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

Are there non-parasitic viruses, Q Are there non-parasitic viruses? All...

Q Are there non-parasitic viruses? All viruses are necessitating intracellular parasites that are they depend on the host cell to complete their life cycle. A virus does not ha

Describe the lymphatic organs in human biology, Describe the Lymphatic Orga...

Describe the Lymphatic Organs in human biology? The lymphatic organs include the lymph nodes, the spleen, the thymus gland, the tonsils, and Peyer's patches, all containing lym

What would happen to the neuron, If neurons are exposed to a chemical agent...

If neurons are exposed to a chemical agent that prevents the NA+ channels from opening, what would happen to the neuron? What would happen if the K+ channels were inhibited? What d

What is the role of linked traits in genetics, What is the role of Linked T...

What is the role of Linked Traits in genetics? In his study of inheritance in the fruit fly, Morgan observed that certain genes are distributed together, or linked, rather than

Dfine digestion, Dfine Digestion, Absorption and Transport of proteins? ...

Dfine Digestion, Absorption and Transport of proteins? Under this sub-section, we shall learn how proteins that we consume are digested, absorbed and transported to various bod

How is the extracorporeal digestion, Q. How is the extracorporeal digestion...

Q. How is the extracorporeal digestion associated to predation in arachnids? Arachnids can inoculate poison to kill or paralyze their preys using structures called chelicerae.

Indications for surgery-tricuspid valve disease, Indications for Surgery : ...

Indications for Surgery : Echocardiography or right heart catheterization can quantify tricuspid stenosis. It is categorized as Tricuspid valve repair is advised when ther

Classifications of carbohydrates based on number of carbon, Define the Clas...

Define the Classifications of carbohydrates based on number of carbon?   A chain-form monosaccharide that has a carbonyl group (C= O) on an end carbon forming an aldehy

Mollusca, locomotary organ in mollusca

locomotary organ in mollusca

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