Unified cell theory, Biology

Assignment Help:

Unified Cell Theory

The present unified cell theory states that

  1. All living things are composed of either a single Cell or of the cells and cell products. The cell is a mass of protoplasm limited by a cell membrane, and possessing a nucleus;
  2. New cells are formed only by division of pre-existing cells;
  3. There are fundamental similarities in the chemical constituents and metabolic activities of all cells;
  4. The activity of an organism as a whole can be understood as the collective activities and interaction of its interdependent cellular units.

In view of this present cell theory the living organisms may be broadly divided into:

  • Acellular forms with body not composed of cells, for example viruses. 
  • Cellular forms with body composed of cells.

The cellular forms may further be classified into:

a) Unicellular organisms with only one cell in their body, for example bacteria. blue-green algae, protozoans, etc. and
b) Multicellular organisms having many cells in their body. In such forms the cells organise themselves into tissues, tissues into organs and organs into organ systems. Examples of these are animals ranging from sponges to man and plants ranging from most algae to all flowering plants.

1295_Unified Cell Theory.png

Figure: Some unicellular organisms: (a) Bacterium (Escherichia coli), (b) Blue green alga,(c) Mycoplasma, (d) Amoeba (a protozoan), (e) Chhydomonus (an alga), and (f) Mucor (a fungus)


Related Discussions:- Unified cell theory

Explain the process of metastasis, Explain the process of metastasis. Defin...

Explain the process of metastasis. Define anti-angiogenic drugs and relate the role of medical imaging, if any, in anti-angiogenic drug therapy. State how you envision your particu

Define x-ray chest and coronary angiography, Q. Define X-Ray Chest and Coro...

Q. Define X-Ray Chest and Coronary Angiography? X-Ray Chest It shows cardiomegaly with left ventricle (LV) and left atrium (LA) enlargement. There may be signs of pulmona

Dna replication at biochemical level, Although there is much talk in the ne...

Although there is much talk in the news about stem cell research, the public and policymakers need to understand how basic body cells work to transmit information and replicate to

Determine about the visual axes of eyes, Determine about the visual axes of...

Determine about the visual axes of eyes In normal eyes, the visual axes are parallel to each other in the primary position of gaze. This position is usually maintained but in t

What is the criterion used to classify hosts, What is the criterion used to...

What is the criterion used to classify hosts as intermediate hosts or as definitive hosts? The criterion used to classify hosts as intermediate hosts or as definitive hosts is

File & chemical removal of gutta percha-endodontics, File  & chemical remov...

File  & chemical removal of gutta percha: -    K-type file & chloroform is the best choice in small and curved canals. -    The pulp chamber floated with chloroform, then k-typ

Define intentional adulteration - types of adulteration, Define Intentional...

Define Intentional Adulteration - Types of Adulteration? In intentional adulteration, the substance is added, removed or substitute knowingly by the adulterator for the purpose

Which are the structures that are part of the nervous system, Which are the...

Which are the structures that are part of the nervous system? The structures that form the nervous system can be separated into the central nervous system (CNS) and the periphe

Explain the frank furcal perforation, Explain the Frank Furcal Perforation ...

Explain the Frank Furcal Perforation a) Coronal perforation at the pulpal floor of multirooted tooth. b) Due to excessive deepening at the pulpal floor during access perfora

Explain the treatment of travelers diarrhea, Treatment of travelers'diarrhe...

Treatment of travelers'diarrhea  The most common cause of travelers' diarrhea, usually a self-limited illness lasting several days, is infection with noninvasive enterotoxigeni

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