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 are his morning and bedtime doses, a) Donald is a 50 year old male wit...

a) Donald is a 50 year old male with a long history of bipolar disorder. He has been hospitalized three times in the last 8 months for manic episodes. He was just admitted to your

Explain functional property of gelation/viscosity, Explain Functional prope...

Explain Functional property of Gelation/Viscosity  Mode of action  Protein-protein interactions produce matrix formations and setting Food system Salad dressings,

Light and distribution, Light and Distribution We have mentioned in the...

Light and Distribution We have mentioned in the beginning that the variation in the amount of light generally affects the global and local distribution of plants and animals. L

What are vectors of parasites, Q. What are vectors of parasites? The Ve...

Q. What are vectors of parasites? The Vectors of a parasite are organisms can transport the parasite during stages of its life cycle mediating the infection of other hosts. For

Classification of instrument sterilisation, The classification was given by...

The classification was given by Spaulding and is based on the contact with different tissue types to determine whether sterilization or disinfection is needed. 1. Critical item

Blood cells, BLOO D CORPUSCLES (= BLOOD CELLS) - Blood corpuscles are ...

BLOO D CORPUSCLES (= BLOOD CELLS) - Blood corpuscles are of the following three types: Erythrocytes, Leucocytes and Thrombocytes. (A )     Erythrocytes (Red Blood Corpusc

The physical environment - stress of hospitalization, The Physical Environm...

The Physical Environment   The actual hospital environment is another factor that may be stressful for the child and family. There are many unfamiliar sights, sounds and smells

Phases of karyokinesis, Phases of Karyokinesis: Karyokinesis can furth...

Phases of Karyokinesis: Karyokinesis can further be divided into prophase, metaphase, anaphase and telophase. 1-Prophase: (pro= before) Chromatin: During Interphase (non

Define intracellular fluid or the water within the cells, Define intracellu...

Define intracellular Fluid or the water within the cells? The intracellular Fluid or the water within the cells makes up about 40-4596 of the total body weight. Because the bod

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