Biology Unit: Cell Cycle, Mitosis, Differentiation, and Cancer

Vocabulary flashcards covering the eukaryotic cell cycle, the stages of mitosis and cytokinesis, cellular differentiation, and cell cycle checkpoints related to cancer.

Mitosis

The division of the nucleus that results in 2 identical daughter cells with the same number of chromosomes, serving as a form of asexual reproduction following interphase.

Centromere

The central region connecting sister chromatids by which chromosomes are counted; humans have $46$ chromosomes per cell.

Centrosomes

Organelles that produce spindle fibers and migrate to opposite poles of the cell during prophase.

Prophase

The first phase of mitosis in which chromosomes condense from long stringy DNA, the nucleus disappears, centrosomes move to opposite poles, and spindle fibers form.

Metaphase

The shortest phase of mitosis where chromosomes line up at the middle of the cell (metaphase plate) and spindle fibers connect to the centromere of each pair of sister chromatids.

Anaphase

The phase of mitosis in which sister chromatids are separated by spindle fibers and move toward opposite ends (poles) of the cell.

Telophase

The phase of mitosis where chromosomes decondense back into long stringy form, a nucleus reforms around each set of chromosomes to create 2 nuclei, spindle fibers dissolve, and cytokinesis begins.

Cytokinesis

The division of the cytoplasm into two separate cells following mitosis.

Cleavage furrow

A groove formed in animal cells by a contractile ring that pinches the cell membrane inward to divide the cell into two equal cells.

Cell plate

A structure formed by Golgi vesicles between the two nuclei in dividing plant cells that gradually develops into a separate membrane and cell wall.

Cell Cycle

The repeated pattern of growth and division occurring in eukaryotic cells that consists of two main phases: Interphase and M phase.

Interphase

The period where a cell spends the majority of the cell cycle growing and preparing for division, ending with 2 full sets of DNA and sufficient size to divide.

$G_1$ Phase

The gap 1 phase of interphase during which the cell grows and synthesizes proteins.

$S$ Phase

The synthesis phase of interphase where chromosomes replicate to form identical DNA.

$G_2$ Phase

The gap 2 phase of interphase where cells continue to grow and produce the proteins necessary for cell division.

$G_0$ Phase

A resting state where a cell is not going through the division cycle but continues to perform its normal job.

Cell Differentiation

The irreversible process through which a cell becomes specialized in structure and function by activating specific parts of its DNA.

Stem Cell

An undifferentiated or unspecialized cell that contains identical DNA to all other body cells and retains the potential to differentiate into specialized cell types.

Embryonic Stem Cell

The least specialized type of cell that possesses the full potential to develop into any specialized cell type.

C. elegans

An adult microscopic worm containing exactly $959$ cells, serving as an ideal model for studying cellular differentiation due to its small cell count.

Checkpoints

Critical control points regulated by proteins where stop and go signals regulate the cell cycle, requiring the cell to meet all conditions before dividing.

$G_1$ Checkpoint

A cell cycle control point between the $G_1$ and $S$ phases that inspects cell size, nutrient availability, and DNA damage.

$G_2$ Checkpoint

A cell cycle control point between the $G_2$ phase and mitosis that checks cell size and confirms proper DNA replication.

Spindle Checkpoint

An M checkpoint occurring at the end of metaphase before anaphase that verifies spindle fiber attachment to all chromosomes so each new cell receives one sister chromatid.

Apoptosis

Controlled cell death that occurs when a cell fails to meet checkpoint requirements and cannot repair itself.

Cancer

A condition of uncontrolled cell division that arises when mutated cells bypass cell cycle checkpoints and ignore normal regulatory signals.

Benign tumor

A non-harmful, abnormal mass of cells that remains at its original site and does not interfere with organ function.

Malignant tumor

A harmful mass of cancer cells that impairs and prevents normal organ function.

Metastatic cancer

Cancer cells that detach from the original tumor, travel through the bloodstream to other areas of the body, and spread the disease.