Cell theory, Biology

Assignment Help:

Cell Theory

The invention  of  the  compound microscope  in  the 17th century stimulated the  interest in living things not  visible  to  the  naked  eyes. Thus, Robert Hooke discovered  'cells'  in 1665 by  examining cork  slices  (,under  a crude microscope. He was  actually describing  the spaces occupied by  the cells  limited by  the cellulose walls. Hooke and his contemporaries also described cells from other plants  and  animals.

 

1299_Cell Theory.png

Figure: A generalized plant (a) and animal (b) cell. No one cell of either plant (a) or animal (b) has all the characteristics shorn in these composite figures. Both these are

 

However, cell theory, one of  the  greatest  and most basic generalizations of  biology, was formulated only  about 200 years later. Two German  investigators, Schleiden a botanist (1838), and Schwann, a zoologist  (1839) are credited with  presenting  independently the first concise, yet  comprehensive, statements about the cell. They  pointed out  that, "All plants and. animals are made up of  small fundamental units called cells and that some organisms are unicellular and others, multicellular." Subsequent researched  to the expansion of  this concept by  including further information on  cells. We  know that cells are surrounded by  cell membrane and contain cytoplasm and  nucleus and, most importantly, cells divide into  roughly  equal daughter cells by  a process called  cell division. Thus it became known  that new  cells come into existence only by the division of  previously  existing cells.  In  other words,  cells do not  arise by spontaneous generation  from  nonliving matter. It  follows that all cells living  today  can trace their ancestry back  to those which  existed  in  ancient times.

 


Related Discussions:- Cell theory

Aleurone grains, ALEURONE GRAINS - Also known as Plant lysosome , beca...

ALEURONE GRAINS - Also known as Plant lysosome , because they contain hydrolytic enzymes. Consists of Proteins. They are also known as Aleuroplast because they are ric

Nonshivering thermogenesis, Normal 0 false false false ...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

What are lateral meristems, What are lateral meristems? Where can they be f...

What are lateral meristems? Where can they be found and which type of plant growth do they promote? Lateral, or secondary, meristems, are the cambium and the phellogen (also ca

Expalain briefly vitamin A, Vitamin A (Retinol) Purified vitamin A is a...

Vitamin A (Retinol) Purified vitamin A is a viscous yellowish oil. It is freely soluble in most organic solvents such as methanol, ether, acetone, chloroform and petroleum ethe

Explain protein stabilized food emulsions, Protein Stabilized Food Emulsion...

Protein Stabilized Food Emulsions Many food products are emulsions (eg. milk cream, ice creams, cream, butter etc.) and protein constituents often play a major role in the stab

10 mcq question of plants, 10 mcq question in the topic of plants of 9th st...

10 mcq question in the topic of plants of 9th standard

Drawbacks of lamellar model, Drawbacks of Lamellar model This model ...

Drawbacks of Lamellar model This model does not explain the elasticity of PM. Although this model says that PM is elastic but it also states that head of lipid molecules is

Environment , Environment All organisms are intimately dependent on the ...

Environment All organisms are intimately dependent on the environment from which they derive their sustenance. Organisms from virus to man are obligatorily dependent on the envi

Pre pregnancy counselling, Pre Pregnancy Counselling To prevent excess...

Pre Pregnancy Counselling To prevent excess spontaneous abortions and congenital malformations in infants of diabetic mothers, diabetic care, education and counselling must be

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd