<h2 class="section-header"><strong class="title">Nucleus</strong></h2>
<p class="para">The nucleus is the largest organelle in the cell and contains all the cell's genetic information in the from of DNA. The presence of a nucleus is the primary factor that distinguishes <a data-lesson="characteristics-of-eukaryotes" data-subject="biology" data-tutorial="protists" href="https://app.ulearngo.com/biology/protists/characteristics-of-eukaryotes">eukaryotes</a> from prokaryotes. The structure of the nucleus is described below:</p>
<h3 class="para"><strong>Nuclear envelope</strong> </h3>
<p class="para">Two lipid membranes that are studded with special proteins that separates the nucleus and its contents from the cytoplasm.</p>
<h3 class="para">Nuclear pores</h3>
<p class="para">Tiny holes called nuclear pores are found in the nuclear envelope and help to regulate the exchange of materials (such as RNA and proteins) between the nucleus and the cytoplasm.</p>
<h3 class="para">Chromatin</h3>
<p class="para">Thin long strands of DNA and protein.</p>
<h3 class="para">Nucleolus</h3>
<p class="para">The nucleolus makes RNA another type of nucleic acid.</p>
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<h3 class="note-header"><span class="cnx_label">Fact:</span></h3>
<p class="para">During cell division, DNA contracts and folds to form distinct structures called chromosomes. The <a data-lesson="chromosomes" data-subject="biology" data-tutorial="cell-biology" href="https://app.ulearngo.com/biology/cell-biology/chromosomes">chromosomes</a> are formed at the start of cell division.</p>
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<h3 class="note-header"><span class="cnx_label">Fact:</span></h3>
<p class="para">The genetic material of eukaryotic organisms is separated from the <a data-lesson="cytoplasm" data-subject="biology" data-tutorial="introducing-the-cell" href="https://app.ulearngo.com/biology/introducing-the-cell/cytoplasm">cytoplasm</a> by a membrane whereas the genetic material of <a data-lesson="summarizing-prokaryotic-cell-division" data-subject="biology" data-tutorial="cell-reproduction" href="https://app.ulearngo.com/biology/cell-reproduction/summarizing-prokaryotic-cell-division">prokaryotic</a> organisms (like bacteria) is in direct contact with the cytoplasm.</p>
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<td><b class="emphasis">Schematic Diagram</b></td>
<td><b class="emphasis">Micrograph</b></td>
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<td>
<div class="figure"><a href="https://data.ulearngo.com/assets/8dae308f-5e65-47ba-8d07-d8956e467d63"><img alt="nucleus-schematic-diagram" class="size-full wp-image-100145 alignnone" height="218" src="https://data.ulearngo.com/assets/8dae308f-5e65-47ba-8d07-d8956e467d63" width="443"/></a></div>
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<div class="figure"><a href="https://data.ulearngo.com/assets/f30868ac-9111-4d0c-a0a1-3ffc9341de43"><img alt="nucleus-micrograph" class="size-full wp-image-100146 alignnone" height="243" src="https://data.ulearngo.com/assets/f30868ac-9111-4d0c-a0a1-3ffc9341de43" width="244"/></a></div>
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<h3 class="note-header"><span class="cnx_label">Fact:</span></h3>
<p class="para">Mitochondria also contain DNA, called mitochondrial DNA, (mtDNA) but it makes up just a small percentage of the cell's overall DNA content. All mitochondrial DNA in humans is derived from the mother's side.</p>
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<h3 class="para">Functions of the Nucleus</h3>
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<li class="item">The main function of the cell nucleus is to control <a href="https://app.ulearngo.com/tutorials/introducing-genetics/gene-expression-2">gene expression</a> and facilitate the replication of DNA during the <a data-lesson="cell-cycle" data-subject="biology" data-tutorial="cell-biology" href="https://app.ulearngo.com/biology/cell-biology/cell-cycle">cell cycle</a> (which you will learn about in the next chapter).</li>
<li class="item">The nucleus controls the <i class="emphasis">metabolic</i> functions of the cell by producing mRNA which encodes for <a data-lesson="enzymes-2" data-subject="biology" data-tutorial="biology-foundations" href="https://app.ulearngo.com/biology/biology-foundations/enzymes-2">enzymes</a> e.g. insulin.</li>
<li class="item">The nucleus controls the <i class="emphasis">structure</i> of the cell by transcribing DNA which encodes for structural proteins such as <a data-lesson="regulatory-proteins" data-subject="biology" data-tutorial="musculoskeletal-system" href="https://app.ulearngo.com/biology/musculoskeletal-system/regulatory-proteins">actin</a> and keratin.</li>
<li class="item">The nucleus is the site of ribosomal RNA (rRNA) synthesis, which is important for the construction of ribosomes. Ribosomes are the site of protein translation (synthesis of proteins from amino acids).</li>
<li class="item">Characteristics are transmitted from parent to <a data-lesson="reproduction-methods" data-subject="biology" data-tutorial="reproductive-system" href="https://app.ulearngo.com/biology/reproductive-system/reproduction-methods">offspring</a> through genetic material contained in the nucleus.</li>
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Nucleus

Biology studies life and living organisms. Biology can be divided into different sections that cover the morphology, physiology, anatomy, behavior, and so on of living organisms.

Biology

Discover the fascinating world of cells and explore topics such as microscopy, cell theory, membrane models, transport processes, organelles, and the cell cycle.


Nucleus

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