Cell Division – Vocabulary Flashcards

A comprehensive set of vocabulary flashcards covering essential terms and definitions on the cell cycle, mitosis, checkpoints, cytokinesis, and meiosis, suitable for exam review.

Cell Cycle

Ordered sequence of events in a cell’s life from formation to its own division.

Interphase

Phase of the cell cycle that includes G1, S, and G2; period of growth and DNA replication.

G1 Phase

First gap of interphase; cell grows, synthesizes lipids, carbohydrates, proteins, and new organelles.

S Phase

Synthesis phase of interphase; DNA replicates, forming identical sister chromatids, and histones are produced.

G2 Phase

Second gap of interphase; cell enlarges, duplicates centrosomes, forms microtubules, and prepares for mitosis.

Mitotic (M) Phase

Portion of the cell cycle including mitosis (nuclear division) and cytokinesis (cytoplasmic division).

G0 Phase

Non-dividing state that cells may enter from G1 when conditions are unfavorable or specialization occurs.

Mitosis

Division of a eukaryotic nucleus into two genetically identical nuclei; consists of prophase, metaphase, anaphase, telophase.

Cytokinesis

Division of the cytoplasm that produces two separate daughter cells, usually during telophase.

Karyokinesis

Another term for nuclear division, synonymous with mitosis.

Prophase

First stage of mitosis; chromatin condenses, spindle apparatus begins to form, nucleolus disappears.

Metaphase

Stage of mitosis where chromosomes align on the metaphase plate; spindle fibers attach to centromeres.

Anaphase

Stage of mitosis where centromeres split and sister chromatids move to opposite poles.

Telophase

Final stage of mitosis; chromosomes decondense, nuclear envelopes and nucleoli re-form, spindle disassembles.

Cleavage Furrow

Contractile ring-induced groove that pinches an animal cell during cytokinesis.

Cell Plate

Structure formed by Golgi-derived vesicles in plant cells that develops into a new cell wall during cytokinesis.

Centrosome

Microtubule-organizing center that duplicates during G2 and forms spindle poles.

Spindle Fibers

Microtubules that attach to chromosomes and orchestrate their movement during division.

Aster

Radial array of short microtubules extending from each centrosome.

Checkpoint

Control point where stop-and-go signals regulate the cell cycle (G1, G2, M).

G1 Checkpoint

Verifies adequate size, nutrients, and undamaged DNA before DNA synthesis.

G2 Checkpoint

Ensures DNA replication is complete and undamaged before mitosis.

M Checkpoint

Confirms all chromosomes are attached to spindle fibers before anaphase.

Cyclin

Protein whose fluctuating concentration activates Cdks to drive the cell cycle.

Cyclin-Dependent Kinase (Cdk)

Protein kinase activated by cyclin binding; phosphorylates targets to advance the cell cycle.

Cyclin-Cdk Complex

Active enzyme complex that provides the cell with a go-ahead signal at checkpoints.

Cancer

Disease resulting from loss of cell-cycle control causing uncontrolled cell division.

Benign Tumor

Localized mass of abnormal cells that does not invade surrounding tissue.

Malignant Tumor

Mass of abnormal cells that invades new tissues and impairs organ function; defines cancer.

Chromatin

DNA-protein complex that condenses into chromosomes during cell division.

Chromosome

Condensed threadlike structure of DNA and protein carrying genetic information.

Chromatid

One of two identical halves of a duplicated chromosome.

Sister Chromatids

Pair of identical chromatids joined at a centromere after DNA replication.

Homologous Chromosomes

Pair of chromosomes identical in size, gene loci, and centromere position, one from each parent.

Centromere

Constricted region linking sister chromatids; site of kinetochore formation.

Kinetochore

Protein complex at the centromere where spindle microtubules attach.

Meiosis

Two-successive nuclear divisions producing four genetically diverse haploid cells.

Meiosis I

Reductional division separating homologous chromosomes; includes Prophase I to Telophase I.

Meiosis II

Equational division separating sister chromatids; similar to mitosis.

Synapsis

Pairing of homologous chromosomes during Prophase I.

Bivalent

Paired homologous chromosomes undergoing synapsis; contains two chromosomes.

Tetrad

Synapsed homologous pair visible as four chromatids during Prophase I.

Chiasma

Visible crossover site where nonsister chromatids exchange DNA.

Crossing Over

Genetic exchange between nonsister chromatids during Prophase I, increasing variation.

Independent Assortment

Random orientation of homologous pairs at Metaphase I that generates genetic diversity.

Leptotene

First substage of Prophase I; chromosomes begin condensing into thin threads.

Zygotene

Second Prophase I substage; synapsis occurs and synaptonemal complex forms.

Pachytene

Third Prophase I substage; crossing over takes place as synapsis completes.

Diplotene

Fourth Prophase I substage; synaptonemal complex disassembles, homologues start separating, chiasmata visible.

Diakinesis

Final Prophase I substage; chromosomes fully condensed, chiasmata terminalize, nuclear envelope breaks down.

Metaphase I

Stage where homologous pairs align at the metaphase plate, attached to spindle fibers from opposite poles.

Anaphase I

Homologous chromosomes (not sister chromatids) separate and move to opposite poles.

Telophase I

Chromosomes reach poles, nuclei may reform; each nucleus now haploid.

Prophase II

Chromatin condenses in each haploid cell; new spindle forms, nuclear envelope dissolves.

Metaphase II

Chromosomes align singly on metaphase plate; no chiasmata present.

Anaphase II

Centromeres split and sister chromatids migrate to opposite poles.

Telophase II

Chromosomes decondense, nuclei reform, cytokinesis yields four distinct haploid cells.

Asexual Reproduction

Production of offspring from one parent via mitosis, producing genetically identical clones.

Somatic Cell

Non-reproductive body cell that undergoes mitosis.

Germ Cell

Reproductive cell that undergoes meiosis to form gametes.

Genetic Variation

Differences in DNA sequences among individuals, enhanced by crossing over and independent assortment.

Spore

Haploid cell produced by meiosis in plants; can develop into a gametophyte.

Gamete

Haploid reproductive cell (sperm or ovum) formed by meiosis in animals.