Regulating the Cell Cycle

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Growth Factor Noun

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[grohth fak-ter]

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Growth Factor

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An external regulatory protein that stimulates the growth and division of cells, important for development and wound healing.

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Example: Growth factors are external signals that tell normal cells when to divide, while their absence stops division, thus regulating the cell cycle.

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Cyclin Noun

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[sai-klin]

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Cyclin

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A family of proteins that regulate the timing of the cell cycle in eukaryotic cells by rising and falling in concentration.

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Example: This graph shows that the concentration of different cyclins (proteins) increases and decreases at specific times to control the cell's progression through its cycle phases.

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Apoptosis Noun

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[ap-uhp-toh-sis]

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Apoptosis

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A process of programmed cell death, involving a series of controlled steps that lead to a cell's self-destruction.

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Example: This diagram shows the steps of apoptosis, or programmed cell death, where a normal cell shrinks, breaks apart, and is cleaned up by another cell.

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Cancer Noun

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[kan-ser]

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Cancer

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A disorder where body cells lose the ability to control growth, resulting in uncontrolled cell division and tumor formation.

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Example: A normal cell undergoes genetic changes, turning it into a cancer cell which then divides uncontrollably, forming a mass of malignant cells.

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Tumor Noun

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[too-mer]

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Tumor

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A mass of abnormal cells formed by uncontrolled cell growth, which can be either benign or malignant in nature.

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Example: This image shows a tumor, which is a mass of abnormal cells that form when the cell cycle is no longer regulated, causing uncontrolled cell division.

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Regulatory Proteins Noun

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[reg-yuh-luh-tor-ee proh-teenz]

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Regulatory Proteins

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A group of proteins, both internal and external to the cell, that control the progression of the cell cycle.

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Example: A signal molecule binds to a regulatory protein, changing its shape. This change activates the protein, allowing it to attach to DNA and control a cell's activity.

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Benign Tumor Noun

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[bih-nahyn too-mer]

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Benign Tumor

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A noncancerous mass of cells that does not spread to surrounding healthy tissue or other parts of the body.

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Example: This diagram shows a benign tumor, a contained mass of cells (fat tissues) enclosed in a fibrous capsule, which keeps it from spreading.

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Malignant Tumor Noun

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[muh-lig-nuhnt too-mer]

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Malignant Tumor

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A cancerous tumor that invades and destroys surrounding healthy tissue and can spread to other parts of the body.

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Example: This diagram shows a malignant tumor as a cluster of abnormal cells, with some breaking away to invade other areas, illustrating how cancer spreads.

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Metastasis Noun

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[muh-tas-tuh-sis]

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Metastasis

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The process by which cancer cells spread from their original site to other parts of the body, forming secondary tumors.

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Example: Cancer cells from a primary tumor (e.g., in the lung) break away and travel to another part of the body, forming a new metastatic tumor (e.g., in the brain).

Front

p53 Gene Noun

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[pee-fif-tee-three jeen]

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p53 Gene

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A gene that codes for a protein that acts as a checkpoint, halting the cell cycle until chromosomes are properly replicated.

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Example: This diagram shows how the p53 protein, when activated, can influence other genes to help control or stop the cell cycle from proceeding.