All living things are composed of small units that cannot be seen with the naked eye. These units are referred to as cells. Some organisms consist of just one cell(unicellular), while others are made of several cells(multicellular).
WHAT IS A CELL?
A cell defined as the building block of all living organisms
It is the smallest unit of life that carries out all of life method/process.
FORMS WHICH LIVING CELLS EXIST
living cells exist as:
1) Independent organisms (unicellular organisms) which includes bacterias, protozoa, many algae and some fungi.
A colony is a group of cells held together by mucilage and they move together as a unit e.g. Volvox, Eudora etc.
living cells also exist as a filament, example spirogyra.
Cell was first discovered with a microscope by “Robert Hooke” an English Scientist in 1665. He reported that tissues were made up of box-like structures or compartments that he called cells.
In 1839, German biologists, Theodor Schwann and Matthias Schleiden carried out more research about cell in a book. His report was thus “All organisms are composed of essentially alike parts, called the cells”.
THE CELL THEORY.
(ideas that make up the cell theory)
1)All living can perform life processes. Cells are the basic unit of life.
2)All cells come from pre-existing cells.
Animal cells are the fundamental unit of life in the animal kingdom.
Plant cells are the fundamental unit of life in the kingdom plantae.
CLASSIFICATION OF PLANT CELLS.
Plant cells can be classified into three types.
The Parenchyma cells help in storage, photosynthesis and other functions.
The Collenchyma cells are only present during maturity and have only a primary wall.
The sclerenchyma cells help in mechanical support.
Plant cells turn carbon dioxide into sugar, and animal cell break the sugar down to carbon dioxide to make energy.
DIFFERENCES BETWEEN ANIMAL AND PLANT CELL.
1)Presence of chloroplast in plants and absence of chloroplast in animals cells.
2)Animal cells do not have rigid cell walls like plant cells.
3)Plant cell walls are made of cellulose, this allows high pressure to build up in plant cells without the cells bursting.
4)Presence of a large vacuole in plant cell. and small vacuoles in animal cells.
Similarities In Plant And Animal Cell.
1)Both plant and animal cells are eukaryotic, which means they have a defined nucleus which contains chromosomes.
2)Animal and plant cells have a cell membrane that surrounds the cell.
3) Both cells have complex structures.
4)Both plant and animal cells have plasma membranes.
CELL STRUCTURE AND FUNCTIONS.
Plant and animal cells contain organelles which are tiny structures inside a cell that performs specific functions for a cell. Example: lysosome and chloroplast.
1) Mitochondrion (pl: Mitochondria):
– An energy source
-Site of cellular respiration
-Presence of two membranes (inner and outer membranes)
-Spherical/rod shaped organelles
2) Nucleus (pl:Nuclei):
– Contains the genetic material
– Seperates the genetic materials
– Spherical structure within the nucleus
– Consists of DNA and RNA
– The fluid present in the nucleus
– It is highly viscous
– Thread like structures that consists of genetic materials
– Carry genetic information in it’s DNA
– Small dot like organelles
– Involved in protein synthesis
– Smallest cellular organelles
7) Endoplasmic Reticulum (ER):
– Connected to the nuclear membrane
– Synthesis proteins, steroids and lipids
-Exists as smooth and rough ER
– Collects, stores and distributes proteins, steroids and lipids.
– Also called cell membrane
– It is a protective and selective outer barrier
9)Golgi Apparatus/ Golgi Body:
– Bounds sacs
– Transports and stores lipids
– Changes protein into glycoproteins
– Stores water, enzymes, nutrients, salts and dissolved gases
– Provides support, shape and protects the cell organelles
– Removes undigested materials
– Releases enzymes to digest external materials
– They are paired cylindrical organelles
– They migrate to the opposite poles of the cell during cell division
– Bound by a single membrane
– Filled with cell sap
14) Cell wall
– Protects and supports the cell
– Maintains the shape
– Carry out photosynthesis in the chlorophyl
– Stores food and pigments.
Now you have gain a whole new knowledge not just about the human body cells but that of animals and plants as well, let us know your thoughts in the comment section.