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

Is memory loss an early sign of alzheimer''s disease, Is memory loss an ear...

Is memory loss an early sign of Alzheimer's disease? A. Memory loss is one of the earliest symptoms of Alzheimer's disease and other kinds of dementia however occasional forget

Phylum protozoa, Classification of the phylum protozoa

Classification of the phylum protozoa

Define secondary level care - public nutrition, Define Secondary level care...

Define Secondary level care - public nutrition? More complex health problems of the community are resolved at the secondary level care through the district hospitals and the Co

Define biomaterial and an implant, Define biomaterial and an implant and st...

Define biomaterial and an implant and state their role in general Biomaterial : A pharmacologically inert material that is capable of interacting with a living organism witho

How inhibition might contribute to tumour formation, We now understand that...

We now understand that mutations that cause the inhibition of apoptosis are found in tumours. Because proliferation itself is not induced by the inhibition of apoptosis, explain ho

Explain the periodic table of the elements, Explain the periodic table of t...

Explain the periodic table of the elements ? Periodic Table of the Elements :  An element is a pure substance composed of atoms all of a single kind. It cannot be broken down

Explain mode of feeding, Normal 0 false false false EN-...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4 Mode of feeding

What are the use of a barrier membrane is grafting procedure, What are the ...

What are the uses of a barrier membrane is grafting procedures? Uses of barrier membrane in grafting procedures : i) Help in stabilizing the graft ii) Prevents ingrowth

Define procedure for testing presence of proteins in milk, Define Procedure...

Define Procedure for Testing the Presence of Proteins in Milk? 1. Add 0.5 ml of alcohol to 0.5 ml milk.  Alcohol helps in curdling the milk. 2. Observe for the curdling of m

What is deplasmolysis of plant cells, What is deplasmolysis of plant cells?...

What is deplasmolysis of plant cells? The plant cell when placed under hypertonic medium loses a huge amount of water and its cell membrane detaches from the cell wall. In that

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