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

Define the sleep disorder - effect of obesity, Define the Sleep disorder - ...

Define the Sleep disorder - Effect of Obesity? One of the common problems that obese males and females suffer from is sleep disorder, commonly known as sleep apnoea. Obesity ca

Which term describes organisms which live in lake/ocean, Which term is used...

Which term is used to describe organisms that live on or in the bottom of an ocean or lake. Such organisms can be found anywhere from the shoreline to greatest ocean depths? a)

Define alcoholic cardiomyopathy, Q. Define Alcoholic Cardiomyopathy? In...

Q. Define Alcoholic Cardiomyopathy? In a case of dilated cardiomyopathy alcohol cardiomyopathy is suspected if there is history of alcohol intake of 100g/day for more than 10

Can obesity causes the cardiovascular disease, Q. Can Obesity causes the ca...

Q. Can Obesity causes the cardiovascular disease? Obesity is established as a leading predictor of CAD and is associated with several cardiovascular risk factors like cholester

Conventional agro-industrial oilseed cakes, Conventional agro-industrial oi...

Conventional agro-industrial oilseed cakes Groundnut meal: It is readily available protein source byproduct from the extraction of groundnut, which is a popular human food i

Breifly describe the menstrual cycle, Breifly describe the Menstrual Cycle?...

Breifly describe the Menstrual Cycle? Each month during a female's reproductive years, the hypothalamus secretes a hormone that stimulates the anterior lobe of the pituitary gl

Determine the foos sources of cyanocobalamin, Determine the Foos Sources of...

Determine the Foos Sources of cyanocobalamin? Vitamin B I2 is unique among vitamins in the sense that it is mostly found in foods of animal origin but is not generally present

Explain progressive loss of the axonal myelin sheath, What are some disease...

What are some diseases characterized by progressive loss of the axonal myelin sheath? Multiple sclerosis is a severe disease caused by progressive destruction of the myelin she

What are ions, What are ions? What are the two types of molecules into whic...

What are ions? What are the two types of molecules into which ions are classified? Ions are atoms or substances electrically charged by means of loss or gain of electrons.

What are the three main limiting factors of photosynthesis, What are the th...

What are the three main limiting factors of photosynthesis? The three major limiting factors of photosynthesis process are light intensity, carbon dioxide concentration and tem

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