Tag: mitosis

The eukaryotic cell cycle follows a specific sequence: G1 phase, followed by the S phase (DNA synthesis), then the G2 phase, and finally the M phase (mitosis), which concludes with cytokinesis.

The cell cycle includes a series of events, that take place  in a cell which leads to the duplication of DNA and division of cells to form two daughter cells. This takes place in three different  periods and can be referred to as Interphase , Mitotic phase(M) and cytokinesis. While during the interphase or the initial phase, the cells grow in size and is ready for division, during the mitosis, the DNA starts duplicating, the nuclear membrane dissolves and the cells starts its division process to give rise to  two distinct daughter cells. Cytokinesis is the stage during which the two daughter cells are formed and separated.
So, the correct answer is option D.

In a typical 18-hour mitotic cell cycle, the interphase phases (G1, S, G2) and M phase take up proportional durations, with G1 being the longest, followed by S, G2, and M being the shortest. The ratio corresponding to 9, 5, 3, 1 hours correctly totals 18 hours.

One cell cycle of yeast is almost 90 minutes and a human cell takes almost 24 hours to divide by mitosis therefore by calculations it seems that a yeast can perform mitosis almost 16 times in the time of 1 division of a human cell.

The cell cycle was discovered and demonstrated by Alma Howard and Stephen R. Pelc in 1953 using root meristem cells of Vicia faba and radioactive thymidine labeling.

At the start, the culture of E. coli has cell population of 1.5 X 10$^6$ cells/ml. After first generation, it will be doubled, that is 3 X 10$^6$ cells/ml. After second generation, it will be 6 X 10$^6$ cells/ml. After third generation, it will be 12 X 10$^6$ cells/ ml. It is given that for a cell population to increase from 1. 5 X 10$^6$ cells/ml to 12 X 10$^6$ cells/ml, it takes 36 minutes. It means, for 3 generation, it takes 36 minutes. So, its generation time is 36/3 = 12.

Through phosphorylation, Cdks signal the cell that it is ready to pass into the next stage of the cell cycle. As their name suggests, Cyclin-Dependent ProteinKinases are dependent on cyclins, another class of regulatory proteins. Cyclins bind to Cdks, activating the Cdks to phosphorylate other molecules.

So, the correct option is ‘binding to cyclin, plus, phosphorylation by Cdk activating protein kinases’.

The death of cells which occurs as a normal and controlled part of an organism's growth or development is called apoptosis. In this endoplasmic reticulum, lysosome, mitochondria, Golgi complex are involved.

So, the correct option is ‘ER, lysosome, mitochondria’. 

The cell progresses through defined phases of the cell cycle during its division.

Interphase is the longest part of the cell cycle, occupying approximately 90 to 95 percent of the total time in most actively dividing cells.