Cell Cycle

actin

The protein that forms microfilaments in the cytoskeleton and aids in cell movement and cytokinesis.

anaphase

The stage of mitosis when sister chromatids separate and move toward opposite poles.

anchorage dependence

The requirement that a cell must be attached to a solid surface to divide.

aster

A radial array of short microtubules extending from the centrosome during mitosis.

Bacteria

Single-celled prokaryotic organisms that reproduce by binary fission.

benign tumor

A mass of abnormal cells that remains at its original site and does not spread.

binary fission

A form of asexual reproduction in which a single cell divides into two identical daughter cells.

cell cycle

The ordered sequence of events in the life of a cell, including interphase and cell division.

cell cycle control system

A set of molecules that triggers and coordinates key events in the cell cycle.

cell division

The process by which a parent cell divides into two or more daughter cells.

cell plate

A structure that forms during cytokinesis in plant cells to divide the cytoplasm.

centromere

The region where sister chromatids are joined together.

centrosome

The structure that organizes microtubules and helps form the mitotic spindle.

checkpoint

A control point in the cell cycle where stop and go-ahead signals regulate progression.

chromatin

The complex of DNA and proteins that makes up chromosomes.

chromosome

A threadlike structure made of DNA and proteins that contains genetic information.

cleavage

The process of cytokinesis in animal cells, characterized by the formation of a cleavage furrow.

cleavage furrow

A shallow groove in the cell surface near the old metaphase plate where cytokinesis occurs in animal cells.

cyclin

A regulatory protein that accumulates and degrades during the cell cycle, activating Cdks.

cyclin-dependent kinase (Cdk)

An enzyme that, when combined with cyclin, regulates the cell cycle by phosphorylating proteins.

cytokinesis

The division of the cytoplasm to form two separate daughter cells after mitosis.

density-dependent inhibition

The phenomenon in which crowded cells stop dividing.

Down syndrome

A genetic disorder caused by the presence of an extra copy of chromosome 21.

G0 phase

A nondividing state in which a cell has left the cell cycle.

G1 phase

The first gap phase in interphase; the cell grows and carries out normal functions.

G2 phase

The second gap phase in interphase; the cell prepares for mitosis.

gamete

A reproductive cell (sperm or egg) that contains a haploid set of chromosomes.

genome

All the genetic material of an organism or cell.

growth factor

A protein that stimulates other cells to divide.

interphase

The period of the cell cycle between divisions when the cell grows, performs normal functions, and duplicates DNA.

kinetochore

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

malignant tumor

A cancerous tumor that invades surrounding tissues and can metastasize.

metaphase

The stage of mitosis when chromosomes align at the metaphase plate.

metaphase plate

An imaginary plane midway between the spindle’s poles where chromosomes align during metaphase.

metastasis

The spread of cancer cells to locations distant from their original site.

mitosis

The division of the nucleus into two genetically identical nuclei.

mitotic (M) phase

The phase of the cell cycle that includes mitosis and cytokinesis.

mitotic spindle

A structure made of microtubules that separates chromosomes during mitosis.

origin of replication

The specific site where DNA replication begins on a chromosome.

prometaphase

The stage of mitosis when the nuclear envelope breaks down and spindle fibers attach to kinetochores.

prophase

The first stage of mitosis when chromatin condenses and the mitotic spindle begins to form.

S phase

The synthesis phase of interphase when DNA is replicated.

sister chromatids

Two identical copies of a chromosome connected by a centromere.

somatic cell

Any body cell except a gamete; contains two sets of chromosomes (diploid).

telophase

The final stage of mitosis when chromosomes reach opposite poles and new nuclei form.

transformation

The process by which a normal cell becomes a cancerous cell.