Chapter 12 Flashcards
The reproduction of cells.
Cell Division
An ordered sequence of events in the life of a cell, from its origin in the division of a parent cell until its own division into two; the eukaryotic ____ _____ is composed of interphase (including G¹, S, and G² subphases) and M phase (including mitosis and cytokinesis).
Cell Cycle
The genetic material of an organism or virus; the complete complement of an organism’s or virus’s genes along with its noncoding nucleic acid sequences.
Genome
A cellular structure carrying genetic material, found in the nucleus of eukaryotic cells. Each consists of one very long DNA molecule and associated proteins. (A bacterial ________ usually consists of a single circular DNA molecule and associated proteins. It is found in the nucleoid region, which is not membrane bounded.)
Chromosome
Any cell in a multicellular organism except a sperm or egg.
Somatic Cell
A haploid reproductive cell, such as an egg or sperm. They unite during sexual reproduction to produce a diploid zygote.
Gamete
Either of two copies of a duplicated chromosome attached to each other by proteins at the centromere and, sometimes, along the arms. While joined, two of them make up one chromosome; chromatids are eventually separated during mitosis or meiosis II.
Sister Chromatid
The specialized region of the chromosome where two sister chromatids are most closely attached.
Centromere
The complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing, _______ exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope.
Chromatin
A process of nuclear division in eukaryotic cells conventionally divided into 5 stages: prophase, prometaphase, metaphase, anaphase, and telophase. _______ conserves chromosome number by allocating replicated chromosomes equally to each of the daughter nuclei.
Mitosis
The division of the cytoplasm to form two separate daughter cells immediately after mitosis, meiosis I, or meiosis II.
Cytokinesis
A modified type of cell division in sexually reproducing organisms consisting of two rounds of cell division but only one round of DNA replication. It results in cells with half the number of chromosome sets as the original cell.
Meiosis
The phase of the cell cycle that includes mitosis and cytokinesis.
Mitotic (M) Phase
The period in the cell cycle when the cell is not dividing. Cellular metabolic activity is high, chromosomes and organelles are duplicated, and cell size may increase. Accounts for 90% of the cell cycle.
Interphase
The first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins.
G1 Phase
The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.
S phase
The second gap, or growth phase, of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs.
G2Phase
The first stage of mitosis, in which the chromatin condenses, the mitotic spindle begins to form, and the nucleolus disappears, but the nucleus remains intact.
Prophase
The second stage of mitosis, in which the discrete chromosomes consisting of identical sister chromatids appear, the nuclear envelope fragments, and the spindle microtubules attach to the kinetochores of the chromosomes.
Prometaphase
The third stage of mitosis, in which the spindle is complete and the chromosomes, attached to microtubues at their kinetochores, are all aligned at the metaphase plate.
Metaphase
The fourth stage of mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell.
Anaphase
The fifth and final stage of mitosis, in which daughter nuclei are forming and cytokinesis has typically begun.
Telophase
An assemblage of microtubules and associated proteins that is involved in the movements of chromosomes during mitosis.
Mitotic Spindle
Structure present in the cytoplasm of animal cells, important during cell division; functions as a microtubule-organizing center. Has two centrioles.
Centrosome
A structure of proteins attached to the centromere that links each sister chromatid to the mitotic spindle.
Kinetochore
An imaginary plane midway between the two poles of a cell in metaphase on which the centromeres of all the duplicated chromosomes are located.
Metaphase Plate
A radial array of short microtubules that extends from each centrosome toward the plasma membrane in an animal cell undergoing mitosis.
Aster
The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane.
Cleavage
The first sign of cleavage in an animal cell; a shallow groove in the cell surface near the old metaphase plate.
Cleavage Furrow
A double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis.
Cell Plate
A method of asexual reproduction by “division in half.” In prokaryotes, ______ ______ does not involve mitosis; but in single-celled eukaryotes that undergo ______ ______, mitosis is part of the process.
Binary Fissioin
Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides.
Origin of Replication
A cyclically operating set of molecules in the eukaryotic cell that both triggers and coordinates key events in the cell cycle.
Cell Cycle Control System
A control point in the cell cycle where stop and go-ahead signals can regulate the cycle.
Checkpoint
A cellular protein that occurs in a cyclically fluctuating concentration and that plays an important role in regulating the cell cycle.
Cyclin
A protein kinase that is active only when attached to a particular cyclin.
Cyclin-Dependent Kinase (Cdk)
Maturation-promoting factor (M-phase-promoting factor); a protein complex required for a cell to progress from late interphase to mitosis. The active form consists of cyclin and a protein kinase.
MPF
(1) A protein that must be present in the extracellular environment (culture medium or animal body) for the growth and normal development of certain types of cells. (2) A local regulator that acts on nearby cells to stimulate cell proliferation and differentiation.
Growth Factor
The phenomenon observed in normal animal cells that causes them to stop dividing when they come into contact with one another.
Density-Dependent Inhibition
The requirement that a cell must be attached to a substratum in order to divide.
Anchorage Dependence
(1) The conversion of a normal animal cell to a cancerous cell. (2) A change in genotype and phenotype due to the assimilation of external DNA by a cell.
Transformation
A mass of abnormal cells that remains at the site of its origin.
Benign Tumor
A cancerous tumor that is invasive enough to impair the functions of one or more organs.
Malignant Tumor
The spread of cancer cells to locations distant from their original site.
Metastasis
