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

Stable atoms have no vacancies in their outer shell, Select all that are tr...

Select all that are true/correct: Stable atoms have no vacancies in their outer shell. Hydrogen is more stable than carbon Helium is more stable than carbon Helium is more stable t

State the purposes of dressing, PURPOSES OF DRESSING A dressing can hav...

PURPOSES OF DRESSING A dressing can have a number of purposes, depending on the type, severity and position of the wound, although all purposes are focused towards promoting re

Agro industrial-nutritive value of crop residues, Nutritive value of crop r...

Nutritive value of crop residues Nutritive value is generally determined by feed composition, intake and utilization  efficiency of digested matter. Thus, the value of a feed

Pathophysiology, Case scenario Mr Kit Lee, a 28-year-old unrestrained dr...

Case scenario Mr Kit Lee, a 28-year-old unrestrained driver of a utility, was travelling on a highway at 100kph and swerved to miss road debris. He lost control and struck a tre

Define management & prognosis of root perforation, Define Factors Affect Ma...

Define Factors Affect Management and Prognosis of Root Perforation Time Location of defect in relation of crestal bone Level of perforation Size Periodo

Feeding on food masses, Normal 0 false false false EN-I...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

What is the process of protein synthesis, Q. After the fact that it is base...

Q. After the fact that it is based on information from mRNA what is the process of protein synthesis called? Protein synthesis is called translation of genetic information into

What are pleura, What are pleura, pericardium and peritoneum? Pleura ar...

What are pleura, pericardium and peritoneum? Pleura are the membrane that hides the lungs and the inner wall of the chest; pericardium is the membrane that hides the heart; per

Explain the buccal perforations, Buccal Perforations Buccal concavitie...

Buccal Perforations Buccal concavities in the bone can result in some threads of the implant being exposed. Where these are very circumscribed and covered with thick and well-

Explain the main steps in the mongoose bioassay, Question : Explain the...

Question : Explain the main steps in the mongoose bioassay and the mouse bioassay as conducted for testing ciguatera in Mauritius? (i) Provide a brief description on the beh

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