Here's why:
* Centrioles are essential for cell division. They form the poles of the mitotic spindle, which guides the separation of chromosomes.
* G1 phase is the "growth phase" where the cell increases in size and produces new organelles and proteins. This includes duplicating centrioles in preparation for mitosis.
Other cellular components made in G1:
* Ribosomes: Essential for protein synthesis, they are continually produced throughout the cell cycle, including G1.
* Mitochondria: These organelles are responsible for energy production and also replicate independently during G1.
* Other proteins and enzymes: Many proteins and enzymes necessary for cell function are synthesized throughout the cell cycle, including G1.
Important Note: While the centrioles are the most significant structure made specifically during G1, other cellular components are also being produced and modified during this phase.
