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

Biological adaptation, Biological Adaptation These adaptations depend ...

Biological Adaptation These adaptations depend on the geology and basic fertility of the region and some of the mechanisms that are especially well developed in tropical rain

Explain adverse effects of oseltamivir, Explain Adverse Effects of Oseltami...

Explain Adverse Effects of Oseltamivir  Nausea and vomiting can occur. Taking the drug with food decreases the incidence of nausea. In juvenile rats, very high doses of osel

Ventilation of tracheal system - diffusion, Ventilation of Tracheal System ...

Ventilation of Tracheal System - Diffusion Gaseous exchange due to diffusion generally takes care of the oxygen needs of most small insects. Similarly fairly large but inactiv

Mechanism of enzyme action, Mechanism  of Enzyme Action  The action of...

Mechanism  of Enzyme Action  The action of enzymes is to lower  the activation energy  or threshold  of their substrates which. Therefore  become  activated and   react  with

Explain the concentration of a solution, Explain The concentration of a sol...

Explain The concentration of a solution The concentration of a solution is the amount of solute dissolved in a specified amount of solvent or solution.  When the concentration

Calculate micronutrient and other nutrient requirements, Calculate Micronut...

Calculate Micronutrient and other specific nutrient requirements? The recommended average daily per capita intake of various specific nutrients for typical population requiring

How would you confirm this disease, Question 1 A patient is admitted to th...

Question 1 A patient is admitted to the hospital with suspected pulmonary tuberculosis. How would you confirm this disease? Answer the following questions                   a)

Gel electrophoresis, If child has same gel positioning as father, would it ...

If child has same gel positioning as father, would it be likely for the child to get cancer if the father has it? For the children without the mutation, what is the risk of getting

Describe how the various molecular mechanisms act, 1. Using specific exampl...

1. Using specific examples describe how variations in DNA sequence between individuals can lead to risk of disease. Describe how a range of techniques have been adapted to detect s

Cardiac cycle, Cardiac Cycle Cardiac cycle has two phases-systole and...

Cardiac Cycle Cardiac cycle has two phases-systole and diastole. Ventricular systole and diastole occur as a result of depolarization and chamber volume and pressure. The di

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