Cell Division & Chromosome Mechanics

Interphase

Phase where the cell grows, replicates DNA, and prepares for division.

Prophase

Chromosomes condense, spindle forms, nuclear envelope breaks down.

Metaphase

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

Anaphase

Sister chromatids separate and move to opposite poles.

Telophase

Nuclear envelopes reform; chromosomes decondense.

Cytokinesis

Division of cytoplasm, forming two daughter cells.

Mitosis

Nuclear division producing two genetically identical diploid cells.

Meiosis

Division producing four genetically diverse haploid gametes.

Chromosome

Condensed form of DNA; consists of two sister chromatids during early mitosis.

Chromatid

One half of a duplicated chromosome.

Sister Chromatids

Identical copies of a chromosome held together at the centromere.

Homologous Chromosomes

Chromosome pairs with genes for the same traits.

Crossing Over

Exchange of DNA between non-sister chromatids during Prophase I.

Chiasma

Site where crossing over occurs.

Synapsis

Pairing of homologous chromosomes during Prophase I.

Tetrad

Structure of 4 chromatids formed during synapsis.

Independent Assortment

Random alignment of homologs in Metaphase I.

Random Fertilization

Any sperm can fertilize any egg, increasing diversity.

Diploid (2n)

Cell with two sets of chromosomes.

Haploid (n)

Cell with one set of chromosomes.

Nondisjunction

Error in chromosome separation during meiosis.

Metaphase Plate

Imaginary plane where chromosomes line up during metaphase.