notes of cell cycle
Answers
Answer:
The cell cycle involves many repetitions of cellular growth and reproduction. With few exceptions (for example, red blood cells), all the cells of living things undergo a cell cycle.
Explanation:
The cell cycle is generally divided into two phases: interphase and mitosis. During interphase, the cell spends most of its time performing the functions that make it unique. Mitosis is the phase of the cell cycle during which the cell divides into two daughter cells.
Interphase
The interphase stage of the cell cycle includes three distinctive parts: the G1 phase, the S phase, and the G2 phase. The G1 phase follows mitosis and is the period in which the cell is synthesizing its structural proteins and enzymes to perform its functions. For example, a pancreas cell in the G1 phase will produce and secrete insulin, a muscle cell will undergo the contractions that permit movement, and a salivary gland cell will secrete salivary enzymes to assist digestion. During the G1 phase, each chromosome consists of a single molecule of DNA and its associated histone protein. In normal human cells, there are 46 chromosomes per cell (except in sex cells with 23 chromosomes and red blood cells with no nucleus and, hence, no chromosomes).
During the S phase of the cell cycle, the DNA within the nucleus replicates. During this process, each chromosome is faithfully copied, so by the end of the S phase, two DNA molecules exist for each one formerly present in the G1 phase. Human cells contain 92 chromosomes per cell in the S phase.
In the G2 phase, the cell prepares for mitosis. Proteins organize themselves to form a series of fibers called the spindle, which is involved in chromosome movement during mitosis. The spindle is constructed from amino acids for each mitosis, and then taken apart at the conclusion of the process. Spindle fibers are composed of microtubules.
Answer:
the interphase stage of cell cycle includes three distinct parts .the G phase, the S phase, and the G²phase,.the G¹phase follows mitosis and is the period in which the cell synthesizing its structural proteins and enzymes to perform its functions .