Flashcards for:
Lecture on the Cell Cycle

Advanced topics include aging and telomere shortening, additional checkpoints like the G2/M checkpoint and metaphase checkpoint, and understanding regulatory mechanisms to control cell cycle errors.

A cell is classified by having a cell membrane (phospholipid bilayer), nucleus (houses genetic material, chromatin), and cytoplasm.

During telophase, chromosomes decondense, the nuclear envelope re-forms, and cytokinesis completes the division by forming a cleavage furrow to separate the cytoplasm into two cells.

During the G2 phase, the cell grows by increasing its cytoplasm and cellular components to ensure it is large enough to divide.

The phases of mitosis are Prophase (chromatin condenses, nuclear envelope dissolves), Metaphase (chromosomes align at the metaphase plate), Anaphase (sister chromatids separate), and Telophase (chromosomes decondense, nuclear envelope re-forms, cytokinesis completes).

The G1/S checkpoint ensures a cell's readiness for DNA replication during the cell cycle.

During prophase, chromatin condenses into chromosomes, the nuclear envelope dissolves, and centrioles appear to organize microtubules.

Checkpoints are crucial in ensuring smooth transitions between phases, preventing errors, and maintaining genomic integrity through processes like DNA repair.

During the G1 phase, the cell increases the number of organelles, synthesizes proteins and enzymes for DNA replication, and repairs thymine dimers in DNA.

The primary goal of the cell cycle is to duplicate DNA and replicate new double-stranded DNA, ultimately turning one cell into two.

The S phase is where DNA replication occurs, involving the formation of a replication bubble and operating under the semi-conservative model with DNA polymerases ensuring high fidelity.

The G0 phase is a quiescent phase where cells exit the cell cycle and temporarily or permanently stop dividing, often entering a resting state.

Labile cells proliferate constantly (e.g., skin epithelium), stable cells replicate only with strong stimulus (e.g., liver hepatocytes), and permanent cells do not replicate again (e.g., neurons).

During anaphase, motor proteins like dynein and kinesin facilitate the movement of chromatids to opposite poles, aiding in the separation process.

The metaphase plate is significant because it is where chromosomes align, allowing microtubules to properly attach to chromatids via the kinetochore to ensure proper separation.