Lesson 2.1 & 2.2 — Cell Cycle and Cell Division

Comprehensive vocabulary flashcards covering the cell cycle phases, regulation mechanisms, mitosis, meiosis, gametogenesis, and associated chromosomal disorders.

Cell cycle

The sequence of phases in the life of the cell from the beginning of one cell division to the beginning of the next, involving growth and division.

Interphase

The longest phase of the cell cycle where the cell grows, replicates its DNA, and accumulates nutrients in preparation for division.

$G_1$ stage (Gap 1)

The first stage of interphase where the cell increases in size, organelles increase in number, and protein and $mRNA$ are produced at high rates.

$G_0$ stage

A resting stage where cells may become mitotically arrested for days to years, or even permanently as in muscle and nerve cells.

Synthesis (S) stage

A crucial part of interphase characterized by the replication of cellular DNA, resulting in the cell having twice as many chromosomes.

$G_2$ stage (Gap 2)

The final stage of interphase where the cell synthesizes more proteins, such as kinases and histones, and prepares for nuclear division.

Karyokinesis

The process of nuclear division where nuclear materials divide and separate toward opposite ends of the cell.

Cytokinesis

The division of the cell's cytoplasm that occurs near the end of mitosis, producing two new daughter cells.

Maturation promoting factor (MPF)

A protein kinase complex of $CDK1/Cyclin B$ that serves as the master regulator for cells to enter M-phase from $G_2$.

Internal regulators

Proteins found inside the cell that ensure processes like chromosome replication or spindle fiber attachment are complete before moving to the next phase.

External regulators

Proteins or molecular signals, such as growth factors, that respond to events outside the cell to stimulate growth and division.

$G_1/S$ checkpoint

The control point that checks for cell size, nutrient levels, external cues, and the integrity of DNA before committing to synthesis.

$G_2/M$ checkpoint

The control point prior to mitosis that checks for DNA replication damage and triggers repair or apoptosis.

M checkpoint

Also known as the spindle checkpoint, it ensures all sister chromatids are correctly attached to spindle microtubules before anaphase begins.

Cancer

A disease characterized by uncontrolled cell division resulting from a breakdown in cell cycle regulators.

$p53$ gene

A tumor-suppressor gene that monitors DNA integrity; it can halt the cell cycle for repairs or trigger apoptosis if damage is irreparable.

Metastasis

The process by which cancer cells spread from their original site to other healthy tissues or organs.

Apoptosis

Programmed cell death involving shrinkage of chromatin and breakage of the cell membrane, essential for shaping structures during development.

Binary fission

A simpler and faster process of cell division used by prokaryotes like bacteria and archaea.

Mitosis

A type of nuclear division in eukaryotes that results in two daughter cells genetically identical to the parent cell, maintaining the diploid chromosome number.

Prophase

The first phase of mitosis where chromatin coils into chromosomes, the nuclear envelope disappears, and spindle fibers begin to form.

Metaphase

The stage of mitosis where spindle fibers align chromosomes at the equatorial plate.

Anaphase

The stage of mitosis where sister chromatids separate and are pulled toward opposite poles of the cell.

Telophase

The final stage of mitosis where nuclear membranes reform around two sets of chromosomes and chromosomes begin to decondense.

Cleavage furrow

A structure formed in animal cells during cytokinesis by the pinching inward of a contractile ring made of actin and myosin.

Cell plate

A structure formed in plant cells during cytokinesis by Golgi bodies to create a new cell wall between daughter nuclei.

Meiosis

A reduction division that reduces the chromosome number from diploid ($2n$) to haploid ($n$) to produce germ cells.

Synapses

The pairing of homologous chromosomes during Prophase I of meiosis.

Tetrad

A structure formed during meiosis I consisting of four sister chromatids from a pair of homologous chromosomes.

Crossing over

The exchange of genetic material between non-sister chromatids at the chiasma, leading to genetic recombination.

Gametogenesis

The process where diploid cells undergo meiosis and differentiation to form mature haploid gametes.

Spermatogenesis

The process of sperm formation in males, occurring in the seminiferous tubules of the testes.

Oogenesis

The process of egg formation in females, which begins during gestation and resumes at puberty.

Sertoli cells

Cells in the seminiferous tubules that provide nutrients and blood products to nourish immature germ cells.

Down syndrome

A genetic disorder also known as Trisomy $21$, caused by the nondisjunction of chromosome $21$ during meiosis.

Turner syndrome

A rare genetic disorder in females characterized by an $X0$ genotype, resulting in sterility and underdeveloped secondary sex characteristics.

Klinefelter syndrome

A genetic disorder in males characterized by an extra X chromosome ($XXY$), resulting in sterility and some breast development.

Cytologist

A health care professional who specializes in studying cells to determine if they are normal, inflamed, or malignant.

Colchicine

A mitosis-inhibiting drug used to treat gout and in laboratories to arrest cells at metaphase for chromosome evaluation.