Cell Cycle and Cancer Biology

These flashcards cover key vocabulary and concepts related to the cell cycle, cancer biology, and the underlying mechanisms that regulate cellular behavior.

Cell Cycle

The complete series of phases that a eukaryotic cell goes through, from its formation to its division into two daughter cells. It primarily consists of Interphase (G1, S, G2) and the Mitotic (M) phase.

Interphase

The stage of the cell cycle where a cell spends most of its time growing and performing its normal functions, while also preparing for cell division. It includes the G1, S, and G2 phases.

G1 Phase

The first gap phase of Interphase, where a newly formed cell grows in size, synthesizes proteins and organelles, and carries out its normal metabolic functions. The cell also checks for DNA damage and favorable conditions for division.

S Phase

The synthesis phase of Interphase, during which the cell replicates its entire DNA content. This results in each chromosome consisting of two identical sister chromatids, joined at the centromere.

G2 Phase

The second gap phase of Interphase, where the cell continues to grow, synthesizes proteins necessary for mitosis, and prepares for cell division. A crucial checkpoint ensures DNA replication is complete and any damage is repaired before entering mitosis.

Mitosis

The process of nuclear division in eukaryotic cells that produces two genetically identical diploid daughter nuclei. It is followed by cytokinesis, leading to the formation of two separate cells.

Prophase

The first phase of mitosis where replicated chromosomes condense and become visible. The nuclear envelope begins to break down, and the mitotic spindle (composed of microtubules) starts to form from the centrosomes.

Metaphase

The second phase of mitosis characterized by the alignment of condensed chromosomes along the metaphase plate (the equatorial plane) of the cell. Spindle microtubules from opposite poles attach to the kinetochores of each sister chromatid.

Anaphase

The third phase of mitosis where sister chromatids separate from each other, pulled by the shortening spindle microtubules towards opposite poles of the cell. Each separated chromatid is now considered an individual chromosome.

Telophase

The final phase of mitosis where the separated chromosomes arrive at opposite poles and begin to decondense. New nuclear envelopes form around each set of chromosomes, and the nucleoli reappear. The mitotic spindle disassembles.

Cytokinesis

The process of cytoplasmic division that usually follows nuclear division (mitosis or meiosis). It results in the physical separation of the parent cell into two distinct daughter cells, each with its own nucleus and cytoplasm.

G0 Phase

A quiescent or resting phase outside the active cell cycle, where cells are not actively preparing to divide. Cells in G0 still perform their specialized functions, and some may re-enter the cell cycle under specific conditions (e.g., liver cells).

Apoptosis

Programmed cell death, an orderly and genetically regulated process where cells undergo a series of biochemical events leading to their systematic dismantling and removal without causing inflammation. It is crucial for development and tissue homeostasis.

Oncogene

A mutated gene that promotes uncontrolled cell growth and division, thus contributing to the development of cancer. Oncogenes often arise from proto-oncogenes that normally regulate the cell cycle.

Proto-oncogene

A normal gene that, when mutated or overexpressed, can become an oncogene. Proto-oncogenes typically encode proteins that stimulate cell growth, division, and differentiation.

BRCA Mutations

Inherited mutations in the BRCA1 or BRCA2 genes, which are tumor suppressor genes involved in DNA repair. These mutations significantly increase a person's risk of developing certain cancers, particularly breast and ovarian cancer.

Tumor

An abnormal mass of tissue resulting from uncontrolled cell proliferation and impaired apoptosis. Tumors can be either benign (non-cancerous) or malignant (cancerous).

Benign Tumor

A non-cancerous tumor that typically grows slowly, remains localized to its original site, and does not invade surrounding tissues or metastasize. Benign tumors are generally not life-threatening unless they grow large enough to compress vital organs.

Malignant Tumor

A cancerous tumor characterized by uncontrolled cell growth, invasion of surrounding tissues, and the potential to spread to distant parts of the body (metastasis). Malignant tumors are often life-threatening and require treatment.

Checkpoints

Critical regulatory points within the cell cycle that ensure cells progress through the phases in an orderly and accurate manner. They monitor conditions like DNA integrity, cell size, and chromosome attachment to the spindle, arresting the cycle if problems are detected.

Chemotherapy

A type of cancer treatment that uses powerful drugs to kill or slow the growth of rapidly dividing cancer cells throughout the body. However, it can also affect healthy rapidly dividing cells, leading to side effects.

Radiation Therapy

A cancer treatment that uses high-energy radiation (such as X-rays, gamma rays, or protons) to damage the DNA of cancer cells, thereby killing them or inhibiting their growth and division. It is often directed at specific tumors.

Histone Proteins

A group of basic proteins found in eukaryotic cell nuclei that package and organize DNA into structural units called nucleosomes. Histone modifications play a crucial role in regulating gene expression by affecting chromatin structure.

Eukaryotes

Organisms whose cells contain a distinct nucleus enclosed within a nuclear membrane, as well as other membrane-bound organelles (like mitochondria, endoplasmic reticulum, and Golgi apparatus). Their genetic material is organized into chromosomes.

Epigenetics

The study of heritable changes in gene expression that occur without altering the underlying DNA sequence. These changes include DNA methylation and histone modifications, which can influence how genes are turned on or off.

Tumor Suppressor Gene

A gene that normally regulates cell growth, prevents uncontrolled cell division, repairs DNA damage, or induces apoptosis when necessary. Mutations in tumor suppressor genes can lead to uncontrolled cell proliferation and cancer development (e.g., p53, Rb).

Metastasis

The process by which cancer cells detach from a primary tumor, invade surrounding tissues, enter the bloodstream or lymphatic system, and travel to distant parts of the body to form secondary tumors (metastases).

Meiosis

A specialized type of cell division that occurs in sexually reproducing organisms, resulting in four genetically distinct haploid daughter cells (gametes) from a single diploid parent cell. It involves two rounds of division (Meiosis I and Meiosis II) and is essential for genetic diversity.