Cell: The Unit Of Life Flashcards
(21 cards)
What are the two types of organisms
1) Unicellular or Acellular
Eg: amoeba, diatoms, chlamydomonas,bacteria and many fungi like yeast etc
2) multicellular
Eg: plants, animals etc
What is cell?
Cell is a unit of structure and biological activity made of an organised mass of protoplasm surrounded by a protective and selectively permeable covering.
What is cytology?
The study of form, structure and contents of a cell as observed under a microscope.
Who coined the term cytology?
Hertwig (1893)
He also wrote a book on “ Cells and Tissues”
1)
Human body has some 260 types of cells and they are grouped into tissues
What is a tissue?
Tissue is a group of cells having common origin that performs specific function.
Who examined cells prior to Robert Hooke?
Jan Swammerdam(1658) Had seen red blood corpuscles of frog
Marcello Malpighi(1661) Observed small structure or utricles in slices of plant and animal tissues
Who discovered cell?
Robert Hooke(1665) From break of oak tree
The 4 organelles whose functions are coordinated in the EMsystem
1) endoplasmic reticulum
2) Golgi apparatus
3) lysosome
4) vacuoles
Endoplasmic reticulum was independently discovered by
Potter and Thomson
The term endoplasmic reticulum was given by
Potter
Occurrence of endoplasmic reticulum
Endoplasmic reticulum was developed in plasma cells, liver cells, pancreatic cells and interstitial cells( testis)
It is poorly developed in spermatocytes( sperm cells)
Completely absent in mature RBC
Origin of endoplasmic reticulum
Nuclear membrane
How is the structure if endoplasmic reticulum formed
From the outer nuclear membrane the endoplasmic reticulum is formed and moved into the cytoplasm and reaches till the plasma membrane
Major site if synthesis of lipid
Ribosomes are not attached in SER ( smooth endoplasmic reticulum) and it is a major site for synthesis of lipid
What are the components
1) cisternae : flattened sac like structures
2) tubules : small tube like structures can be branches or unbranched
3) vesicles : sac or disc like structures
About RER ( rough endoplasmic reticulum )
1) ribosomes are present which make the surface rough, they are like granules, so this is called granular ER or rough ER
2) cisternae and tubules are present
3) ribosome is attached to the membrane with the help of larger subunit
4) the place where ribosome gets attached one pore is formed
About SER( smooth endoplasmic reticulum )
1) They are agranular or smooth ER
2) tubules and vesicles are present
Origin of RER and SER
1) RER origin: nucleus ( internal)
2) SER origin: RER (peripheral )
Protein synthesis
Smaller and larger subunits of ribosomes are attached
Small subunits are freely present in cytoplasm
Increase in Mg concentration helps in joining of smaller subunits
Functions of RER
RER can synthesis
1) plasma membrane proteins
2) lysosomal proteins 3) secretary proteins
