diploid
describes a cell, nucleus, or organism containing two sets of chromosomes (2n)
A somatic cell contains two matched sets of chromosomes, a configuration known as diploid.
gamete
a haploid reproductive cell or sex cell (sperm or egg)
Human cells that contain one set of 23 chromosomes are called gametes, or sex cells; these eggs and sperm are designated n, or haploid.
gene
the physical and functional unit of heredity; a sequence of DNA that codes for a specific peptide or RNA molecule
Homologous chromosomes are the same length and have specific nucleotide segments called genes in exactly the same location, or locus.
genome
the entire genetic complement (DNA) of an organism
A cell’s complete complement of DNA is called its genome.
haploid
describes a cell, nucleus, or organism containing one set of chromosomes (n)
Human cells that contain one set of 23 chromosomes are called gametes, or sex cells; these eggs and sperm are designated n, or haploid.
homologous chromosomes
chromosomes of the same length with genes in the same location; diploid organisms have pairs of homologous chromosomes, and the members of each pair come from different parents
The matched pairs of chromosomes in a diploid organism are called homologous chromosomes.
locus
the position of a gene on a chromosome
Homologous chromosomes are the same length and have specific nucleotide segments called genes in exactly the same location, or locus.
anaphase
the stage of mitosis during which sister chromatids are separated from each other
Mitosis is divided into a series of phases—prophase, prometaphase, metaphase, anaphase, and telophase—that result in the division of the cell nucleus (Figure 6.4).
cell cycle
the ordered sequence of events that a cell passes through between one cell division and the next
The continuity of life from one cell to another has its foundation in the reproduction of cells by way of the cell cycle.
cell cycle checkpoints
mechanisms that monitor the preparedness of a eukaryotic cell to advance through the various cell cycle stages
To prevent a compromised cell from continuing to divide, there are internal control mechanisms that operate at three main cell cycle checkpoints at which the cell cycle can be stopped until conditions are favorable.
cell plate
a structure formed during plant-cell cytokinesis by Golgi vesicles fusing at the metaphase plate; will ultimately lead to formation of a cell wall to separate the two daughter cells
There, the vesicles fuse from the center toward the cell walls; this structure is called a cell plate.
centriole
a paired rod-like structure constructed of microtubules at the center of each animal cell centrosome
The centrosome consists of a pair of rod-like centrioles at right angles to each other.
cleavage furrow
a constriction formed by the actin ring during animal-cell cytokinesis that leads to cytoplasmic division
This fissure, or “crack,” is called the cleavage furrow.
cytokinesis
the division of the cytoplasm following mitosis to form two daughter cells
The second portion of the mitotic phase, called cytokinesis, is the physical separation of the cytoplasmic components into two daughter cells.
G0 phase
a cell-cycle phase distinct from the G1 phase of interphase; a cell in G0 is not preparing to divide
Cells in the G0 phase are not actively preparing to divide.
G1 phase
(also, first gap) a cell-cycle phase; first phase of interphase centered on cell growth during mitosis
The first stage of interphase is called the G1 phase, or first gap, because little change is visible.
G2 phase
(also, second gap) a cell-cycle phase; third phase of interphase where the cell undergoes the final preparations for mitosis
In the G2 phase, or second gap, the cell replenishes its energy stores and synthesizes the proteins necessary for chromosome manipulation.
interphase
the period of the cell cycle leading up to mitosis; includes G1, S, and G2 phases; the interim between two consecutive cell divisions
The cell cycle has two major phases: interphase and the mitotic phase (Figure 6.3).
kinetochore
a protein structure in the centromere of each sister chromatid that attracts and binds spindle microtubules during prometaphase
The kinetochore becomes attached to the mitotic spindle.
metaphase plate
the equatorial plane midway between two poles of a cell where the chromosomes align during metaphase
The kinetochore becomes attached to metaphase plate.
metaphase
the stage of mitosis during which chromosomes are lined up at the metaphase plate
Mitosis is divided into a series of phases—prophase, prometaphase, metaphase, anaphase, and telophase—that result in the division of the cell nucleus (Figure 6.4).
mitosis
the period of the cell cycle at which the duplicated chromosomes are separated into identical nuclei; includes prophase, prometaphase, metaphase, anaphase, and telophase
The two centrosomes will give rise to the mitotic spindle, the apparatus that orchestrates the movement of chromosomes during mitosis.
mitotic phase
the period of the cell cycle when duplicated chromosomes are distributed into two nuclei and the cytoplasmic contents are divided; includes mitosis and cytokinesis
The cell cycle has two major phases: interphase and the mitotic phase (Figure 6.3).
mitotic spindle
the microtubule apparatus that orchestrates the movement of chromosomes during mitosis
The two centrosomes will give rise to the mitotic spindle, the apparatus that orchestrates the movement of chromosomes during mitosis.
prometaphase
the stage of mitosis during which mitotic spindle fibers attach to kinetochores
Mitosis is divided into a series of phases—prophase, prometaphase, metaphase, anaphase, and telophase—that result in the division of the cell nucleus (Figure 6.4).
prophase
the stage of mitosis during which chromosomes condense and the mitotic spindle begins to form
Mitosis is divided into a series of phases—prophase, prometaphase, metaphase, anaphase, and telophase—that result in the division of the cell nucleus (Figure 6.4).
quiescent
describes a cell that is performing normal cell functions and has not initiated preparations for cell division
The cell is in a quiescent (inactive) stage, having exited the cell cycle.
S phase
the second, or synthesis phase, of interphase during which DNA replication occurs
In the S phase (synthesis phase), DNA replication results in the formation of two identical copies of each chromosome—sister chromatids—that are firmly attached at the centromere region.
telophase
the stage of mitosis during which chromosomes arrive at opposite poles, decondense, and are surrounded by new nuclear envelopes
Mitosis is divided into a series of phases—prophase, prometaphase, metaphase, anaphase, and telophase—that result in the division of the cell nucleus (Figure 6.4).
oncogene
a mutated version of a proto-oncogene, which allows for uncontrolled progression of the cell cycle, or uncontrolled cell reproduction
Proto-oncogenes are normal genes that, when mutated, become oncogenes—genes that cause a cell to become cancerous.
proto-oncogene
a normal gene that controls cell division by regulating the cell cycle that becomes an oncogene if it is mutated
The genes that code for the positive cell-cycle regulators are called proto-oncogenes.
tumor suppressor gene
a gene that codes for regulator proteins that prevent the cell from undergoing uncontrolled division
Tumor suppressor genes are genes that code for the negative regulator proteins, the type of regulator that—when activated—can prevent the cell from undergoing uncontrolled division.
binary fission
the process of prokaryotic cell division
Prokaryotes such as bacteria propagate by binary fission.
origin
the region of the prokaryotic chromosome at which replication begins
The starting point of replication, the origin, is close to the binding site of the chromosome to the plasma membrane (Figure 6.9).
septum
a wall formed between bacterial daughter cells as a precursor to cell separation
A septum is formed between the nucleoids from the periphery toward the center of the cell.
FtsZ
a tubulin-like protein component of the prokaryotic cytoskeleton that is important in prokaryotic cytokinesis (name origin: Filamenting temperature-sensitive mutant Z)
The formation of a ring composed of repeating units of a protein called FtsZ directs the partition between the nucleoids in prokaryotes.
These terms were extracted from Concepts of Biology – 1st Canadian Edition by Charles Molnar and Jane Gair, eCampusOntario (originally published by BCcampus) which is licensed under a Creative Commons Attribution 4.0 International License. Chapter content adapted from Concepts of Biology by OpenStax (© Rice University), licensed under CC BY 4.0.