<h2>Endoplasmic Reticulum</h2>
<p class="para">The endoplasmic reticulum (ER) is an organelle found in eukaryotic cells only. The ER has a double membrane consisting of a network of hollow tubes, flattened sheets, and round sacs. These flattened, hollow folds and sacs are called cisternae. The ER is located in 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> and is connected to the nuclear envelope. There are two types of endoplasmic reticulum: smooth and rough ER.</p>
<h3 class="para">Smooth ER</h3>
<p class="para">Does not have any ribosomes attached. It is involved in the synthesis of lipids, including oils, phospholipids and steroids. It is also responsible for <a data-lesson="metabolism" data-subject="biology" data-tutorial="protists" href="https://app.ulearngo.com/biology/protists/metabolism">metabolism</a> of carbohydrates, regulation of calcium <a data-lesson="basic-principles-of-gas-exchange" data-subject="biology" data-tutorial="respiratory-system" href="https://app.ulearngo.com/biology/respiratory-system/basic-principles-of-gas-exchange">concentration</a> and detoxification of drugs.</p>
<h3 class="para">Rough ER</h3>
<p class="para">Is covered with ribosomes giving the endoplasmic reticulum its rough appearance. It is responsible for <a data-lesson="tertiary-and-quaternary-protein-structures" data-subject="biology" data-tutorial="biological-macromolecules" href="https://app.ulearngo.com/biology/biological-macromolecules/tertiary-and-quaternary-protein-structures">protein</a> synthesis and plays a role in membrane production. The folds present in the membrane increase the surface area allowing more ribosomes to be present on the ER, thereby allowing greater protein production.</p>
<table>
<tbody>
<tr>
<td><b class="emphasis">Schematic Diagram</b></td>
<td><b class="emphasis">Micrograph</b></td>
</tr>
<tr>
<td colspan="2">Smooth endoplasmic reticulum</td>
</tr>
<tr>
<td><a href="https://data.ulearngo.com/assets/00dcd474-f38c-4049-ae00-95c94e8bb1c2"><img alt="Smooth endoplasmic reticulum" class="size-full wp-image-100154 alignnone" height="92" src="https://data.ulearngo.com/assets/00dcd474-f38c-4049-ae00-95c94e8bb1c2" width="458"/></a></td>
<td><a href="https://data.ulearngo.com/assets/579585d0-ebd1-4928-8bed-cbf60dd0ae1a"><img alt="Smooth endoplasmic reticulum micrograph" class="size-full wp-image-100155 alignnone" height="229" src="https://data.ulearngo.com/assets/579585d0-ebd1-4928-8bed-cbf60dd0ae1a" width="229"/></a></td>
</tr>
<tr>
<td colspan="2">Rough endoplasmic reticulum</td>
</tr>
<tr>
<td><a href="https://data.ulearngo.com/assets/47d0f719-b0cd-490a-b0fa-029bcde6111c"><img alt="Rough endoplasmic reticulum" class="size-full wp-image-100156 alignnone" height="120" src="https://data.ulearngo.com/assets/47d0f719-b0cd-490a-b0fa-029bcde6111c" width="420"/></a></td>
<td><a href="https://data.ulearngo.com/assets/06b5d25e-5882-4de8-9339-de5dc952f541"><img alt="Rough endoplasmic reticulum micrograph" class="size-full wp-image-100157 alignnone" height="229" src="https://data.ulearngo.com/assets/06b5d25e-5882-4de8-9339-de5dc952f541" width="229"/></a></td>
</tr>
</tbody>
</table>
<h2 class="section-header"><strong class="title">Ribosomes</strong></h2>
<p class="para">Ribosomes are composed of <a href="https://app.ulearngo.com/tutorials/introducing-genetics/rna">RNA</a> and protein. They occur in the cytoplasm and are the sites where protein synthesis occurs. Ribosomes may occur singly in the cytoplasm or in groups or may be attached to the endoplasmic reticulum thus forming the rough endoplasmic reticulum. Ribosomes are important for protein production. Together with a structure known as messenger RNA (a type of nucleic acid) ribosomes form a structure known as a polyribosome which is important in protein synthesis.</p>
<table>
<tbody>
<tr>
<td><b class="emphasis">Diagram</b>: Free Ribosome</td>
<td><b class="emphasis">Diagram</b>: Polyribosome</td>
</tr>
<tr>
<td><a href="https://data.ulearngo.com/assets/fd7d6e71-892a-4b6c-851f-641465706358"><img alt="free-ribosome" class="size-full wp-image-100158 alignnone" height="98" src="https://data.ulearngo.com/assets/fd7d6e71-892a-4b6c-851f-641465706358" width="367"/></a></td>
<td><a href="https://data.ulearngo.com/assets/2a2c8851-a4bf-466d-8900-0ca38c660a63"><img alt="polyribosome" class="size-full wp-image-100160 alignnone" height="100" src="https://data.ulearngo.com/assets/2a2c8851-a4bf-466d-8900-0ca38c660a63" width="367"/></a></td>
</tr>
</tbody>
</table>

ad260561-7f24-4cf8-a3f2-b129f5e47c91

Endoplasmic Reticulum and Ribosomes

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.


Endoplasmic Reticulum and Ribosomes

Track Your Learning Progress