+
Endoplasmic Reticulum

Endoplasmic Reticulum

Description:

This lesson will describe the structure and function of a cell's endoplasmic reticulum.

(more)
See More
Try a College Course Free

Sophia’s self-paced online courses are a great way to save time and money as you earn credits eligible for transfer to over 2,000 colleges and universities.*

Begin Free Trial
No credit card required

25 Sophia partners guarantee credit transfer.

221 Institutions have accepted or given pre-approval for credit transfer.

* The American Council on Education's College Credit Recommendation Service (ACE Credit®) has evaluated and recommended college credit for 20 of Sophia’s online courses. More than 2,000 colleges and universities consider ACE CREDIT recommendations in determining the applicability to their course and degree programs.

Tutorial

What's Covered

Welcome to today’s lesson on endoplasmic reticulum. In this lesson today you are going to learn about the endoplasmic reticulum. Specifically, you will look at:

  1. Endoplasmic Reticulum Overview
  2. Endoplasmic Reticulum’s Role
  3. Endoplasmic Reticulum Parts

1. Endoplasmic Reticulum Overview

So the endoplasmic reticulum is an organelle that is found in eukaryotic cells.

Term to Know

Endoplasmic Reticulum

A cell organelle that assembles and packages proteins and lipids

If you remember from previous lessons, eukaryotic cells are cells that have a nucleus.

Example Our cells, for example, are eukaryotic cells, so an endoplasmic reticulum is an organelle that would be found in our cells.

Hint

If you were to think of the cell as a factory and think of the organelles as different parts of the factory, the endoplasmic reticulum would be like a packager perhaps. So it's like a highway where materials are moving through this endoplasmic reticulum and getting ready to get packaged and sent off to other parts of the cells.

The endoplasmic reticulum also works closely with another organelle called the Golgi body or the Golgi apparatus. They help to prep materials and get them packaged to be sent out to different parts of the cell.


2. Endoplasmic Reticulum’s Role

So the endoplasmic reticulum's role is to synthesize and package proteins and lipids in the cell. There are two parts of the endoplasmic reticulum: the smooth and the rough endoplasmic reticulum.

Hint

You'll often see endoplasmic reticulum abbreviated as ER. So when you see ER just know that we're talking about the endoplasmic reticulum.

The endoplasmic reticulum is part of the endomembrane system, a system that makes lipids, modifies proteins, and helps to package those molecules that will be sent out to different parts of the cell wherever they're needed. The endomembrane system includes the endoplasmic reticulum and the Golgi apparatus.

Term to Know

Endomembrane System

A system of cellular structures including the endoplasmic reticulum, nuclear envelope, golgi body, and vesicles that is used to synthesize and package proteins and lipids


3. Endoplasmic Reticulum Parts

As you learn about the function of the endoplasmic reticulum, please refer to the image below.

The endoplasmic reticulum starts at the nuclear envelope; the blue part of the drawing is the nucleus. Surrounding the nucleus we have the nuclear envelope, that's where the endoplasmic reticulum begins.

1. Rough ER

The rough endoplasmic reticulum is attached to the nuclear envelope; the part in yellow is the rough ER. The reason that you call it rough ER is because it has ribosomes attached to it.

Terms to Know

Ribosomes

A cell organelle responsible for synthesizing proteins

Rough Endoplasmic Reticulum

A part of the endoplasmic reticulum with proteins embedded in it - mainly responsible for assembling and packaging proteins

So the little dots all over the place are ribosomes. What happens in this part of the endoplasmic reticulum are that newly formed polypeptide chains will enter this part of the endoplasmic reticulum, and then side chains will be added onto them to help complete that protein.

The function of ribosomes is to build proteins, and proteins that are built by ribosomes can have many different roles. They can act enzymes, they can take place in the production of hormones and regulate hormones, or they can regulate different cell functions. In the image above the ribosomes are on the rough ER, but ribosomes can also be found floating around in the cytoplasm. They don't always have to be attached to the endoplasmic reticulum. Finally, ribosomes are made up of two subunits and the parts of those ribosomes are made in the nucleus.

2. Smooth ER

The pink part of the drawing above is the smooth endoplasmic reticulum.

Term to Know

Smooth Endoplasmic Reticulum

A part of the endoplasmic reticulum responsible for mostly packaging lipids

So the smooth ER is called the smooth ER because it does not have any ribosomes attached to it.

Hint

The names of the different parts of the ER are fairly easy to remember: rough and smooth, depending on if they have ribosomes attached or not.

The smooth endoplasmic reticulum's job is to assemble lipids. So lipids or fats are assembled in the smooth endoplasmic reticulum.


Summary

This lesson has been an overview of the endoplasmic reticulum; specifically you learned about the role of the endoplasmic reticulum and the major parts of the endoplasmic reticulum.

Keep up the learning and have a great day!

Source: THIS WORK IS ADAPTED FROM SOPHIA AUTHOR AMANDA SODERLIND

TERMS TO KNOW
  • Endomembrane System

    A system of cellular structures including the endoplasmic reticulum, nuclear envelope, golgi body, and vesicles that is used to synthesize and package proteins and lipids

  • Smooth Endoplasmic Reticulum

    A part of the endoplasmic reticulum responsible for mostly packaging lipids

  • Rough Endoplasmic Reticulum

    A part of the endoplasmic reticulum with proteins embedded in it - mainly responsible for assembling and packaging proteins

  • Ribosomes

    A cell organelle responsible for synthesizing proteins

  • Endoplasmic Reticulum

    A cell organelle that assembles and packages proteins and lipids