Cell Cycle and Mitosis

Vocabulary practice flashcards covering cell cycle phases, prokaryotic binary fission, chromosome structure, ploidy, stages of mitosis, mitotic spindle components, and differences between animal and plant cytokinesis.

Cell Cycle

The life cycle of a cell involving growth, DNA replication, and cell division.

Binary Fission

The prokaryotic cell division process where a single circular chromosome replicates and is pulled apart as the plasma membrane constricts and a new cell wall forms between daughters.

$G_1$ Phase

The first gap phase of interphase during which the cell grows and synthesizes various RNAs, proteins, and cellular molecules before DNA replication.

$S$ Phase

The synthesis phase of interphase during which the cell replicates its DNA and chromosomal proteins to create a duplicated copy of each chromosome.

$G_2$ Phase

The second gap phase of interphase where there is no DNA synthesis; the cell continues growing and produces RNAs and proteins required for mitosis, marking the end of interphase.

$G_0$ Phase

A quiescent cell cycle arrest state outside the replicative cycle where mature cells undergo terminal differentiation or remain temporarily until re-entry into division.

Sister Chromatids

Two identical copies of a replicated chromosome that remain physically attached to each other at the centromere.

Centromere

The constricted chromosomal region that physically links sister chromatids and serves as the assembly site for kinetochores.

Kinetochore

A large protein complex assembled at the centromere of each sister chromatid where spindle microtubules attach.

Haploid ($1n$)

A cell or organism containing only one set of chromosomes ($n$).

Diploid ($2n$)

A cell or organism containing two complete sets of chromosomes ($2n$), with one homologous set inherited from the mother and one from the father.

Homologous Chromosomes

A pair of corresponding maternal and paternal chromosomes in a diploid cell that match in shape and carry the same gene loci.

Nucleosome

A fundamental subunit of chromatin consisting of histone proteins organized into a complex around which eukaryotic DNA winds.

Prophase

The initial phase of mitosis in which chromatin condenses into visible chromosomes, the nuclear envelope begins breaking down, and the mitotic spindle starts to form.

Prometaphase

The stage of mitosis where the nuclear envelope breaks down completely and spindle microtubules search and capture kinetochores to move chromosomes toward the midzone.

Metaphase

The stage of mitosis where replicated chromosomes are attached to bipolar spindle microtubules and align along the metaphase plate.

Anaphase

The mitotic stage during which sister chromatids separate into daughter chromosomes and migrate toward opposite spindle poles.

Anaphase A

The component of anaphase during which kinetochore microtubules shorten via depolymerization, transporting chromatids poleward.

Anaphase B

The component of anaphase during which non-kinetochore microtubules slide past one another to push the poles apart and elongate the spindle.

Telophase

The final stage of nuclear division (karyokinesis) where chromosomes decondense, the mitotic spindle disassembles, and nuclear envelopes reform around daughter nuclei.

Cytokinesis

The process dividing the cytoplasm of a parental cell to produce two independent daughter cells, typically beginning in late anaphase or telophase.

Kinetochore Microtubules

Spindle fibers that attach to kinetochores at their plus ($+)$) ends and function to orient and move chromosomes toward opposite poles.

Non-kinetochore Microtubules

Spindle fibers that overlap in the spindle midzone without attaching to chromosomes, maintaining spindle structural integrity and mediating spindle elongation.

Astral Microtubules

Microtubules present only in animal spindles that extend outward from the centrosomes to control spindle positioning and pole distance.

Acentrosomal Spindles

Mitotic spindles formed in plant cells that lack centrosomes and consequently display broader spindle poles.

Cleavage Furrow

A groove that forms in animal cells as a contractile ring of microfilaments constricts the plasma membrane inward from outside to inside.

Contractile Ring

A band of actin filaments and myosin-II filaments assembled beneath the plasma membrane that constricts like a drawstring during animal cytokinesis.

Cell Plate

A structure formed in dividing plant cells through the fusion of Golgi vesicles at the spindle midzone that grows outward from inside to outside to build the new cell wall.