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 the role of the nad molecule in glycolysis?, What is NAD? What is t...

What is NAD? What is the role of the NAD molecule in glycolysis? NAD (nicotinamide adenine dinucleotide) is a hydrogen acceptor essential as reductant (to receive hydrogen) in

Define the bacillus cereus, Define the Bacillus cereus Bacillus cereus ...

Define the Bacillus cereus Bacillus cereus is not a common cause of food poisoning. It is a Gram positive, aerobic, spore forming rod shaped bacteria normally present in soil,

Explain the mortality and survivorship curves, Explain the Mortality and Su...

Explain the Mortality and Survivorship Curves? Mortality : Just as a population has a birth rate, so does it have a death rate. A populations rate of death, or the number of

What is the goal of risk assessment, What  is  the  goal  of  risk ass...

What  is  the  goal  of  risk assessment? The goal of risk assessment is to provide risk managers, who might be, for example, government regulatory officials, industry health a

Define role of nutrients in controlling gene expression, Define Role of Nut...

Define Role of Nutrients in Controlling Gene Expression? The role of several nutrients in controlling gene expression, as mentioned earlier, is in infancy, but with advancing b

Can you explain balloon valvuloplasty, Q. Can you explain Balloon Valvulopl...

Q. Can you explain Balloon Valvuloplasty? Whenever feasible valvuloplasty is the treatment modality of choice. One has to make sure that the valve is suitable and expertise to

Describe lifetime risk estimation, Describe Lifetime Risk Estimation ? ...

Describe Lifetime Risk Estimation ? Traditional statistical and epidemiological methods of estimating long-term risks do not accurately reflect population burden of disease. Th

Symptoms of hiatus hernia, Q. Symptoms of hiatus hernia? In most patien...

Q. Symptoms of hiatus hernia? In most patients, no symptoms are seen. When symptoms do occur, they are: 1. discomfort after heavy meal, 2. Difficulty in breathing while l

Embryology and histology, Embryology: Embryology (from Greek words embryon...

Embryology: Embryology (from Greek words embryon which means unborn embryo and logia which means study) is a branch of science which deals with the development of an embryo starti

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