Test: Cellular Division - MCAT MCQ

Separase is an enzyme that cleaves the cohesin protein complex, allowing the sister chromatids to separate and move to opposite poles of the cell during anaphase of mitosis. This process ensures the accurate distribution of genetic material to the daughter cells.

p53 is a tumor suppressor protein that plays a critical role in monitoring DNA integrity. When DNA damage is detected, p53 can initiate apoptosis, a programmed cell death, to prevent the proliferation of cells with damaged DNA, reducing the risk of mutations and cancer development.

Mitosis is a single division process that results in the formation of two genetically identical daughter cells. On the other hand, meiosis involves two rounds of cell division (meiosis I and meiosis II), resulting in the formation of four genetically unique haploid daughter cells.

Independent assortment occurs during meiosis I when homologous chromosomes pair up and align randomly at the metaphase plate. This random alignment results in different combinations of maternal and paternal chromosomes in the daughter cells, contributing to genetic diversity.

DNA replication occurs during the S (synthesis) phase of the cell cycle. In this phase, the DNA is duplicated, resulting in the formation of two identical copies of each chromosome, called sister chromatids.

The APC/C is a protein complex that plays a crucial role in regulating the cell cycle. It targets specific proteins, including securin and cyclin B, for degradation. By degrading securin, APC/C allows separase to cleave cohesin and separate sister chromatids during anaphase.

The G0 phase is a non-dividing state that some cells enter instead of proceeding through the cell cycle. Cells in G0 phase are in a resting state, carrying out their specialized functions without actively dividing. This phase is common in cells like neurons and muscle cells that have exited the cell cycle permanently.

Histones are proteins that play a crucial role in organizing and compacting DNA into a condensed form. During mitosis and meiosis, histones help in the coiling and condensation of chromosomes, allowing for their proper segregation and movement during cell division.

Telomerase is an enzyme that is responsible for the maintenance and replication of telomeres, which are specialized structures at the ends of chromosomes. Telomerase helps prevent the shortening of telomeres during DNA replication and ensures chromosome stability. Dysfunctional telomerase activity can lead to cellular senescence or genetic instability.

The spindle checkpoint is a control mechanism that ensures the accurate alignment of chromosomes at the metaphase plate before allowing the cell to progress into anaphase. It monitors the attachment of chromosomes to the spindle fibers and prevents the separation of sister chromatids until all chromosomes are correctly positioned and attached to the spindle apparatus.