.

WHAT THE CELL CONTAINS???A CELL IS ENCLOSED IN A MEMBRANOUS CASING AND IS FILLED WITH A LIQUID SUBSTANCE WHICH IS CALLED THE CYTOPLASM. THERE ARE MANY CELL ORGANELLES IN A TYPICAL CELL. SOME OF THE MAIN STRUCTURES OF A CELL ARE AS FOLLOWS

PLASMA MEMBRANE The cell membrane (also known as the plasma membrane or

cytoplasmic membrane) is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells.

CELL WALL Cell wall is made of cellulose. It is somewhat hard but

permeable to most of the substances. Cell wall is available in plant cells and in cells of bacteria and fungi.

NUCLEUS Nucleus is covered by double membrane; called nuclear

membrane. The fluid which is inside the nucleus is called nucleoplasm. Nucleus contains chromosomes which are important for the functioning of a cell. Chromosomes contain genes which are the carriers of genetic information. Nucleus plays an important role during cell division. Nucleus controls all the functions of the cell.

CYTOPLASM Function of Cytoplasm. The jelly-like fluid that fills a cell is

called cytoplasm. It is made up of mostly water and salt. Cytoplasm is present within the cell membrane of all cell types and contains all organelles and cell parts.

ENDOPLASMIC RETICULUM The endoplasmic reticulum serves many general functions,

including the folding of protein molecules in sacs called cisternae and the transport of synthesized proteins in vesicles to the Golgi apparatus.

GOLGI APPARATUS The Golgi complex is referred to as the manufacturing and the

shipping center of the eukaryoric cell.

The Golgi apparatus or the Golgi body or Golgi complex or Golgi is a cellular organelle present in most of the cells of the eukaryotic organisms.

The Golgi bodies were identified by an Italian biologist Camillo Golgi in the year 1897 and was maned after him in the year 1898.

The Golgi complex is responsible inside the cell for packaging of the protein molecules before they are sent to their destination. This organelles helps in processing and packaging the macromolecules like proteins and lipids that are synthesized by the cell, It is known as the 'post office' of the cell.

The major function of the Golgi body is to modify , sort and package the macromolecules. It also helps in transportation of lipids around the cell and the creation of lysosomes.

LYSOSOMES Lysosomes are cellular organelles that contain acid hydrolase

enzymes that break down waste materials and cellular debris. They can be described as the stomach of the cell. Lysosomes digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria.

MITOCHONDRIA Mitochondria are a part of eukaryotic cells. The main job of

mitochondria is to perform cellular respiration. This means it takes in nutrients from the cell, breaks it down, and turns it into energy. This energy is then in turn used by the cell to carry out various functions.

PLASTIDS Plastids are the site of manufacture and storage of important

chemical compounds used by the cell. They often contain pigments used in photosynthesis, and the types of pigments present can change or determine the cell's color.

VACUOLES Vacuoles also play an important role in plant structure. Plants

use cell walls to provide support and surround cells. The size of that cell may still increase or decrease depending on how much water is present. Plant cells do not shrink because of changes in the amount of cytoplasm.