36 terms

Mitosis

How does cell reproduction perpetuate life? In multicellular organisms individual cells grow and then divide via a process called mitosis. The cell cycle is an ordered set of events, resulting in cell growth and division into two daughter cells. Organisms begin as a single cell (fertilized egg) that divides successively to produce many cells
STUDY
PLAY
Cell Cycle
An ordered sequence of events in the life of a cell
Mitosis
A process of nuclear division in eukaryotic cells conventionally divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase. Mitosis conserves chromosome number by allocating replicated chromosomes equally to each of the daughter nuclei.
Prophase
The first stage of mitosis, in which the chromatin condenses into discrete chromosomes visible with a light microscope, the mitotic spindle begins to form, and the nucleolus disappears but the nucleus remains intact.
Prometaphase
The second stage of mitosis, in which the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the chromosomes.
Metaphase
The third stage of mitosis, in which the spindle is complete and the chromosomes, attached to microtubules at their kinetochores, are all aligned at the metaphase plate.
Anaphase
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.
Telophase
The fifth and final stage of mitosis, in which daughter nuclei are forming and cytokinesis has typically begun.
Cytokinesis
The division of the cytoplasm to form two separate daughter cells immediately after mitosis, meiosis I, or meiosis II.
Cell Division
The reproduction of cells
Chromosomes
A cellular structure carrying genetic material, found in the nucleus of eukaryotic cells. Each chromosome consists of one very long DNA molecule and associated proteins
Chromatin
The complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope
Gametes
A haploid reproductive cell, such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote.
Sister Chromatids
Two copies of a duplicated chromosome attached to each other by proteis at the centromere and sometimes, along the arms. While joined, two sister chromatids make up one chromosome. Chromatids are eventually separated during mitosis or meiosis II
Centromere
In a duplicated chromosome, the region on each sister chromatid where they are most closely attached to each other by proteins that bind to specific DNA sequences; this close attachment causes a constriction in the condensed chromosome. (An uncondensed, unduplicated chromosome has a single centromere, identified by its DNA sequence.)
mitotic (M) phase
The phase of the cell cycle that includes mitosis and cytokinesis.
interphase
The period in the cell cycle when the cell is not dividing. During interphase, cellular metabolic activity is high, chromosomes and organelles are duplicated, and cell size may increase. Interphase often accounts for about 90% of the cell cycle.
aster
A radial array of short microtubules that extends from each centrosome toward the plasma membrane in an animal cell undergoing mitosis.
cleavage
(1) The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane. (2) The succession of rapid cell divisions without significant growth during early embryonic development that converts the zygote to a ball of cells.
growth factor
(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.
kinetochore
A structure of proteins attached to the centromere that links each sister chromatid to the mitotic spindle.
tumor
A cancerous tumor containing cells that have significant genetic and cellular changes and are capable of invading and surviving in new sites. Malignant tumors can impair the functions of one or more organs.
Metaphase plate
An imaginary structure located at a plane midway between the two poles of a cell in metaphase on which the centromeres of all the duplicated chromosomes are located.
asexual reproduction
A type of reproduction involving only one parent that produces genetically identical offspring by budding or by the division of a single cell or the entire organism into two or more parts.
sexual reproduction
A type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from the gametes of the two parents.
diploid cell
A cell containing two sets of chromosomes (2n), one set inherited from each parent.
haploid cell
A cell containing only one set of chromosomes (n).
Meiosis
Meiosis is essential to sex, because it enables each parent to contribute one set of chromosomes-- half the total-- to each diploid offspring.
G1 Phase
The first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins.
S Phase
The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.
G2 Phase
The second gap, or growth phase, of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs.
Centrosome
A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division. A centrosome has two centrioles.
Cleavage Furrow
The first sign of cleavage in an animal cell; a shallow groove around the cell in the cell surface near the old metaphase plate.
Cell Plate
A new cell wall forms during cytokinesis in the middle of a plant cell
Cell cycle
A cyclically operating set of molecules in the eukaryotic cell that both triggers and coordinates key events in the cell cycle.
Checkpoint
A control point in the cell cycle where stop and go-ahead signals can regulate the cycle.
G0 Phase
A nondividing state occupied by cells that have left the cell cycle, sometimes reversibly.