Endoplasmic Reticulum Quiz

What is one of the key functions of the smooth endoplasmic reticulum?

The smooth endoplasmic reticulum plays a major role in the synthesis of protein substances.

What major substance does the smooth endoplasmic reticulum store and metabolize?

Smooth endoplasmic reticulum is involved in the __________ of toxic substances in the liver.

Match the following functions to the smooth endoplasmic reticulum:

What is the main function of rough endoplasmic reticulum?

Smooth endoplasmic reticulum has a bumpy appearance due to attached ribosomes.

What are the two types of endoplasmic reticulum?

The diameter of the lumen of endoplasmic reticulum is about _____ to _____ Å.

Match the following functions with their respective types of endoplasmic reticulum:

Which organelle is mainly responsible for modifying proteins synthesized in the rough endoplasmic reticulum?

Both types of endoplasmic reticulum are disconnected and operate independently.

What structure is formed when rough endoplasmic reticulum wraps around worn-out organelles?

Endoplasmic Reticulum Overview

Composed of interconnected tubular and microsomal vesicular structures.
Surrounded by a membrane made of proteins and bilayered lipids.
The lumen (endoplasmic matrix) diameter is approximately 400 to 700 Å.
Connects the nucleus to the cell membrane, establishing a communication pathway.

Types of Endoplasmic Reticulum

Divided into two main types: rough and smooth.
Both types are interconnected and can transform into one another based on cellular activity.

Rough Endoplasmic Reticulum (RER)

Characterized by a bumpy appearance due to attached ribosomes; also known as granule endoplasmic reticulum.
Structure is tubular or vesicular.
Main functions include:
- Protein Synthesis: Primarily synthesizes secreted proteins, such as insulin and antibodies. Ribosomes facilitate amino acid assembly into proteins, which are then glycosylated (carbohydrates added) to form glycoproteins.
- Transport: Vesicles containing proteins are transported to the Golgi apparatus for modification; some vesicles go to other organelles.
- Degradation: Involved in degrading worn-out organelles by wrapping around them to form autophagosomes, which are digested by lysosomal enzymes.

Smooth Endoplasmic Reticulum (SER)

Appears smooth and is also referred to as agranular reticulum; consists of interconnected tubules.
Functions include:
- Synthesis of Non-Protein Substances: Produces cholesterol, steroids, lipids, phospholipids, and lipoproteins, especially in cells responsible for lipid synthesis.
- Cellular Metabolism: Contains enzymes on its outer surface that perform various metabolic processes.
- Storage and Metabolism of Calcium: Major reservoir for calcium; releases calcium ions in skeletal muscles to trigger contractions.
- Catabolism and Detoxification: Engaged in the breakdown and detoxification of toxic substances, including drugs and carcinogens, particularly in liver cells.

Test your knowledge on the structure and function of the endoplasmic reticulum. This quiz covers its characteristics, including its limiting membrane and connection to the nucleus and cell membrane. Explore key concepts related to this important cellular organelle.