IBP 1 Test 5

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

Genome: total genetic information of a cell or organism

Gene: physical and functional unit of heredity, a sequence of DNA that codes for a protein.

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

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

Gamete: haploid reproductive cell or sex cell (sperm, pollen grain, or egg)

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

Histone: one of several similar, highly conserved, low molecular weight, basic proteins found in the chromatin of all eukaryotic cells; associates with DNA to form nucleosomes

Nucleosome: subunit of chromatin composed of a short length of DNA wrapped around a core of histone proteins

Centromere: region at which sister chromatids are bound together; a constricted area in condensed chromosomes

Chromatid: single DNA molecule of two strands of duplicated DNA and associated proteins held together at the centromere

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

G1 phase: (also, first gap) 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: (also, second gap) third phase of interphase during which the cell undergoes final preparations for mitosis

G0 phase: distinct from the G1 phase of interphase; a cell in G0 is not preparing to divide

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

Mitosis: (also, karyokinesis) period of the cell cycle during which the duplicated

chromosomes are separated into identical nuclei; includes prophase, prometaphase, metaphase, anaphase, and telophase

Mitotic spindle: apparatus composed of microtubules that orchestrates the movement of chromosomes during mitosis

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

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

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

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

Metaphase plate: equatorial plane midway between the two poles of a cell where the

chromosomes align during metaphase

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

Cytokinesis: division of the cytoplasm following mitosis that forms two daughter cells.

Cleavage furrow: constriction formed by an actin ring during cytokinesis in animal cells that leads to cytoplasmic division

Cell plate: structure formed during plant cell cytokinesis by Golgi vesicles, forming a temporary structure (phragmoplast) and fusing at the metaphase plate; ultimately leads to the formation of cell walls that separate the two daughter cells

Cell-cycle checkpoint: mechanism that monitors the preparedness of a eukaryotic cell to advance through the various cell-cycle stages

Cyclin: one of a group of proteins that act in conjunction with cyclin-dependent kinases to help regulate the cell cycle by phosphorylating key proteins; the concentrations of cyclins fluctuate throughout the cell cycle

Cyclin-dependent kinase (Cdk): one of a group of protein kinases that helps to regulate the cell cycle when bound to cyclin; it functions to phosphorylate other proteins that are either activated or inactivated by phosphorylation

Proto-oncogene: normal gene that when mutated becomes an oncogene

Oncogene: mutated version of a normal gene involved in the positive regulation of the cell cycle

Tumor suppressor gene: segment of DNA that codes for regulator proteins that prevent the cell from undergoing uncontrolled division

p53: cell-cycle regulatory protein that regulates cell growth and monitors DNA damage; it halts the progression of the cell cycle in cases of DNA damage and may induce apoptosis

p21: cell-cycle regulatory protein that inhibits the cell cycle; its levels are controlled by p53

Binary fission: prokaryotic cell division process

FtsZ: tubulin-like protein component of the prokaryotic cytoskeleton that is important in prokaryotic cytokinesis (name origin: Filamenting temperature-sensitive mutant Z)

Septum: structure formed in a bacterial cell as a precursor to the separation of the cell into two daughter cells

Zygote: fertilized egg cell formed by the union of two haploid gametes

Sexual reproduction: reproductive process in which two haploid cells fuse to form a

genetically unique diploid cell

Meiosis: a nuclear division process that results in four haploid cells

Ploidy: number of chromosome sets contained in a cell or nucleus

Meiosis I: first round of meiotic cell division; referred to as reduction division because the ploidy level is reduced from diploid to haploid

Reduction division: nuclear division that produces daughter nuclei each having one-half as many chromosome sets as the parental nucleus; meiosis I is a reduction division

Meiosis II: second round of meiotic cell division following meiosis I; sister chromatids are separated into individual chromosomes, and the result is four unique haploid cells

Genetic variation: differences in genetic composition among cells or individuals

Prophase I: first stage of meiosis I during which homologous chromosomes pair, synapsis and crossover occur, and the chromosomes condense