The Cell Cycle, Mitosis, and Meiosis - Vocabulary

Vocabulary flashcards covering key terms and definitions from the cell cycle, mitosis, meiosis, gametogenesis, chromosome structure, and related disorders.

Interphase

Cell growth phase where cellular contents are duplicated and DNA is replicated; includes G1, S, and G2; longest phase.

G1 (Gap 1)

First gap phase; cell grows, organelles double, and cell mass increases; duration varies by cell type.

G0

Resting or permanent withdrawal from the cell cycle for some cells.

S phase (Synthesis)

DNA replication occurs; each chromosome is duplicated to form sister chromatids.

G2 (Gap 2)

Second gap phase; prepares for mitosis, checks DNA integrity, and produces proteins needed for mitosis.

Mitosis

Nuclear division producing two identical nuclei; PMAT stages occur in somatic (diploid) cells.

Prophase

Chromosomes condense; spindle apparatus forms; centrosomes move; nuclear envelope breaks down; nucleolus disappears.

Metaphase

Chromosomes align at the metaphase plate; kinetochores attach chromosomes to spindle fibers.

Anaphase

Sister chromatids separate and migrate to opposite poles; centromeres split.

Telophase

Chromosomes arrive at poles, decondense; nuclear envelope reforms; nucleolus reappears; spindle breaks down.

Cytokinesis

Division of the cytoplasm to produce two separate daughter cells; follows mitosis.

Cleavage furrow

Indentation that forms during cytokinesis in animal cells, driven by a contractile actin-myosin ring.

Contractile ring

Actin-myosin filament ring that constricts the cell membrane to split the cell during cytokinesis.

Nucleolus

Nuclear region where rRNA is synthesized; disappears during prophase.

Nuclear envelope

Membrane around the nucleus; breaks down in prophase, reforms in telophase.

Kinetochore

Protein structure at the centromere that attaches chromosomes to spindle microtubules.

Centromere

Region of a chromosome where sister chromatids are held together; attachment site for kinetochores.

Chromatid

One of two identical copies of a duplicated chromosome; together they form sister chromatids.

Sister chromatids

Two identical copies of a duplicated chromosome held at the centromere.

Chromosome

DNA-protein structure; condensed form of genetic material; consists of two sister chromatids after replication.

Tubulin

Protein that polymerizes to form microtubules of the spindle.

Microtubule

Cylindrical protein filament forming the spindle apparatus that separates chromosomes.

Spindle apparatus

Network of microtubules and other proteins that segregates chromosomes during mitosis.

Metaphase plate

Imaginary plane where chromosomes align during metaphase.

Meiosis

A special cell division producing haploid gametes through two successive divisions, reducing chromosome number by half.

Meiosis I

Reduction division; homologous chromosomes separate, producing two haploid cells with duplicated chromosomes.

Meiosis II

Equational division; sister chromatids separate, producing four haploid gametes.

Prophase I

Meiosis I stage where chromosomes condense, homologous chromosomes pair (synapsis), and crossing over occurs.

Leptotene

Early Prophase I stage; chromosomes condense and become visible.

Zygotene

Prophase I stage where homologous chromosomes pair (synapsis) to form bivalents.

Pachytene

Prophase I stage where crossing over occurs between non-sister chromatids; synaptonemal complex forms.

Diplotene

Prophase I stage where homologs begin to separate but remain connected at chiasmata.

Diakinesis

Final Prophase I stage; chromosomes fully condensed, nuclear envelope breaks down, spindle forms.

Synapsis

Pairing of homologous chromosomes during Prophase I.

Synaptonemal complex

Protein structure that holds homologous chromosomes together during synapsis.

Tetrad

Structure formed by paired homologous chromosomes (two homologs each with two sister chromatids).

Crossing over

Exchange of genetic material between non-sister chromatids during Prophase I, creating recombinant chromosomes.

Chiasmata

Points where crossing over has occurred between homologous chromosomes.

Independent assortment

Random orientation of homologous chromosome pairs during Metaphase I, increasing genetic variation.

Metaphase I

Homologous chromosome pairs (tetrads) align at the metaphase plate; homologs attach to spindle fibers.

Anaphase I

Homologous chromosomes separate to opposite poles; centromeres do not split; cells become haploid.

Telophase I

Spindle breaks down; chromosomes may de-condense; cytoplasm divides; two haploid daughter cells form.

Meiosis II

Second meiotic division; similar to mitosis; sister chromatids separate to yield four haploid gametes.

Gametogenesis

Process of forming mature gametes (sperm or eggs) from germ cells.

Spermatogenesis

Meiosis and differentiation producing sperm; occurs in testes; regulated by hormones; continuous after puberty.

Oogenesis

Meiosis and differentiation producing eggs; occurs in ovaries; yields a mature ovum with polar bodies.

Spermatogonia

Male germline stem cells that divide to maintain the population of spermatogonia.

Sertoli cells

Nurse/support cells in the testes that nourish developing sperm cells.

Leydig cells

Testicular cells that produce testosterone.

Epididymis

Duct where sperm mature and are stored after leaving the testes.

Diploid (2n)

Cell containing two complete sets of chromosomes.

Haploid (n)

Cell containing a single set of chromosomes.

Down syndrome (Trisomy 21)

A genetic disorder caused by an extra copy of chromosome 21.

Turner syndrome (XO)

Monosomy X in females; short stature and infertility.

Klinefelter syndrome (XXY)

Males with an extra X chromosome; underdeveloped secondary sexual characteristics.

Polar bodies

Small haploid cells produced during oogenesis; typically degenerate.

Oogonia

Diploid germ cells that divide to form primary oocytes in females.

Primary oocyte

Diploid cell that undergoes meiosis to form eggs; arrested in various stages before fertilization.

Secondary oocyte

Oocyte after meiosis I; arrested at metaphase II until fertilization.

Spermatozoon

Male gamete; mature sperm cell.

Spermatids

Male germ cells that differentiate into mature sperm during spermatogenesis.

Ovum

Mature egg cell; female gamete.

Karyokinesis

Nuclear division that partitions the genetic material into daughter nuclei.

PMAT

Acronym for Prophase, Metaphase, Anaphase, Telophase—the stages of mitosis.