Vocabulary

anaphase

the fourth phase of mitosis in which sister chromatids separate and are pulled to the opposite poles of the cell

astral microtubule

spindle fiber that attaches the centrosome to the cell membrane

binary fission

the process by which prokaryotic cells divide; asexual reproduction

cell cycle

the life of a cell, from its beginning to the time when it divides to produce a new cell

cell division

the process by which one cell divides and becomes two new cells

cell equator

an imaginary line in the center of a cell during mitosis, along which sister chromatids align

cell-cycle-control system

a series of checkpoints directed by chemical signals in a cell that regulate cell growth and division

centromere

the point on a chromosome that attaches to the spindle fibers during cell division and at which sister chromatids are attached

centrosome

a structure in the cytoplasm of animal cells that coordinates the formation of microtubules, which allows cell division to proceed during reproduction

chromatid

one of two identical halves of a replicated chromosome

cleavage furrow

the indentation in an animal cell along which cytokinesis occurs

cohesin

a protein that helps bind sister chromatids together at the centromere

cyclin

regulatory molecule that functions as a gatekeeper, along with Cdks, to move a cell past checkpoints in the cell cycle

cyclin-dependent kinase (Cdk)

regulatory molecule (usually a protein) that functions as a gatekeeper, along with cyclins, to move a cell past checkpoints in the cell cycle

cytokinesis

the pinching off of the cytoplasm to form two new cells

G1 phase

the first phase of the cell cycle; when a cell grows

G2 phase

the third phase of the cell cycle; when a cell grows

interphase

collectively the G1, S, and G2 phases of mitosis; in which a cell grows, replicates its DNA, and grows again

interpolar microtubule

spindle fiber that extends from the centrosome across the cell equator

kinetochore

a group of proteins bound at the centromere to which the spindle fibers attach

kinetochore microtubule

spindle fiber that extends from the centrosome to the kinetochore on the centromere

M phase

the fourth phase of the cell cycle; when a cell divides

metaphase

the third phase of mitosis, in which the sister chromatids line up along the cell equator

mitosis

the process of cell division that results in two cells that are genetic clones of the parent cell

mitotic spindle

bundle of spindle fibers attached at one end to the centrosome

origin of replication

the place on a prokaryotic chromosome where DNA replication begins

prometaphase

the second phase of mitosis in which the nuclear membrane breaks down and spindle fibers attach to the centromere

prophase

the first phase of mitosis in which sister chromatids condense, the mitotic spindle begins to form, and centrosomes segregate to opposite poles

S phase

the second phase of the cell cycle when DNA is replicated

vesicle

a small, leftover piece of the nuclear membrane