16 - Cell Division and Mitosis

zygote

a cell formed by the union of two gametes; the first cell of a new individual

genome

all of the genetic material of a cell or organism

gamete

haploid reproductive cell (sperm or egg) that fuses with another haploid cell during fertilization

diploid

cell, nucleus, or organism containing two sets of chromosomes (2n)

haploid

cell, nucleus, or organism containing one set of chromosomes (n)

homologous chromosome

chromosomes of the same morphology with the same genes in the same location; diploid organisms have pairs of homologous chromosomes (homologs), with each homolog derived from a different parent

gene

segment of DNA that codes for a functional molecule (usually, a protein)

locus

position of a gene on a chromosome

cell cycle

ordered series of events involving cell growth and cell division that produces two new daughter cells

interphase

period of the cell cycle leading up to mitosis; includes G1, S, and G2 phases (the interim period between two consecutive cell divisions)

mitotic phase

period of the cell cycle during which duplicated chromosomes are distributed into two nuclei and cytoplasmic contents are divided; includes karyokinesis (mitosis) and cytokinesis

cytokinesis

division of the cytoplasm following mitosis that forms two daughter cells

G1 phase

first phase of interphase centered on cell growth during mitosis

S phase

second, or synthesis, stage of interphase during which DNA replication occurs

G2 phase

third phase of interphase during which the cell undergoes final preparations for mitosis

mitotic spindle

apparatus composed of microtubules that orchestrates the movement of chromosomes during mitosis

G0 phase

a quiescent phase outside of the cell cycle

karyokinesis

division of the nucleus into two daughter nuclei

prophase

stage of mitosis during which chromosomes condense and the mitotic spindle begins to form

microtubules

polymers of tubulin proteins that form long fibers; part of the cytoskeleton. Helps the cell resist compression, provides a track along which vesicles move through the cell, pulls replicated chromosomes to opposite ends of a dividing cell, and is the structural element of centrioles, flagella, and cilia

prometaphase

stage of mitosis during which the nuclear membrane breaks down and mitotic spindle fibers attach to kinetochores

sister chromatid

one of the two identical copies that makes up half of a duplicated chromosome

kinetochore

protein structure associated with the centromere of each sister chromatid that attracts and binds spindle microtubules during prometaphase

centromere

region at which sister chromatids are bound together

metaphase

stage of mitosis during which chromosomes are aligned at the metaphase plate

anaphase

stage of mitosis during which sister chromatids are separated from each other

telophase

stage of mitosis during which chromosomes arrive at opposite poles, decondense, and are surrounded by a new nuclear envelope