Large organism β not have large-sized cells but more cells
Structural unit
Functional Unit
Building blocks
Smallest unit capable of independent existence
Totipotent: Single cell can form whole organism
Cell Tissue Organ Organ System (division of labour)
Pasteur β life originates from life
Haeckel β nucleus stores and transmits hereditary
1st by Zacharias Janssen β 1590
Modified by Galileo
Then by Robert Hooke β new microscope β study of cork cells
Hooke β book β Micrographia- honey comb structure called it cellula
Malphighi β called it saccules & utricles
Leeuwenhoek β 1st to observe, describe & sketch free living cell
Robert Brown β disc. nucleus in cell
Dujardin β living semifluid substance as sarcode
Purkinje & von Mohl β called sarcode as protoplasm
Schwann β disc. cell membrane
Nageli & Cramer β named it as cell membrane
By Schleiden & Schwann
Schwann β animal cells donβt have cell wall
Organism made of cells
Cells are units of structure and function of living organisms
New cells from pre-existing cells
Each cell has protoplasm
All cells are alike in chemistry & physiology
Activity of organism are sum total of activities of cell
All living beings have cells
Cells are units of structure & function
Cell can survive independently, organelle cannot
Cells have fundamental similarity
Life exists in cells
Cells can be modified (elongated in muscle & nerve cell)
Cell grows & multiplies
Life passes to next generation as cell
New cells from pre-existing cells
All cells have common ancestry
Cells are totipotent
No organism can have activity that is absent in its cell
Virus are a cellular
Some organisms β body is not differentiated in cells (e.g. rhizopus)
Protozoa have uninucleate differentiated body
Bacteria & cyanobacteria donβt have nucleus
RBCs & sieve tube cells are without nucleus
In skin & cork β protoplasm is replaced by nonliving material
Small cells β higher surface volume ratio
Surface Volume Ratio of Image - 1 for Cell Introduction
Surface Volume Ratio of Image - 2 for Cell Introduction
Surface Volume Ratio of Image - 3 for Cell Introduction
Undifferentiated / Stem Cells: Unspecialized and have power of division β stem apical meristem
Differentiated / Post-mitotic Cells: Specialized for better organization and avoid duplication
Dedifferentiated Cells: Differentiated cell which revert to undifferentiated state and loose specialization - cork cambium of plant, healing of wound, regeneration in animals and vegetative propagation in plants
Separation from extracellular medium
Selective permeability
Accumulation
Interconnections
Recognition
Communication & exchange
Intracellular compartmentalization
Smallest cell β Mycoplasma
RBC is 7 in diameter
Lymphocytes are 6
Kidney, liver and intestine are 20-30
Longest human cell β nerve cell of 90 cm
Egg cells are large sized cells β store food for embryo
Avian eggs are largest
Surface cells β flat
Cortex β polygonal
RBC β biconcave
Nerve cells β long
Sperms β tail for mobility
Prokaryotic & eukaryotic cells (to be discussed in next lesson)
-Manishika