Correct option is B
Explanation-
The cell cycle is the ordered series of events that a cell goes through to grow and divide, consisting of:
1. G1 phase – cell grows
2. S phase – DNA synthesis/replication
3. G2 phase – preparation for mitosis
4. M phase (mitosis) – cell divides
To study cell cycle progression, scientists observe how cells move through these phases — this requires tools that track DNA synthesis, division, and timing.
Option A - Artificial thymidine analog BrdU
BrdU = Bromodeoxyuridine, a synthetic analog of thymidine.
During S-phase, when DNA is being replicated, cells incorporate BrdU instead of thymidine into DNA. After BrdU is added to cell culture, cells are fixed and stained with anti-BrdU antibodies. The amount of BrdU in a cell tells if the cell was in S-phase. BrdU directly marks DNA synthesis, making it very useful for tracking S-phase entry and cell cycle progression.
Correct and standard tool.
Option B - Kinase inhibitor, LY294002
A PI3K inhibitor (phosphoinositide 3-kinase inhibitor). PI3K is involved in cell survival, metabolism, and growth signaling pathways. LY294002 blocks PI3K signaling → affects pathways like AKT/mTOR, which regulate cell survival, proliferation, and sometimes cell cycle entry. But it does not allow direct visualization or tracking of cell cycle progression. It may indirectly affect cell cycle by stopping cells from entering cycle, but it doesn’t help in measuring or visualizing specific cell cycle phases. No direct info about which phase cells are in. So not typically used to study cell cycle progression.
Option C - Flow Cytometry Analysis
A technique that measures properties of individual cells in a mixed population. Cells are stained with a DNA-binding dye (e.g., propidium iodide).
The amount of DNA content is measured:
1. G1 phase → 2n DNA
2. S phase → between 2n and 4n
3. G2/M phase → 4n DNA
Widely used and highly reliable method for cell cycle analysis.
Option D - Live Cell Imaging
Using fluorescent reporters or markers to image living cells in real time.
Example - The FUCCI system: uses fluorescence proteins to mark G1 (red), S (green), etc. We can watch a single cell as it moves from G1 → S → G2 → M.
Provides real-time, dynamic understanding of how cells move through the cycle.
The correct answer is option B - Kinase inhibitor, LY294002
It is not typically used to study cell cycle progression because it affects signaling pathways indirectly, not the cycle itself.
