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

Characteristic of ecotone, Characteristic of Ecotone A general charact...

Characteristic of Ecotone A general characteristic of ecotone is that it has sufficiently greater number of species and the diversity of most of the species at times is higher

Prepare a dichotomous key, Prepare a dichotomous key the following organism...

Prepare a dichotomous key the following organisms, ant, butterfly, fly, beetle, grass hopper, wasp, ladybug, roach and dragonfly

What are the constituent elements of the blood, What are the constituent el...

What are the constituent elements of the blood? The blood is made of a liquid and a cellular part. The fluid part is known as plasma and in it there are several substances, suc

What is the gross primary production of an ecosystem, Q. What is the gross ...

Q. What is the gross primary production of an ecosystem? How does GPP relate to photosynthesis? The Gross primary production of a GPP or ecosystem is the quantity of organic ma

Following statement true for prokaryotic or eukaryotic, Following statement...

Following statement true for prokaryotic or eukaryotic? They use deoxyribonucleic acid as their major information storage molecule

Define types of indicators, Define Types of Indicators? Macro indicator...

Define Types of Indicators? Macro indicators are used at strategic levels while micro indicators are used at performance levels. From the previous sections it is clear that man

Xenotransplantation, X e n o t r a n s p l a n t a t i o ...

X e n o t r a n s p l a n t a t i o n Over the past 20 years transplantation of heart and kidney has become almost a routine in human but the availability of

Explain that a peptide bond a covalent, Is a peptide bond a covalent or a n...

Is a peptide bond a covalent or a non-covalent bond? Please explain.

Final common pathway of the degradation of organic compounds, Q. Why is the...

Q. Why is the Krebs cycle also called the final common pathway of the degradation of organic compounds? The Krebs cycle is known as the final common pathway of the degradation

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