Chapter 9 Vocab

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

Anchorage Dependence

The requirement that a cell must be attached to a substratum in order to initiate cell division

Aster

The radical array of short microtubules that extends from each centrosome toward the plasma membrane in an animal cell undergoing mitosis

Benign tumor

A mass of abnormal cells with specific genetic and cellular changes such that the cells are not capable of surviving at a new site and generally remain at the site of the tumors origin

Binary Fission

A method of asexual reproduction in single-celled organisms in which the cell grows to roughly double its size and then divides into two cells. In prokaryotes, binary fission does not involve mitosis, but in single-celled eukaryotes that undergo binary fission, mitosis is part of the process

Cell Cycle

An ordered sequence of event sin the life of a cell, from its origin in the division of a parent cell until its own division into two. The eukaryotic cell cycle is composed of interphase (including G1, S, G2 subphases) and M phase (including mitosis and cytokinesis)

Cell cycle control system

A cyclically operating set of molecules in the eukaryotic cell that both triggers and coordinates key events in the cell cycle

Cell Division

The reproduction of cells

Cell plate

A membrane-bounded, flattened sac located at the midline of a dividing plant cell, inside which the new cell wall forms during cytokinesis

Centromere

In a duplicated chromosome, the region on each sister chromatid where it is most closely attached to its sister chromatid 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.)

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.

Checkpoint

A control point in the cell cycle where stop and go-ahead signals can regulate the cycle

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.

Chromosome

A cellular structure consisting of one DNA molecule and associated protein molecules. (In some contexts, such as genome sequencing, the term maybe refer to the DNA alone) A eukaryotic cell typically has multiple, linear chromosomes, which are located in the nucleus. A prokaryotic cell often has a single, circular chromosome, which is found in the nucleoid, a region that is not enclosed by a membrane

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.

Cleavage Furrow

The first sing of cleavage in an animal cell; a shallow groove around the cell in the cell surface near the old metaphase plate.

Cyclin

a family of regulatory proteins that control the progression of the cell cycle

Cytokinesis

The division of the cytoplasm to form two separate daughter cells immediately after mitosis, meiosis I, or meiosis II

Density- dependent inhibition

The phenomenon observed in normal animal cells that causes them to stop dividing when they come into contact with one another

G0 phase

A nondividing state occupied by cells that have left the cell cycle, sometimes reversibly

G1 phase

The first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins

G2 phase

The second gap, or growth phase, of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs

Gamete

A haploid reproductive cell, such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote.

Genome

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.

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.

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.

Kinetochore

A structure of proteins attached to the centromere that links each sister chromatid to the mitotic spindle

Malignant 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

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.

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.

Metastasis

The spread of cancer cells to locations distant from their original site.

Mitosis

A process of nuclear division in eukaryotic cells conventionally divided into 5 stages: prophase, prometaphase, metaphase, anaphase, and telophase. Mitosis conserves chromosome number by allocating replicated chromosomes equally to each of the daughter nuclei.

Mitotic (M) phase

The phase of the cell cycle that includes mitosis and cytokinesis

Mitotic spindle

An assemblage of microtubules and associated proteins that is involved in the movement of chromosome during mitosis.

Origin of replication

Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides.

Prometaphase

The second stage of mitosis, in which the nuclear envelope fragments and the spindle microtubules attach to the kinetochore of the chromosomes.

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 nucleus disappears but the nucleus remains intact.

S phase

The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated

Sister chromatids

Two copies of a duplicated chromosome attached to each other by proteins 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.

Somatic cell

Any cell in a multicellular organism except a sperm or egg or their precursors.

Telophase

The fifth and final stage of mitosis, in which daughter nuclei are forming and cytokinesis has typically begun.

Transformation

(1) The process by which a cell in culture acquires the ability to divide indefinitely, similar to the division of cancer cells. (2) A change in genotype and phenotype due to assimilation of external DNA is from a member of different species, transformation results in horizontal gene transfer.