General Biology 1: Cell Division and the Cell Cycle

These vocabulary flashcards cover the eukaryotic cell cycle, the specific stages of mitosis and meiosis, chromosomal structures, and clinical disorders resulting from cell division failure, based on the General Biology 1 course materials.

Cell cycle

A continuous sequence of events involving cell growth and division, divided into two major phases: interphase and mitosis.

Somatic cells

Body cells that replicate by means of mitosis.

Gametes

Sex cells that reproduce by means of meiosis.

Interphase

The period of growth and development in the cell cycle consisting of three phases: $G_1$, $S$, and $G_2$.

$G_1$ phase

The first gap phase where the cell grows physically larger, copies organelles, makes molecular building blocks, and synthesizes structural proteins and enzymes.

S phase

The synthesis phase where the cell replicates its DNA, resulting in each chromosome being duplicated into two identical sister chromatids joined at a centromere.

$G_2$ phase

The second gap phase where the cell continues to grow, prepares for mitosis, checks DNA replication success, and forms spindle fibers.

Mitosis

A process of cell division in eukaryotic cells where a parent cell divides to produce two identical daughter cells, ensuring each has an exact copy of the parent DNA.

Prophase (Mitosis)

Phase where chromosomes condense into compact X-shaped bodies, chromatids become visible in pairs, the nuclear membrane disappears, and spindle fibers form.

Prometaphase

Stage where the nuclear envelope breaks down, the mitotic spindle grows and captures chromosomes, and chromosomes become even more condensed.

Metaphase

Stage where microtubules pull chromosomes with equal force to the middle of the cell at a region known as the metaphase plate.

Anaphase

Phase during which sister chromatids separate and are pulled toward opposite poles of the cell by spindle fibers.

Telophase

Final stage of mitosis where nuclear membranes form around each set of chromosomes, chromosomes uncoil, and the mitotic spindle breaks down.

Cytokinesis

The process that follows mitosis where the entire cell divides into two resulting in identical daughter cells.

Tumorigenesis

The process of the formation of a new tumor or tumors involving the transformation of normal cells to a neoplastic state.

Mitotic chromosomal instability

The inability to faithfully segregate equal chromosome complements to two daughter cells during mitosis, a widespread phenomenon in cancer cells.

Aneuploidy

A condition characterized by an abnormal number of chromosomes in a cell, which can lead to developmental abnormalities.

Separase

An enzyme involved in chromosome separation; its deregulation can lead to chromosome nondisjunction.

Chromosome

The structure that carries the basic genetic material DNA; humans have $46$ arranged into $23$ pairs.

Histone

A protein that provides structural support and helps in compacting the long molecules of DNA to fit into the cell nucleus.

Centromere (Kinetochore)

A constriction at the center of chromosomes that serves as an attachment region for spindle fibers to enable movement during anaphase.

Telomere

The terminal region of each side of the chromosome; each chromosome has $2$ which help preserve genetic information.

P arm

The short arm structure of a chromosome.

Q arm

The long arm structure of a chromosome.

Meiosis I

The Reductional Division stage that separates homologous chromosomes and produces two cells with a haploid chromosome number ($N$).

Meiosis II

The Equational division stage where daughter cells maintain the same number of chromosomes as the parent cells that entered this phase.

Crossing over

The process occurring in Prophase I where non-sister chromatids of homologous chromosomes exchange genetic material to produce diversity in species.

Synaptonemal complex

A protein structure that holds homologous chromosomes together during the crossover process.

Leptotene

The first stage of Prophase I where chromosomes begin to condense and connect to the nuclear membrane by their telomeres.

Zygotene

The second stage of Prophase I where a synaptonemal complex forms between homologous chromosomes, a process called synapsis.

Pachytene

The third stage of Prophase I where non-sister chromatids exchange genetic material through crossing over.

Diplotene

The fourth stage of Prophase I where synaptonemal complexes disappear toward the conclusion of synapsis.

Diakinesis

The fifth stage of Prophase I where chromosomes become fully condensed and the nuclear membrane and nucleolus break down.

Random orientation

The mechanism during Metaphase I where homologous pairs line up randomly and independently at the equator, introducing variation into gametes.

Meiotic nondisjunction

A failure where homologous chromosomes or sister chromatids fail to separate properly during meiosis, potentially resulting in conditions like Down syndrome.

Translocation

A meiotic error where a segment of one chromosome becomes attached to another chromosome, which can lead to chronic myelogenous leukemia (CML).

Deletion

An error where part of a chromosome is lost during meiosis, causing disorders such as Cri-du-chat syndrome.

Synapsis

The tight pairing of homologous chromosomes during Metaphase I lineup that supports crossing over and genetic recombination.