Question

Read the given statements and select the correct option. Statement \(1:\) The cisternae in Golgi complex have cis face and trans face. Statement \(2:\) The cis face is also called forming face and trans face is also called maturing face. (a) Both statements 1 and 2 are correct and statement 2 is the correct explanation of statement 1 . (b) Both statements 1 and 2 are correct but statement 2 is not the correct explanation of statement 1 . (c) Statement 1 is correct and statement 2 is incorrect. (d) Both statements 1 and 2 are incorrect.

Short answer

(b) Both statements 1 and 2 are correct but statement 2 is not the correct explanation of statement 1.

Step-by-step solution

Understanding Golgi Complex

Review the structure of the Golgi complex which is an organelle found in most eukaryotic cells. It is composed of a series of flattened, stacked pouches called cisternae. The Golgi complex processes and bundles macromolecules like proteins and lipids as they are synthesized within the cell.

Identifying the Faces of Golgi Complex

Identify the two faces of the Golgi complex - the cis face and the trans face. The cis face is the side of the Golgi complex where substances enter, often from the endoplasmic reticulum. The trans face is the side where substances exit, going to various destinations within or outside of the cell.

Analyzing the Terminology

Examine the terminology used for the cis and trans faces. The cis face, where substances are received into the Golgi complex, is also known as the forming face because it is involved in the formation of new vesicles. The trans face is known as the maturing face because it is where the vesicles modify and finalize their contents before being sent off.

Evaluating the Statements

Evaluate the given statements based on the information from previous steps. Statement 1 correctly describes the presence of cis and trans faces in the Golgi complex. Statement 2 correctly defines the cis and trans faces as forming and maturing faces, respectively.

Selecting the Correct Option

Determine the relationship between the two statements. While both statements are correct in their description of the Golgi complex and its faces, statement 2 does not provide a direct explanation of statement 1; it only provides additional information about the terminology. Therefore, the correct option is that both statements are correct, but statement 2 is not the correct explanation of statement 1.

Key concepts

cis and trans faces of Golgi complex

The Golgi complex is an essential cellular organelle that functions as a molecular processing and distribution center. Understanding its structure is critical, particularly the roles of its distinct regions known as the cis and trans faces. Imagine the Golgi complex as a bustling post office where packages (biomolecules) are received, sorted, and dispatched.

The cis face, often referred to as the 'forming face', is where the sorting process begins. It's the entry-facing side of the Golgi complex, located near the endoplasmic reticulum (ER) from which it receives newly synthesized proteins and lipids. These molecules arrive in transport vesicles that fuse with the Golgi membranes at the cis face.

In contrast, the trans face, also called the 'maturing face', is akin to the dispatch area of the post office. It is on the opposite side of the Golgi complex and is where fully processed and packaged molecules are tagged for delivery to their specific destinations, such as the cell surface or other organelles. The molecular 'packages' leave the Golgi in vesicles that bud off from the trans face. These two distinct faces facilitate a directional flow of macromolecules through the Golgi apparatus, ensuring efficient post-translational modification and sorting.

Golgi cisternae

The structural and functional units of the Golgi complex are known as Golgi cisternae, which are a series of flattened, stack-like membranes. These cisternae are not static; they dynamically mature and progress from the cis to the trans face, carrying and modifying their molecular cargo as they move.

This maturation is crucial for the proper processing of macromolecules. Each cisterna within the stack is specialized, with different sets of enzymes that catalyze specific modifications to proteins and lipids, such as glycosylation and phosphorylation. The modifications that occur within the Golgi cisternae are highly ordered, and each cisterna has a unique chemical environment that tailors these processes.

Gradual Transformation

As cargo progresses through the cisternae, it undergoes a step-wise refinement that is akin to an assembly line process. The sequential modifications ensure that by the time the cargo reaches the trans face, it has been properly processed and is ready for export. The organization of Golgi cisternae is therefore not only important for biochemical modifications but also for the sorting and targeting of macromolecules to their correct destinations in or out of the cell.

macromolecule processing in cells

The processing of macromolecules within cells is a complex and essential activity, ensuring that proteins, lipids, and carbohydrates are correctly modified and directed towards their functional locales. The Golgi complex is particularly central in these endeavors, showcasing an impressive capability in both the chemical alteration and sorting of these large biological molecules.

Proteins and lipids synthesized in the endoplasmic reticulum are first transferred to the cis face of the Golgi complex. Upon entry, they embark on a journey through the cisternae, facing a series of modifications that may include the addition of sugar groups (glycosylation), the alteration of fatty acid chains, or the addition of other functional groups essential for their activity.

Quality Control and Addressing

After the macromolecules have been processed, they conclude their transit at the trans face of the Golgi. It is here that the final quality control checks occur; the molecules are properly 'addressed' with molecular tags that dictate whether they will be secreted from the cell, integrated into the cell membrane, or routed to other specific locations within the cell. This intricate process relies not only on the structural framework of the Golgi but also on the cellular signaling mechanisms that guide these macromolecules to their final destination, illustrating the cell's remarkable proficiency in managing its internal logistics.