Exceptions to the cell theory, Biology

Exceptions to the Cell Theory

Viruses, however, are not the only exception to the Cell Theory as formulated earlier. This has led scientists to take a much broader view of the problem. some organisms like a bacterium, blue-green alga, mycoplasma, amoeba, Chlamydomonas and Mucor are composed basically of a single cell.-In such cases we face another problem. You have so far learnt that the cell is the basic structural unit of an organism, something like bricks in a building.

But in the examples cited above just a single cell constitutes the whole animal, which amazingly performs all the body functions like respiration, digestion, excretion, etc. The problem is further complicated by the occurrence of many multinucleate protozoans, multinucleate animal tissues etc.For example a species of amoeba, Chaos as well as also many other protists like the ciliate Opalina have many nuclei in their body. The common. pond plant Nitella has giant cells with many nuclei in the cytoplasm. There are also tissues and cells in our body which have many nuclei.

Such cells are called syncytial. For example, the striated muscle fibres of our body are syncytial in nature. The problems listed above arose due to the fact that Cell Theory was proposed on the basis of observations on multicellular organism. This created a wrong notion that single celled organisms were totally comparable to a cell of multicellular organisms. It is however, now established beyond any doubt that as it stands today, the present unified Cell Theory given below, is universally applicable with equal force from bacteria to protozoa to humans except for viruses.

Posted Date: 1/12/2013 2:58:29 AM | Location : United States







Related Discussions:- Exceptions to the cell theory, Assignment Help, Ask Question on Exceptions to the cell theory, Get Answer, Expert's Help, Exceptions to the cell theory Discussions

Write discussion on Exceptions to the cell theory
Your posts are moderated
Related Questions
Q. Explain about Dietary Management? Treatment for gout often include a diet of lower purine intake. Indeed, about one third of the body's uric acid can be attributed to diet.

Functions of cerebrum The forebrain is otherwise called as ‘cerebrum'. It is highest centre for controlling several functions in the body, The most interesting aspect

What is Polymerase Chain Reactionin genetics? A great advance in sequencing and cloning DNA is the polymerase chain reaction, devised by the American biochemist Kary Mullis in

Q. What is an example of positive feedback of the homeostatic regulation? In positive feedback the effect caused by an action stimulates the action even more. This is a rarer m

Surgical Considerations in anterior mandibular region During the harvesting of a monocortical symphyseal block of bone from the mandibular symphysis region (autogenous block bo

To verify the effect of intra-specific competition on the growth of saplings of Eucalyptus dives, an experiment was designed in which two sets of pots were used. In the first set o

What are the typical vegetation and the typical fauna of the tropical forests? In the vegetation of the tropical forests broadleaf evergreen trees predominate. On the top of th

M protein of rheumatogenic GAS has distinct structural characteristics that are akin to human heart tissue, particularly sarcolemmal membrane proteins and cardiac myosin. The major

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

Q. Fats requirements for ulcerative colitis? Usual foods, which contain fats (invisible or inherent fat), are permitted but not fried foods, as they are not easily digested due