Cell Transport — Role of Golgi Apparatus & ER

How Are Things Transported Around the Cell?

The cell uses two important organelles to move things around and out of the cell. They are the Golgi apparatus and the endoplasmic reticulum.

(Video) Endoplasmic Reticulum

by learnbiologically

This video explains what the endoplasmic reticulum is, where it is, and what it does.

Transporting Things Within and Out of the Cell

Rough ER and Smooth ER

The rough and the smooth endoplasmic reticulum work together to make protein products for use both inside the cell and outside the cell.

The rough ER is the source of protein synthesis because it has ribosomes embedded in its surface. After proteins are made in the rough ER, they are sent to the smooth ER. Here, they are packed into vesicles and sent to the Golgi apparatus for further modification.

The smooth ER creates a vesicle of phospholipids and places receptors on the phospholipid membrane so that the Golgi apparatus can recognize the proteins. The endoplasmic reticulum places an address tag called a signal sequence on the packaged proteins.

Protein Synthesis in the Rough ER

Proteins are created on the inside of the rough ER, in the lumen. The lumen is the space inside of the endoplasmic reticulum, separated from the cytosol. Once the protein is completed inside the lumen, it's important that the protein folds correctly so it functions properly. The unique environment in the rough ER makes this possible. In the rough ER, proteins can also be tagged with special molecules which tell the cell to send the protein to different locations either inside or outside the cell.

Smooth ER: It Does Lots of Jobs

The smooth ER lacks ribosomes and therefore lacks the ability to produce proteins. However, the smooth ER has several other crucial functions. Among these functions are lipid and steroid production. Another key function of the smooth ER is detoxification. If anything toxic enters the cell, it's the smooth ER's job to neutralize the substance so it doesn't harm the cell. One more function of the smooth ER is that it is the location of calcium storage within the cell.

What Does The Golgi Apparatus Do?

The Golgi apparatus is an organelle that packages and transports proteins and lipids received from the endoplasmic reticulum. This organelle is often called the post office of the cell because it determines the final destination of products. It works by placing the received proteins and lipids into a vesicle and tagging them to help the cell determine where to send them. They can be kept within the cell for use or sent out of the cell via exocytosis.

How Do the Golgi Apparatus and Endoplasmic Reticulum Help With Cell Transport?

Rough ER vs. Smooth ER

The smooth and rough endoplasmic reticulum (ER) assist with the creation and transport of many substances. They are both membrane-bound organelles present within a cell.

Rough Endoplasmic Reticulum

The rough endoplasmic reticulum (RER) is similar to the smooth ER, but it is studded with ribosomes. The embedded ribosomes make proteins that are moved around by transport vesicles.

Vesicles form when the edges of the rough ER are pinched off with shipping materials inside. This is known as active transport. This organelle works with the Golgi apparatus to transport the newly made proteins to wherever they are needed.

Smooth Endoplasmic Reticulum

The smooth endoplasmic reticulum (SER) assembles the lipid parts of the cell membrane and helps with the detoxification of drugs. It also assists in the transport of macromolecules.

It's called smooth because it's literally smooth: this part of the ER does not contain any ribosomes. It is a complex network of flattened tubes.

Cellular Post Offices

The Golgi apparatus (also called the Golgi complex or Golgi body) is known as the post office of the cell. It is found close to the nucleus of the cell.

The Golgi apparatus sorts, packages, and modifies a variety of materials made in the RER. The packaged materials can be "shipped" both into and out of the cell. These materials range from lipids to proteins, many of which were made inside the cell. Similar to the RER, the Golgi apparatus pinches off its outer edges to form transport vesicles for shipping.

$$\color{#8925AE}{\text{Vocabulary Review:}}$$

$\color{#8925AE}{\text{Golgi Apparatus}}$ : Stores, sorts, and modifies proteins and lipids. Post office of the cell

$\color{#8925AE}{\text{Ribosome}}$ : Creates polypeptide chains and proteins. Factory of the cell

$\color{#8925AE}{\text{Smooth Endoplasmic Reticulum}}$ : The SER makes lipids for the cellular membrane

$\color{#8925AE}{\text{Rough Endoplasmic Reticulum}}$ : The RER assembles proteins and transports them into and out of the cell

$\color{#8925AE}{\text{Vacuole}}$ : Organelle that contains water and nutrients. Refrigerator of the cell

(Video) Protein Trafficking

by ndsuvirtualcell

Proteins are sorted and labeled by the Golgi apparatus. Check out this animated video by NDSU to see how this ever-changing organelle functions.