Nucleus, Biology

Assignment Help:

Nucleus -

  • Largest component of the cell.
  • Nucleus is double membrane bound dense protoplasmic body that controls cellular metabolism, enclose all the genetic information, and is able to transmit the same to the next generation.
  • Leeuwenheek first seen nucleus in fish R.B.C.
  • Robert Brown coined the name nucleus. Robert Brown observed nucleus in pollen grain and stigma cells.
  • Boveri indicated significance of nucleus in heredity.
  • J. Hemmerling while working on unicellular alga Acetabularia proved that nucleus regulates the activity of cytoplasm and also heredity.
  • Except mature mammalian R.B.C. and Sieve cell of phloem every living cell has a nucleus.
  • Procaryotes have incipient nucleus devoid of nuclear membrane, nucleolus and histone. Such type of nucleus is called nucleoid.
  • Details of nuclear structure, come to be known only after its study under electron microscope.
  • Nucleus of undividing cell is called interphase nucleus.

NUMBER, SIZE, POSITION & SHAPE

  • Normally a cell has single nucleus, this condition is called Uninucleate / Mononucleate / Monokaryotic.
  • Sometimes a cell may have two nuclei called Binucleate / Dikaryotic cell e.g. Paramaecium caudatum has one macronucleus and one micronucleus, macronucleus controls metabolic activities and micronucleus controls genetic information. Paramaecium aurelia isTrinucleate with one macronucleus and two micronuclei.
  • Multinucleate condition found in striated muscle cells, latex vessels, Opalina, Ascaris, polycaryoctes of bone marrow, fungi (Rhizopus) and algae (Vaucheria), which are formed by free nuclear divisions.
  • Multinucleate condition in plants is called Coenocyte (coenocytic) whereas multinucleate condition in animals is called Syncytium.Multinucleate condition present in slime molds is called Plasmodium. Cell wall less fungi is called plasmodium. Coenocytic condition is formed by repeating karyokinesis and Syncytium condition is formed by fusion of cells.
  • Nucleus usually occupies 20% of cells mass. Its size depend upon ploidy, cell maturity and cell function.
  • Nucleus lies near the geometric centre of the cell, peripharal nucleus present in adipocytes & plant cells.
  • Nucleus is rounded in young plants and polygonal in animal cells, oval or elliptical in mature plant cells.

 

 


Related Discussions:- Nucleus

What are the applications of pcr, Polymerase chain reaction already has ext...

Polymerase chain reaction already has extremely widespread applications and new uses are being devised on a regular basis. Some and definitely not all of the applications are given

Floating stage - hydrarch, Floating Stage - Hydrarch The pond is now c...

Floating Stage - Hydrarch The pond is now colonised by plant species which are rooted in mud but their leaves reach water surface and float. These are species of Nelumbo, Nymp

Citric acid cycle, Citric Acid Cycle The citric acid cycle, also known ...

Citric Acid Cycle The citric acid cycle, also known as tricarboxylic acid (TCA) cycle, lies at the heart of aerobic metabolism. it is involved in the breakdown of all three maj

What is growth monitoring of an infant, What is Growth Monitoring? In t...

What is Growth Monitoring? In third world countries, about half the children are short and underweight for their age. Inadequate nutrient intake is the main reason. Inadequate

Deficiency diseases-downer cow syndrome, Downer cow syndrome This syndr...

Downer cow syndrome This syndrome is a common sequel to milk fever. The term is commonly applied to those hypocalcaemic cows that remain recumbent for several hours before bein

What is hmp pathway, What is HMP pathway? Give any two points of its signif...

What is HMP pathway? Give any two points of its significance The HMP  is an alternate oxidative pathway for the metabolism of glucose. The significance of the pathway  is that

What are the possible effects on the fetus, What are the possible effects o...

What are the possible effects on the fetus if, during pregnancy, the mother (a) smokes, (b) catches rubella?   a) Smoking during pregnancy can lead to an underwe

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

Compare and contrast the effect of a deletion, Compare and contrast the eff...

Compare and contrast the effect of a deletion in the operator of the lactose operon with one in the operator of the histidine operon.

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