The Cell Cycle and Mitosis

Vocabulary flashcards covering key terms and concepts from the lecture on the cell cycle, mitosis sub-phases, and experimental methods used to measure cell cycle dynamics.

Cell Cycle

The ordered sequence of events in a cell’s life, consisting of interphase (G1, S, G2) and M phase (mitosis + cytokinesis).

Interphase

Portion of the cell cycle outside M phase, comprising G1, S, and G2 phases where the cell grows, duplicates DNA, and prepares for mitosis.

G1 Phase

Interphase sub-phase where the cell grows, synthesizes proteins, and decides whether to divide.

S Phase

Interphase sub-phase in which DNA replication occurs, producing two sister chromatids for each chromosome.

G2 Phase

Interphase sub-phase following DNA replication; cell continues to grow and prepares mitotic machinery.

M Phase

Mitotic phase of the cell cycle, including mitosis (nuclear division) and cytokinesis (cytoplasmic division).

Mitosis

Division of the nucleus into two genetically identical daughter nuclei; sub-phases are prophase, metaphase, anaphase, telophase.

Prophase

First mitotic stage where chromatin condenses, sister chromatids become visible, nucleolus disappears, nuclear envelope fragments, and spindle begins forming.

Metaphase

Mitotic stage where chromosomes align on the equatorial plane and spindle fibers attach from poles to kinetochores.

Anaphase

Mitotic stage where sister chromatids separate at the centromere and are pulled toward opposite spindle poles.

Telophase

Mitotic stage where spindle disassembles, chromosomes decondense back to chromatin, and nuclear envelopes & nucleoli re-form.

Cytokinesis

Physical separation of cytoplasm that produces two independent daughter cells; involves a contractile ring forming a cleavage furrow.

Chromatin

DNA-protein complex that condenses into visible chromosomes during mitosis.

Sister Chromatids

Identical copies of a replicated chromosome held together by a centromere until anaphase.

Centromere

Region where sister chromatids are joined and the kinetochore assembles, crucial for chromosome segregation.

Mitotic Spindle

Bipolar array of microtubules that orchestrates chromosome movement during mitosis.

Kinetochore

Protein structure on the centromere where spindle microtubules attach.

Equatorial Plane (Metaphase Plate)

Imaginary plane midway between spindle poles where chromosomes align during metaphase.

Microtubule Antagonist (Colcemid)

Drug that prevents spindle fiber assembly, arresting cells in metaphase and allowing visualization of chromosomes.

Bromodeoxyuridine (BrdU)

Artificial thymidine analog incorporated into DNA during S phase; detected with anti-BrdU antibody to identify cells in DNA synthesis.

3H Thymidine

Radioactive thymidine used to measure DNA synthesis kinetics by assessing incorporation into replicating DNA.

Hydroxyurea

Inhibitor of deoxyribonucleotide synthesis that stalls cells in S phase; useful for synchronizing cell cycles.

Asynchronous Cell Population

Cell culture in which individual cells are in different phases of the cell cycle.

Contractile Ring

Actin-myosin structure that constricts the plasma membrane to form the cleavage furrow during cytokinesis.

Cell Cycle Length Determination

Calculated by measuring the fraction of cells in a given phase (e.g., mitosis or S phase) and multiplying by total cycle time.