7 Cell Cycle, Mitosis, Meiosis, and Chromosome Biology – Vocabulary Flashcards

Vocabulary flashcards covering key terms related to the cell cycle, mitosis, meiosis, chromosome structure, karyotypes, ploidy, and cancer biology.

Interphase

The cell cycle stage in which the cell grows, replicates DNA, and prepares for division; comprises G1, S, and G2.

G1 phase

Growth and preparation for DNA replication; cell increases in size and synthesizes new organelles.

S phase

DNA replication occurs, producing sister chromatids for each chromosome.

G2 phase

Final preparation for mitosis; checks that DNA has been replicated correctly and is undamaged.

M phase

Mitotic phase; includes mitosis (nuclear division) and cytokinesis (cytoplasmic division).

Mitosis

Nuclear division that distributes a complete set of chromosomes into two daughter nuclei, producing two genetically identical cells.

Cytokinesis

Division of the cytoplasm, yielding two distinct daughter cells; in animals, via a cleavage furrow; in plants, via a cell plate.

Cleavage furrow

Contractile actin ring pinches the plasma membrane to split an animal cell during cytokinesis.

Cell plate

Vegetative vesicles coalesce at the center of a plant cell to form a cell wall between daughter nuclei.

Mitotic spindle

Microtubule-based apparatus that separates chromosomes during mitosis.

Centrosome

Main microtubule-organizing center of a cell; often contains a pair of centrioles in animals.

Kinetochore

Protein structure at the centromere where spindle microtubules attach to chromosomes.

Centromere

Constricted region of a chromosome where sister chromatids are held together and where kinetochores form.

Sister chromatids

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

Chromosome

Condensed DNA-protein complex visible during mitosis; comprises two sister chromatids held together at the centromere.

DNA double helix

Two anti-parallel DNA strands wound around each other forming the molecule of DNA.

Nucleosome

DNA wrapped around a histone octamer, the basic unit of chromatin.

Chromatin

DNA-protein complex; condenses to form chromosomes during cell division.

Condensin

Protein complex that helps compress and condense chromosomes during mitosis.

Cohesin

Protein complex that holds sister chromatids together until anaphase.

Prophase

Chromosomes condense and become visible; the mitotic spindle forms; the nuclear envelope begins to break down.

Prometaphase

Nuclear envelope breaks down; kinetochores attach to spindle microtubules; chromosomes move toward the metaphase plate.

Metaphase

Chromosomes align along the metaphase plate; kinetochores attached to opposite poles ensure equal division.

Anaphase

Sister chromatids separate and are pulled toward opposite poles; the cell elongates as microtubules lengthen.

Telophase

Chromosomes arrive at poles, de-condense, and the nuclear envelope re-forms around each set.

G1 checkpoint

Assesses cell size, energy reserves, and DNA integrity; if conditions are unfavorable, the cell may enter G0.

G2 checkpoint

Verifies DNA replication is complete and undamaged before mitosis begins.

M checkpoint (spindle checkpoint)

Ensures each sister chromatid is properly attached to the spindle before anaphase starts.

Cyclins

Proteins whose levels fluctuate with the cell cycle and activate Cdks to drive progression.

Cyclin-dependent kinases (Cdks)

Kinases that, when bound to cyclins, phosphorylate target proteins to push the cell cycle forward.

Proto-oncogenes

Normal genes that promote cell cycle progression; may become oncogenes when mutated.

Oncogenes

Mutated genes that drive uncontrolled cell growth and division.

Tumor suppressors

Genes that restrain the cell cycle and promote DNA repair or apoptosis when needed.

p53

Tumor suppressor and “guardian of the genome” that detects DNA damage and can halt the cell cycle or trigger apoptosis.

p21

CDK inhibitor induced by p53; helps enforce cell-cycle arrest.

Rb (retinoblastoma protein)

Tumor suppressor that binds E2F to prevent S-phase entry until phosphorylated.

E2F

Transcription factor that activates genes required for S-phase entry.

DNA double helix (redundant)

Two complementary strands of DNA wound into a double helix.

Sister chromatids (redundant)

Identical copies of a duplicated chromosome held together at the centromere.

Haploid

A cell with one complete set of chromosomes (n); typical of gametes.

Diploid

A cell with two complete sets of chromosomes (2n); typical of somatic cells.

Gamete

A haploid reproductive cell (sperm or egg) that fuses during fertilization.

Meiosis

Type of cell division that reduces chromosome number by half to form haploid gametes; two rounds (Meiosis I and II).

Meiosis I

Reductional division; homologous chromosomes pair (synapsis) and separate, producing two haploid cells.

Meiosis II

Equational division; sister chromatids separate, resulting in four haploid cells.

Synapsis

Pairing of homologous chromosomes during prophase I of meiosis.

Tetrad

paired homologous chromosomes (each with two sister chromatids) formed during prophase I.

Crossing over

Exchange of genetic material between non-sister chromatids of homologous chromosomes, creating variation.

Chiasmata

Points where crossing over occurs between chromatids.

Synaptonemal complex

Protein lattice that holds homologous chromosomes together during prophase I.

Independent assortment

Random orientation of homologous chromosome pairs at metaphase I, generating genetic diversity.

Random fertilization

Unpredictable fusion of a random sperm with a random egg, increasing genetic variation.

Karyotype

Organized visual profile of an organism's chromosomes, used to study number, size, and structure.

Ploidy

Number of chromosome sets in a cell (n, 2n, 3n, etc.).

Metacentric

Chromosome with the centromere near the middle; arms are roughly equal in length.

Submetacentric

Centromere off-center, producing unequal chromosome arms.

Acrocentric

Centromere near one end, resulting in a very small p arm.

Telocentric

Centromere at the very end of the chromosome; effectively no p arm.

p arm

Short arm of a chromosome.

q arm

Long arm of a chromosome.

Spore

A haploid reproductive cell in plants, fungi, and some bacteria that can give rise to a new organism.

Gametophyte

Haploid multicellular stage in plants that produces gametes.

HPV E6 protein

Viral protein that binds and inactivates p53, undermining checkpoint control.

Guardian of the genome

Nickname for p53 due to its crucial role in maintaining genomic integrity.

Sperm and egg

Male and female gametes, respectively; combine during fertilization to form a diploid zygote.

Golgi vesicles

Vesicles derived from the Golgi apparatus that contribute to forming the plant cell plate during cytokinesis.