Cell is the basic organizational unit of life. All cells belong to two basic types: the prokaryotic cells and the eukaryotic cells. Such a classification is based on the absence and presence of a nuclear membrane.
In this type of cells nuclear material is dis persed into cytoplasm; it means nuclear membrane is absent around nuclear material. Usually definite organelles such as golgi bodies, centrosomes, mitochondria, chromosomes etc. are absent.
General character of prokaryotic cells:-
- Nucleus and nuclear membrane are absent in prokaryotic cells.
- Histone protein lacking in DNA / DNA is naked.
- Plasma membrane is very simple is structure and Composition. It carries out the functions of other cellular organelles.
- Genetic material present in the cytoplasm.
- Cell division does not involve a nucleare spindle, So it is a mitotic.
- single circular chromosome present in the cytoplasm.
- There are mitochondria is absent. Respiratory photosynthetic enzymes are present in plasma membrane.
- There are endoplasmic reticulum is absent in prokaryotic cell.
- There are 70s type/Size ribosomes present and made up of 50s and 30s: Sub-units. All ribosomes are free in cytoplasm.
- chloroplast is absent in prokaryotic cell. How ever, present in blue-green algae is associated with lamellae. These lamellae are not enclosed by membrane.
- In prokaryotic cell Golgi bodies are absent.
- In prokaryotic cell Lysosome is absent.
- There are call-wall is thin, Non- cellulosic, contains amino sugars and muramic acid.
- Extra-nuclear material on pieces of ANA (plasmids) present in cytoplasm.
- m-RNA polycistronic.
- In prokaryotic cell, cytoplasmic streaming of Amoeboid movement does not occur .
- Cell division of prokaryotic is amitosis or direct.
- chlorophyll (when present) is not packed into chloroplast.
- Sexual reproduction is very rare.
- Ribosomes usually occur in polysome condition.
Nucleoid central region of the cell that contains it’s DNA.
It has provided structure & protection from the outside environment. These are most bacteria have a rigid cell wall made from carbohydrates and proteins called peptidolycans.
Ribosomes are responsible for protein synthesis.
There are every prokaryotic has a cell membranes also known as the plasma membrane, that separates the cell from the outside environment.
The fimbriae are thin, hair -like structures that help with cellular attachment.
Many bacteria have a layer of carbohydrates that surrounds the cell wall celled that capsule. It help to the bacterium attached to the surfaces.
Cytoplasm is the region of the cell between the nuclear envelop and plasma membrane.
There are pili rod-shaped structure involved in multiple roles; including attachment and DNA transfer.
The flagella are thin, tail -like structure that assist in movement.
The plasmid is a is a small, circular
Ex:- Bacteria, Archaea .
Nuclear membrane and well organised nucleus are present in this type of cells. Well organised cell or general such as golgi bodies, mitochondria, plastids, endo plasmic reticulum, centrosomes and chromosomes are present in this type of cells. Eukaryotic cells are present in the high groups of animals and plants.
Characters of Eukaryotic cells:-
- presence of a distinct nucleus and nuclear membrane.
- Many number of chromosome are present in Eukaryotic cell.
- DNA is tightly bound to histone protein to form nucleoprotein.
- The mitochondria is present in cytoplasm in eukaryotic cell.
- In eukaryotic cell Endoplasmic reticulum is present.
- Ribosomes -80s type/ size. In plants these dissociate into 60s and 40s Sub-units Most of the ribosomes attached to endoplasmic reticulum. There are some ribosomes are free in the cytoplasm.
- Structurally complex plasma membrane with distinct function .
- Genetic material lie inside the nucleus.
- Nuclear Spindle is formed during cell division.
- All green plants have chloroplast ; which have grana.
- In eukaryote cells;there are golgibodies present.
- In eukaryotic cells; there lysosome are present.
- In eukaryotic cells, there cell-wall is thick. Cellulose, doesn’t contain amino & muramic acid.
- Cytoplasmic streaming of Amoeboid movement may occur in eukaryotic cells.
- m-RNA usually monocistronic.
- Chlorophyll when present are packed into chloroplast.
- Sexual reproduction is common.
- Ribosomes occur as monosomes, on the surface of endoplasmic reticulum.
Nucleus store the genetic information in chromatin form.
It is differently permeable membrane through which extracellular substance may be selectively sampled and cell products may be liberated.
The nucleolus is the part of eukaryotic cells. Where ribosomal RNA in produced.
Mitochondria generally know as the power house of the cell, it has responsible for energy production.
Between cell wall and vacuole except nucleus, fluid present in the cell is called cytoplasm.
These are the site synthesis of proteins molecules.
Cytoskeleton or Cell wall:-
Cytoskeleton or cell wall provides structure, the cell movement and plays a role in cell division.
The cytosol is a gel like substance with in the cells that contains the organelles.
The endoplasmic reticulum is dedicated to protein maturation and transportation.
Vesicles & vacuoles:-
They are storage depots for excess water waste products, soluble pigments etc.
Ex:- plant, Animals, algae, fungi & protozoans.