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

What is deoxynivalenol, Q. What is Deoxynivalenol? Deoxynivalenol (DON)...

Q. What is Deoxynivalenol? Deoxynivalenol (DON) is a far more common, but much less toxic, trichothecene and is produced by species such as F. graminearum and F. culmorum. LD

Define flow phase in physiological response to injury, Define Flow Phase in...

Define Flow Phase in Physiological Response to injury? It is characterized by hyper metabolism, increased cardiac output, increased urinary nitrogen losses, altered glucose met

Describe prematurity in coronaw artery disease, Describe Prematurity in cor...

Describe Prematurity in coronaw artery disease ? CAD in Indians tends to be more aggressive and manifests at a younger age. Generally CAD occurring before the age of 55 years i

Horse diseases-borna disease, Borna disease Borna disease is fatal neurolo...

Borna disease Borna disease is fatal neurological disease of horses and sheep caused by a virus (RNA) of the family Bornaviridae and the disease is characterized by sub acute meni

Phylogenetic species concept, Q. Phylogenetic species concept ? Taxonom...

Q. Phylogenetic species concept ? Taxonomists (scientists who compare, classify and name organisms) tend to describe a species by studying their physical characteristics and be

Barriers to fertilisation, Barriers to Fertilisation Incompatibility c...

Barriers to Fertilisation Incompatibility can occur anywhere from pollination to syngamy and consequently obstructing fertilisation. The pollen fails to germinate or the polle

Adaptation, Adaptation Closely related to irritability is the capacit...

Adaptation Closely related to irritability is the capacity of living things for adaptation. You might have noticed that whenever you go outside in the bright sun after having

State the basic properties of cell, State the basic properties of Cell ...

State the basic properties of Cell The differences of cell types notwithstanding, the similarities among them are more profound. Actually, all cells possess the same basic prop

Mr, Define animals

Define animals

Cytokinesis, Cytokinesis It is defined  as the division or cleavage  of...

Cytokinesis It is defined  as the division or cleavage  of cytoplasmic  part   of the cells  into  two  daughter  cells. It is first  indicated   during  late  anaphase  by app

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