Cell the unit of life class 11 neet (Part-1 by UK sir)
Cell the Unit of life
- C e l l -
Defination:
•
Structural and functional
unit of life.
•
Cell must have independent
existence.
•
Can able to
perform all essential functions of life.
•
Cell is a mass of
protoplast covered by a semipermeable membrane and can perform all life
activity.
•
Cell is an open
system.
If you want to know about life:
Go to this link:
Type-of-cell
History :
•
Robert Hooke
(1665) : coined the term cellulae , in the Book Micrographia, Observe dead cell
in Oak tree cork
•
Anton VonLeeuwenhoek (1674) : discover Living Cell in protozoan cell in pond water,
tartar of teeth, RBC in blood etc
•
Robert Brown1831: discover Nucleus in root cell of Orchids.
•
J .E. Purkinjee
1839: coined term protoplasm
•
Huxley (1868):
termed “Protoplasm is the Physical basis of Life”
•
Mathias Schleiden
and Theodor Schwann 1839 : Formulated
Cell Theory.
•
Rudolf Virchow 1855: Proposed – “Omnis Cellula e
Cellula”
Cell Theory: By Schleiden & Schwann (1839):
•
All living
Organism made up of Cell and their product.
•
Cell –small mass
of protoplasm, nucleus, plasma membrane and may or may not with cell wall.
•
All cells are
same basically in their chemistry and physiology.
•
The activity of
organism is sum total activity of all cells.
•
All cells
developed from their pre existing cells.
Modern cell theory: (Cell doctrine or Cell Principle)
•
Body of all
living organism made by cell or cells or their products.
•
Cells are
structural units of life.
•
Cells are
functional units of living organism.
•
Cells can survive
independently but Organelles can’t.
•
All cells of one
organism have a fundamental similarity in structure, chemical composition and
metabolism.
•
All Life activity
is performed by cell.
•
Cells may get
modified according to their function.
•
Multiplication of
cell leads to Growth of an organism or reproduction.
•
Genetic
information stored and expressed inside cell.
•
Life transform
from one generation to another in the form of a living cell.
•
New cell must
arise from its preexisting cell.
•
Cells are
totipotent unless they become specialized.
Size of Cell :
*
Cells are of Variabe
size.
*
Mycoplasma(PPLO)
Smallest: 0.1-0.5 micrometer(µm)
*
Bacteria - 3-5
µm
*
Multicellular
Eukaryotes - 5-100 µm
*
Human RBC -7 µm
*
Muscle cell - 1-40
mm long and 30-80 µm wide
*
Nerve cell - upto
90 cm
*
Plant fiber cell
like Cotton- 4cm, Jute - 30-90 cm
*
Eggs are
largest.
*
Hen Egg - 60/45
mm
*
Ostrich Egg
170/150 mm
 |
| cell-size |
 |
| Shape-of-cell |
*
Cells are of
variable shaped.
*
Disc like,
polygonal, columnar, thread like , amoeboid, cuboid, irregular etc
*
Ex- Polygonal
cell can be seen in plants, Fiber cell of plants are thread like, epithelial
cells are Column like etc.
Types: on the basis of Division
*
According to
division power they are of 3 types:
1.
Un
differentiated (stem cells):
- with
power of division or totipotency.
-In
plants they can be meristematic cells present in root tip, shoot tip, cambium
etc.
-In Human
example of stem cell is bone marrow cells.
2. Differenciated or Post Mitotic Cells:
- specialized to perform specific functions. Change in
shape and size and further don’t divide.
3.De-Differentiated cell:
-Loose their specialization and again start divide
e.g.- Cork cambium. They gain the power
of Division.
If you want to know about life:
Go to this link:
https://lifemeaning7.blogspot.com/2018/02/what-is-life.html
" Feel Free to ask in Comment session, I will answer. ... UK Sir "
Nice notes sirji...
ReplyDeleteThank you.. stay connected.
Delete