Cell Division and the Cell Cycle

Comprehensive vocabulary flashcards covering cell growth, prokaryotic binary fission, the eukaryotic cell cycle, the stages of mitosis, cytokinesis differences, ploidy, and cell cycle regulation.

Binary Fission

A form of asexual reproduction and cell division occurring in prokaryotic cells (bacteria) that produces two identical cells through circular DNA replication, membrane addition, inward pushing, cell wall formation, and splitting.

Asexual Reproduction

Reproduction of an organism in which one original organism makes an identical copy of itself.

Sexual Reproduction

Reproduction of an organism achieved by combining genetic material from two different individuals of different sexes.

Plasmids

Separate chunks of circular DNA located in prokaryotic cells apart from the single looped main chromosome.

Surface Area to Volume Ratio

A cellular ratio that decreases as a cell grows because volume increases much faster than surface area (cell membrane), limiting nutrient intake and waste removal and triggering cell division.

Cell Cycle

The life span of a cell during which it grows, replicates DNA, prepares for division, reproduces, and undergoes programmed cell death.

Interphase

The longest part of the cell cycle where cells typically spend approximately $90\%$ of their time growing and preparing for division; divided into $G_1$, $S$, and $G_2$ phases.

Gap 1 ($G_1$) Phase

The first growth phase of interphase during which the cell carries out routine functions, grows in size, and synthesizes new proteins and organelles within a well-defined nucleus surrounded by the nuclear envelope.

Synthesis ($S$) Phase

The sub-phase of interphase in which DNA is replicated (copied) in preparation for cell division.

Gap 2 ($G_2$) Phase

The second growth phase of interphase where the cell prepares for division by assembling microtubules and other required organelles or molecules.

Mitosis

A 4-stage process in eukaryotic cells in which two identical nuclei are created, each possessing an identical set of chromosomes.

Cytokinesis

The physical splitting of a parent cell into two separate daughter cells, each with its own nucleus and DNA.

Centrioles

Cytoskeletal structures found only in animal cells, composed of nine triplets of microtubules, that play a key role in developing mitotic spindle fibers.

Spindle Fibers

Elongations of centrioles that make up the mitotic spindle and function to align and separate chromosomes during cell division.

Chromosomes

Structures located in the nucleus of eukaryotic cells made up of DNA containing many genes tightly wound around proteins such as histones.

Gene

A specific segment of DNA located on a chromosome that codes for a particular protein.

Histones

Proteins associated with eukaryotic DNA that help package it and keep it tightly coiled into chromosomes.

Sister Chromatids

Identical copies of a chromosome formed by DNA replication that remain joined together at the centromere.

Centromere

The central region of a chromosome that serves as the junction point holding sister chromatids together.

Chromatin

The loose, uncoiled, and dispersed immature form of chromosomal DNA in which a eukaryotic cell's genome exists for the majority of its life.

Prophase

The first phase of mitosis during which the nuclear envelope breaks down, chromosomes condense and become visible, centrioles migrate to opposite poles, and the mitotic spindle forms.

Metaphase

The second phase of mitosis during which centrioles are positioned at opposite cell poles, and chromosomes align along the cell's equator and attach to spindle fibers.

Anaphase

The third phase of mitosis characterized by the shortening of spindle fibers and separation of centromeres, pulling chromatids apart toward opposite poles.

Telophase

The fourth phase of mitosis in which the nuclear envelope reforms, chromosomes uncoil into chromatin, spindle fibers withdraw, and the cell membrane begins to cleave.

Cleavage Furrow

The shallow groove formed when the animal cell membrane pinches inward during telophase and cytokinesis to divide the cell into two.

Cell Plate

A structure that develops between the two nuclei of a dividing plant cell during telophase, forming a new cell wall to separate the daughter cells.

Preprophase Band

A structure formed by microtubules in plant cells just before prophase that helps establish and orient the mitotic spindle.

Somatic Cells

All body cells in an organism except sperm and egg cells; these diploid cells divide via mitosis for growth and tissue repair.

Gametes

Specialized haploid sex cells (eggs and sperm) produced through meiosis for sexual reproduction.

Diploid ($2n$)

A cell or organism containing two complete sets of chromosomes, one from each parent (equaling $46$ chromosomes in humans).

Haploid ($n$)

A cell containing a single set of unpaired chromosomes (equaling $23$ chromosomes in human gametes).

Meiosis

A form of cell division that occurs exclusively in germ cells to produce gametes by reducing the original chromosome number by half.

Cancer

A condition caused by a malfunctioning cell cycle where mutated regulatory genes fail to properly control cell growth and timing, leading to uncontrolled division.