Question

Which organelles are most active during cell division? a. ribosomes b. endoplasmic reticulum c. Golgi apparatus d. centrioles e. cilia

Short answer

d. centrioles

Step-by-step solution

- Understanding Cell Division

During cell division, the cell undergoes several processes to ensure that the genetic material is accurately divided between the daughter cells. It is crucial to identify the organelles involved in these processes.

- Identify Functions of Given Organelles

Analyze each organelle to understand their respective roles: a) Ribosomes are involved in protein synthesis. b) The Endoplasmic Reticulum (ER) is responsible for protein and lipid synthesis. c) The Golgi Apparatus modifies, sorts, and packages proteins and lipids. d) Centrioles play a key role in the formation of the spindle fibers that separate chromosomes during cell division. e) Cilia are involved in movement and are not typically associated with cell division.

- Determine the Most Active Organelle

Based on the functions of the organelles, centrioles are directly involved in cell division. They play a crucial role in the formation of the spindle apparatus which is essential for chromosome separation during mitosis and meiosis.

- Conclude

As the centrioles are directly responsible for a critical part of cell division, they are the most active organelles during this process.

Key concepts

Centrioles and Their Role in Cell Division

Centrioles are small, cylindrical organelles found in animal cells. They are particularly crucial during cell division, specifically in the processes of mitosis and meiosis. Here, centrioles help in forming spindle fibers, which are essential for separating chromosomes into the two daughter cells.
Centrioles are made up of microtubules arranged in a specific pattern. These structures come in pairs and are positioned perpendicular to each other.

• During the initial phase of cell division (prophase), centrioles move to opposite poles of the cell.
• As they migrate, they assist in organizing the spindle apparatus.

This organization is vital for chromosome alignment and separation, ensuring genetic material is evenly distributed.

The Stages and Importance of Mitosis

Mitosis is a process where a single cell divides to produce two identical daughter cells. This is crucial for growth, development, and tissue repair. Mitosis consists of several stages, each with specific events that ensure proper division.
During prophase, chromatin condenses into visible chromosomes, and the nuclear envelope breaks down.
Metaphase follows, where chromosomes align at the cell’s equatorial plate, or metaphase plate. Next is anaphase, during which spindle fibers pull the sister chromatids apart to opposite poles of the cell.

Lastly, during telophase, the nuclear envelope re-forms around the separated chromatids, now individual chromosomes, in each pole.

• Mitosis ensures that each daughter cell receives an identical set of chromosomes.
• Proper spindle fiber formation and attachment to chromosomes are critical here.

This means centrioles and spindle fibers play indispensable roles in maintaining genetic consistency from one cell generation to the next.

Spindle Fibers: The Key Players in Chromosome Movement

Spindle fibers are microtubule structures that play an essential role during cell division. They are responsible for moving chromosomes during mitosis.
Spindle fibers form from the centrosomes (which include centrioles) at the cell’s poles during prophase. These fibers then extend towards the chromosomes.

• In metaphase, spindle fibers attach to chromosomes at the centromere through protein complexes called kinetochores.
• During anaphase, these fibers shorten, pulling the sister chromatids apart to opposite sides of the cell.

Without spindle fibers, chromosomes could not be separated accurately, leading to potential genetic disorders. The precise operation and formation of spindle fibers are thus critical for healthy cell division and the maintenance of proper chromosomal number in daughter cells.