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

What is elongation cycle , At the starting of the first round of elon...

At the starting of the first round of elongation, the initiation codon (AUG) is positioned in the P site with fMet-tRNAfMet bound to it by codon-anticodon base pairing.  In The nex

Define kingdom monera and protista?, Q. Which are the beings that constitut...

Q. Which are the beings that constitute the kingdom Monera? The kingdom Monera is the kingdom of the prokaryotes, archaebacteria and composed of bacteria. Q. Which are the

Preventive steps for global warming, Preventive steps for global warming : ...

Preventive steps for global warming :  Growing trees in vacant places. Growing social forests and protect them. Promoting abundant growth of phytoplankton plant species in marine

How old is the universe, How old is the universe? From the analysis of ...

How old is the universe? From the analysis of data collected by the Hubble telescope the age of the universe is estimated to be about 12 billion years.

Determine health hazards associated with high altitude, Determine Health Ha...

Determine Health Hazards Associated with High Altitude? Abrupt exposure to altitudes greater than 10,000 ft (3050 in) elevation is frequently associated with symptoins of altit

Avian (fowl cholera), Avian (fowl cholera) Fowl cholera is a contagious...

Avian (fowl cholera) Fowl cholera is a contagious septicaemic disease of almost all classes of fowl. The causal agent is Pasteurella multocida.Serotypes A:1 and A:3 are usually

Elephentiasis, Elephentiasis It is a disease seen all over the world...

Elephentiasis It is a disease seen all over the world. The adult worm lives in the lymph glands and the lymph vessels of man. As the number of worms increases, they bl

Occurrence of earthquake, Among the different natural hazards, earthquakes ...

Among the different natural hazards, earthquakes happen to be the most feared and dangerous because of their sudden impact and the devastation they cause in a matter of few seconds

Nutrition and health, Nutrition and Health The effects of the socio-ec...

Nutrition and Health The effects of the socio-economic and environmental factors in which one is constrained to live will manifest in terms of the nutritional and health statu

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