Biology Unit 4 Vocab

anaphase

anaphase

Third stage of mitosis, beginning when sister chromatids separate from each other and ending when a complete set of daughter chromosomes has arrived at each of two poles of the cell.

asexual reproduction

The creation of genetically identical offspring by a single parent, without the participation of gametes (sperm and egg).

autosome

A chromosome not directly involved in determining the sex of an organism; in mammals, for example, any chromosome other than X or Y.

benign tumor

An abnormal mass of cells that remains at its original site in the body.

cancer

A malignant growth or tumor caused by abnormal and uncontrolled cell division.

cell cycle

An ordered sequence of events (including interphase and the mitotic phase) that extends from the time a eukaryotic cell is first formed from a dividing parent cell until its own division into two cells.

cell division

The reproduction of a cell.

cell plate

A membranous disk that forms across the midline of a dividing plant cell. During cytokinesis, the cell plate grows outward, accumulating more cell wall material and eventually fusing into a new cell wall.

centromere

The region of a chromosome where two sister chromatids are joined and where spindle microtubles attach during mitosis and meiosis. The ___________ divides at the onset of anaphase during mitosis and anaphase II.

chemotherapy

Treatment for cancer in which drugs are administered to disrupt cell division of the cancer cells.

chiasma

microscopically visible site where crossing over has occured between chromatids of homologous chromosomes during prophase I of meiosis.

chromosome

A gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis; also, the main gene-carrying structure of a prokaryotic cell. Each __________ consists of one very long threadlike DNA molecule and associated proteins.

cleavage furrow

The first sign of cytokinesis during cell division in an animal cell; a shallow groove in the cell surface near the old metaphase plate.

crossing over

The exchange of segments between chromatids of homologous chromosomes during prophase I of meiosis.

cytokinesis

The division of the cytoplasm to form two separate daughter cells. ___________ usually occurs during telophase of mitosis, and the two processes (mitosis and ______________) make up the mitotic (M) phase of the cell cycle.

diploid

Containing two sets of chromosomes (pairs of homologous chromosomes) in each cell, one set inherited from each parent; referring to a 2n cell.

Down Syndrome

A human genetic disorder resulting from a condition called trisomy 21, the presence of an extra chromosome 21; characterized by heart and respiratory defects and varying degrees of mental retardation.

fertilization

The union of a haploid sperm cell with a haploid egg cell, producing a zygote.

gamete

A sex cell; a haploid egg sperm. The union of two __________ of opposite sex (fertilization) produces a zygote.

genetic recombination

The production of offspring with gene combinations that differ from that found in either parent.

haploid

containing a single set of chromosomes; referring to an n cell.

histone

A small protein molecule associated with DNA and important in DNA packing in the eukaryotic chromosome.

homologous chromosome

The two chromosomes that make up a matched pair in a diploid cell. _are of the same length, possess genes for the same characteristics at corresponding loci. One _ is inherited from the organisms father, the other from the mother.

interphase

The phase in the eukaryotic cell cycle when the cell is not actually dividing. During __________, cellular metabolic activity is high, chromosomes and organelles are duplicated, and cell size may increase. Interphase accounts for 90% of the cell cycle.

karyotype

A display of micrographs of the metaphase chromosomes of a cell, arranged by size and centromere position.

life cycle

The entire sequence of stages in the life of an organism, from the adults of one generation to the adults of the next.

malignant tumor

An abnormal tissue mass that spreads into neighboring tissue and to other parts of the body; a cancerous tumor.

meiosis

In a sexually reproducing organism, the process of cell division that produces haploid gametes from diploid cells within the reproductive organs.

metaphase

The second stage of mitosis. During _____________, the centromeres of all the cell's duplicated chromosomes are lined up on an imaginary plate equidistant between the poles of the mitotic spindle.

metastasis

The spread of cancer cells beyond their original site.

mitosis

The division of a single nucleus into two genetically identical daughter nuclei. ________ and cytokinesis make up the mitotic (M) phase of the cell cycle.

mitotic spindle

A spindle-shaped structure formed of microtubles and associated proteins that is involved in the movement of chromosomes during mitosis and meiosis. (A spindle is shaped roughly like a football).

nondistjunction

An accident of meiosis or mitosis in which a pair of homologous chromosomes or a pair of sister chromatids fail to separate at anaphase.

prophase

The first stage of mitosis. During ________, duplicated chromosomes condense to form structures visible with a light microscope, and the mitotic spindle forms and begins moving the chromosomes toward the center of the cell.

radiation therapy

Treatment for cancer in which parts of the body that have cancerous tumors are exposed to high-energy radiation to disrupt cell division of the cancer cells.

sex chromosome

A chromosome that determines whether an individual is male or female; in mammals, for example, the x or y chromosome.

sexual reproduction

The creation of genetically distinct offspring by the fusion of two haploid sex cells (gametes; sperm and egg), forming a diploid zygote.

sister chromatid

one of the two indentical parts of a duplicated chromosome while joined, two __________ make up one chromosome; chromatids are eventually separated druing mitosis or meiosis II.

somatic cell

Any cell in a multicellular organism except a sperm or egg cell or a cell that develops into a sperm or egg; a body cell.

telophase

The fourth and final stage of mitosis, during which daughter nuclei form at the two poles of a cell. _______ usually occurs together with cytokinesis.

tumor

An enlargement at the end of a rhizome, in which food is stored.

zygote

The fertilized egg, which is diploid, that results from the union of haploid gametes (sperm and egg) during fertilization.