AP Biology: Mitosis, Cell Cycle, and Meiosis

Vocabulary practice flashcards covering cell cycle regulation, mitosis, cytokinesis, and meiosis mechanisms from AP Biology Reading Guides 4.2 and 4.3.

Genome

The complete set of DNA instructions for an organism.

Chromosomes

The structures into which DNA is packaged in a cell to prepare for cell division.

Chromatin

The loose, uncoiled form of DNA when it is not packaged into condensed chromosomes.

Histones

Proteins around which DNA winds to provide structure and organization.

Somatic cells

Diploid ($2n$) body cells (such as skin, brain, and stomach cells) that contain a full set of chromosomes ($46$ in humans) and divide by mitosis.

Gametes

Haploid ($n$) sex cells (sperm and eggs) containing half a set of chromosomes ($23$ in humans) that are produced through meiosis.

Sister chromatids

Identical copies of a single replicated chromosome joined together at the centromere.

Centromere

The constricted region of a duplicated chromosome that holds sister chromatids together.

Kinetochore

A protein complex assembled on the centromere where spindle fibers attach during cell division.

Cell cycle

A highly regulated series of events for the growth and reproduction of cells.

Interphase

The growth and preparation stage of the cell cycle consisting of $G_1$, $S$, and $G_2$ phases.

$G_1$ phase

The first gap phase of interphase characterized by intense cell growth.

$S$ phase

The synthesis phase of interphase in the nucleus where DNA is replicated, doubling chromatids from $46$ to $92$.

$G_2$ phase

The final subphase of interphase where the cell undergoes final growth and preparation for division.

Mitosis

The process that ensures the transfer of a complete genome from a parent cell to two genetically identical daughter cells.

Prophase

The first stage of mitosis where the nuclear envelope begins to disappear, chromatin coils into visible chromosomes, and spindle fibers appear.

Metaphase

The stage of mitosis where spindle fibers align chromosomes along the equatorial plate (metaphase plate) in the middle of the cell.

Anaphase

The stage of mitosis where spindle fibers pull sister chromatids apart into individual chromosomes ($92$ total) toward opposite poles.

Telophase

The stage of mitosis where separated chromosomes reach opposite poles, nuclear envelopes reform around each set, and chromosomes begin to uncoil.

Cytokinesis

The division of the cytoplasm following mitosis to form two distinct daughter cells.

Cell plate

A structure that forms during plant cell cytokinesis due to rigid cell walls, eventually developing into the cell wall between daughter cells.

Cleavage furrow

A shallow groove formed by animal cell membranes pinching inward during cytokinesis.

$G_1$ checkpoint

A cell cycle checkpoint occurring at the end of $G_1$ before the $S$ phase that evaluates cell size, nutrients, growth factors, and DNA damage.

$G_2$ checkpoint

A checkpoint at the end of $G_2$ before mitosis that verifies DNA replication completion and checks for DNA damage.

M checkpoint (Spindle checkpoint)

A regulatory checkpoint between metaphase and anaphase that checks for proper spindle fiber attachment to chromosome kinetochores.

Cyclins

A group of related proteins whose concentrations fluctuate throughout specific phases of the cell cycle to regulate progression.

Cyclin-dependent kinases (CDKs)

Enzymes that regulate the cell cycle by phosphorylating target proteins when bound to an activating cyclin.

MPF (Maturation-promoting factor)

A cyclin-CDK complex that triggers the cell's passage past the $G_2$ checkpoint into mitosis.

Density-dependent inhibition

The regulatory phenomenon in normal cells where crowded conditions cause them to stop dividing.

Anchorage dependence

The requirement that normal cells must be attached to a substratum or solid surface to divide and grow.

Meiosis

A specialized cell division in sexually reproducing organisms that reduces chromosome number by half, yielding four genetically diverse haploid daughter cells.

Gene

A portion of DNA that codes for a specific protein.

Locus

The specific physical location of a gene on a chromosome.

Zygote

The diploid ($2n$) cell produced by the fusion of sperm and egg that subsequently undergoes mitosis to develop into an organism.

Autosomes

Chromosomes that are identical in both males and females and do not determine biological sex.

Sex chromosomes

Chromosomes ($\text{X}$ and $\text{Y}$) that determine the biological sex of an individual ($\text{XX}$ in females, $\text{XY}$ in males).

Homologous chromosomes

A pair of chromosomes carrying genes for the same inherited characteristics at matching loci.

Tetrad

A paired structure consisting of four chromatids formed by synapsed homologous chromosomes during meiosis.

Meiosis I

The first division of meiosis that separates homologous chromosome pairs into two haploid cells.

Meiosis II

The second division of meiosis that separates sister chromatids into individual chromosomes.

Independent assortment

The random orientation and distribution of maternal and paternal homologous chromosome pairs at the metaphase plate during metaphase I.

Crossing over

The physical connection and reciprocal exchange of genetic segments between non-sister chromatids of homologous chromosomes, creating recombinant chromatids.

Random fertilization

The random union of any sperm with any ovum, generating novel genetic combinations with approximately $70\text{ trillion}$ possible diploid outcomes.