Definition of Cell
The cell is defined
as it is the structural and functional unit of life. It is responsible to carry
out all the activities of life.
It is a
small piece of cytoplasm that contains a nucleus and is covered by an outer
protective layer. The cell membrane.
Types of
Cell
Cells are an
important part of all activities of life, and are divided into two types: prokaryotic cells and eukaryotic cells. The cell was
discovered by Robert Hook. The nucleus was studied by Robert Brown.
Prokaryotic
Cells
·
There
is no nucleus in prokaryotic cells. Instead, some prokaryotes (such as
bacteria) have an area within the cell where genetic material is freely
suspended. This area is called nucleoid.
·
They
are all single-celled microorganisms. Examples include archaea, bacteria and
cyanobacteria.
·
The
cell size range from 0.1 to 0.5 µm in diameter.
·
In
prokaryotic cell the genetic material can be DNA or RNA.
Eukaryotic
Cells
·
The
characteristic of eukaryotic cells is the true nucleus.
·
The
cell size range from 10–100 µm in diameter.
·
This
category includes plants, fungi, protozoa, and animals.
·
The
plasmaa membrane is responsible for monitoring the transport of nutrients and
electrolytes in and out of the cell. It is also responsible for cell-to-cell
communication.
·
They
reproduce sexually and asexually.
· There are some contrasting characteristics between plant cells and animal cells. E.g.
Structure
of Cell
When a group
of cells are joined together, it will form different tissues, and different
tissues will form the organs that ultimately form our entire body. The
structure of cells can be studied with optical or electron microscopy.
Different parts of the cell can be separated by a technique called cell
fraction.
Components of Cell
There are three major
components of a cell i.e.
·
Nucleus
·
Cytoplasm
·
Cell
Membrane
Nucleus
The nucleus is a sphere composed of many organelles such as nucleoli. Most of the genetic material of the cell exists in the nucleus in the form of linear DNA molecules. These molecules have organized structures called chromosomes. The main function of the nucleus is to control many functions of the cell.
It is surrounded by a nuclear membrane and is also a place
for DNA/RNA synthesis. Chromatin is present in the nucleus of the DNA-protein
complex. The chromatin of the cell nucleus condenses during cell division.
Cytoplasm
The cytoplasm is not the nucleus, but the jelly-like
substance that exists outside the nucleus. Organelles are located in the
cytoplasm. Like many enzymes used for normal metabolism, various metabolic
events occur, and protein synthesis also exists in the cytoplasm. Some fibers
of the cytoskeleton system are also included to organize the cytoplasmic
structure.
Cell
Membrane
The cell membrane or plasma membrane is a thin layer of protein and fat that surrounds every living cell. It is a semi-permeable membrane that allows certain types of substances to enter and prevents others from entering the cell. The main components of the plasma membrane are highly charged carbohydrates, proteins and nucleic acid molecules. In addition, it separates the cell from the internal or external environment.
The basic characteristics of cells:
·
Cells provide structure and support for the
organism's body.
·
The inside of the cell is organized into independent
single organelles, surrounded by different membranes.
·
The nucleus (the main organ) has the genetic information
needed for reproduction and cell growth.
·
Each cell in the cytoplasm is composed of a nucleus
and a membrane-bound organelle.
·
Mitochondria are a double-membrane-combined
organelle, which is mainly responsible for energy transactions that are important
for cell survival.
·
Lysosomes digest unwanted substances in cells.
·
The endoplasmic reticulum plays an important role in
the internal organization of cells by synthesizing and processing selective
molecules, guiding and sorting them to appropriate positions.
Post a Comment