binary fission

asexual reproduction of a cell by division into two equal, or nearly equal, parts (bacteria)

chromosome

the vehicle by which hereditary information is physically transmitted from one generation to the next. In a eukaryotic cell, long threads of DNA that are associated with protein and that contain hereditary information

mitosis

the M phase of cell division in which the microtubular apparatus is assembled, binds to the chromosomes, and moves them apart. This phase is essential step in the separation of the two daughter cell genomes; mechanism of cell division that occurs in an or

meiosis

a special form of nuclear division that precedes gamete formation in sexually reproducing eukaryotes. it results in four haploid daughter cells; divides the DNA in cells that participate in sexual reproduction, or germ cells.

complex cell cycle

the events that prepare the eukaryotic cell for division and the division process itself constitute a _____ ____ ____.

interphase

the portion of the cell cycle preceding mitosis. it includes the G1 phase, when cells grow, the S phase, when a replica of the genomes is synthesized, and for G2 phase, when preparations are made for genomic separation

G1 phase

the "first gap" phase is the cell's primary growth phase. For most organisms, this phase occupies the major portion of the cell's life span

S phase

synthesis" phase, the DNA replicates, producing two copies of each chromosome

G2 phase

cell division preparation continues in the "second gap" phase with the replication of mitochondria, chromosome condensation, and the synthesis of microtubules

M phase

in mitosis, a microtubular appartus binds to the chromosomes and moves them apart

C phase

in cytokinesis, the cytoplasm divides, creating two daughter cells

homologous chromosomes

one of the two nearly identical versions of each chromosome. chromosomes that associate in pairs in the first stage of meiosis, in diploid cels, one chromosome of a pair that carries equivalent genes

homologues

carry information about the same traits at the same locations on each chromosome but the information can vary between ____.

diploid cells

a cell, tissue, or individual with a double set of chromosomes

sister chromatids

before cell division, each homologous chromosome replicates, resulting in two identical copies

centromere

a constricted region of the chromosome joining two sister chromatids, to which the kinetochore is attached

chromatin

one of the two daughter strands of a duplicated chromosome that is joined by a single centromere

histones

a complex of small, very basic polypeptides rich in the amino acids arginine and lysine. a basic part of chromosomes, ____ form the core around which DNA is wrapped

nucleosome

the basic packaging unit of eukaryotic chromosomes, in which the DNA molecule is wound around a ball of histone proteins. Chromatin is composed of long strings of nucleosomes, like beads on a string

condensation

the coiling of the chromosomes into more and more tightly compacted bodies begun during the G2 phase of the cell cycle

prophase

the first stage of mitosis during which the chromosomes become more condensed, the nuclear envelope is reabsorbed, and the network of microtubles (called the spindle) forms between opposite poles of the cell

spindle

a network of of protein cables

metaphase

the stage of mitosis characterized by the alignment of the chromosomes on a plane in the center of the cell

anaphase

in mitosis and meiosis II, the stage initiated by the separation of sister chromatids, during with the daughter chromosomes move to opposite poles of the cell; in meiosis I, marked by separation of replicated homologous chromosomes

telophase

the nuclear envelope reappears. the chromosomes decondense. as _____ progresses, cytokinesis also occurs

karyokinesis

also referred to as mitosis, division of the nucleus

cytokinesis

the C phase of cell division in which the cell itself divides, creating two daughter cells

growth factors

cell division is initiated by small proteins called _____ ____. work by binding to the plasma membrane and triggering intracellular signaling systems

cancer

unrestrained invasive cell brother. a tumor or cell mass resulting from uncontrollable cell division

tumor

cluster of cells constantly expanding in size

metastases

cells that leave a tumor and spread throughout the body, forming new tumors at distant sites

mutation

a change in a cell's genetic message

proto-oncogenes

encode proteins that stimulate cell division

oncogenes

mutated proto-oncogenes become cancer-causing genes

tumor-suppressor genes

second class of cancer causing genes. cell division is normally turned off in healthy cells by proteins encoded by _____ ____ _____.

gametes

a haploid reproductive cell. upon fertilization, its nucleus fuses with that of another gamete of the opposite sex. the resulting diploid cell (zygote) may develop into a new diploid individual, or in some protists and fungi, may undergo meiosis to form h

zygote

the diploid cell resulting from the fusion of male and female gametes(fertilization)

fertilization

the union of male and female gametes to form a zygote

syngamy

fertilization. the unction of male and female gametes

diploid

a cell, tissue, or individual with a double set of chromosomes

haploid

the gametes of a cell or an individual with only one set of chromosomes

sexual reproduction

reproduction that involves the regular alternation between syngamy and meiosis. its outstanding characteristic is that an individual offspring inherits genes from two parent individuals

asexual reproduction

reproducing without forming gametes. ____ ____ does not involve sex. its outstanding characteristic is that an individual offspring is genetically identical to its parent

somatic

all the diploid body cells of animal that are not involved in gamete formation

germ-line

the cells that will eventually undergo meiosis to produce gametes are set aside from somatic cells early in the course of development

meiosis I

the first of the two divisions of meiosis; serves to separate the two versions of each chromosome

meiosis II

the second of the two divisions of meiosis; serves to separate the two replica of each version, called sister chromatids

crossing over

DNA is exchanged between the two non sister chromatids of homologous chromosomes

metaphase I

the chromosomes align on a central plane

independent assortment

Mendel's second law: the principle that segregating of alternative alleles at one locus into gametes is independent of the segregation of alleles at other loci. Only true for gene loci located on different chromosomes or those so far apart on one chromoso

anaphase I

one homologue with its two sister chromatids still attached moves to a pole of the cell, and the other homologue moves to the opposite pole

telophase I

individual chromosomes gather together at each of the two poles

synapsis

the close pairing of homologous chromosomes that occurs early in prophase I of meiosis. with the genes of the chromosomes thus aligned, a DNA strand of one homologue can pair with the complementary DNA strange of the other