Ch. 8 - Cellular Reproduction

Question 1

anaphase

Answer 1

The 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 the two poles of the cell.

Question 2

asexual reproduction

Answer 2

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

Question 3

Autosome

Answer 3

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

Question 4

benign tumor

Answer 4

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

Question 5

cancer

Answer 5

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

Question 6

cell cycle

Answer 6

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.

Question 7

cell cycle control system

Answer 7

A cyclically operating set of proteins that triggers and coordinates events in the eukaryotic cell cycle.

Question 8

cell division

Answer 8

The reproduction of a cell.

Question 9

cell plate

Answer 9

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.

Question 10

centromere

Answer 10

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

Question 11

Centrosome

Answer 11

Material in the cytoplasm of a eukaryotic cell that gives rise to microtubules; important in mitosis and meiosis; functions as a microtubule-organizing center.

Question 12

Chemotherapy

Answer 12

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

Question 13

chiasma

Answer 13

(plural, chiasmata) The microscopically visible site where crossing over has occurred between chromatids of homologous chromosomes during prophase I of meiosis.

Question 14

chromatin

Answer 14

The combination of DNA and proteins that constitutes chromosomes; often used to refer to the diffuse, very extended form taken by the chromosomes when a eukaryotic cell is not dividing.

Question 15

chromosome

Answer 15

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 chromosome consists of one very long threadlike DNA molecule and associated proteins. See also chromatin.

Question 16

cleavage furrow

Answer 16

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

Question 17

cross

Answer 17

The cross-fertilization of two different varieties of an organism or of two different species; also called hybridization.

Question 18

crossing over

Answer 18

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

Question 19

cytokinesis

Answer 19

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

Question 20

diploid

Answer 20

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

Question 21

Down syndrome

Answer 21

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

Question 22

fertilization

Answer 22

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

Question 23

Gamete

Answer 23

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

Question 24

genetic recombination

Answer 24

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

Question 25

haploid

Answer 25

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

Question 26

Histone

Answer 26

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

Question 27

homologous chromosomes

Answer 27

The two chromosomes that make up a matched pair in a diploid cell. Homologous chromosomes are of the same length, centromere position, and staining pattern and possess genes for the same characteristics at corresponding loci. One homologous chromosome is inherited from the organism’s father, the other from the mother.

Question 28

interphase

Answer 28

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

Question 29

karyotype

Answer 29

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

Question 30

life cycle

Answer 30

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

Question 31

malignant tumor

Answer 31

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

Question 32

Meiosis

Answer 32

In a sexually reproducing organism, the division of a single diploid cell into four haploid daughter cells. Meiosis and cytokinesis produce haploid gametes from diploid cells in the reproductive organs of the parents.

Question 33

mitotic (M) phase

Answer 33

The phase of the cell cycle when mitosis divides the nucleus and distributes its chromosomes to the daughter nuclei and cytokinesis divides the cytoplasm, producing two daughter cells.

Question 34

mitotic spindle

Answer 34

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

Question 35

nondisjunction

Answer 35

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

Question 36

nucleosome

Answer 36

The bead-like unit of DNA packing in a eukaryotic cell; consists of DNA wound around a protein core made up of eight histone molecules.

Question 37

radiation therapy

Answer 37

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.

Question 38

Sex chromosome

Answer 38

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

Question 39

Sexual reproduction

Answer 39

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

Question 40

sister chromatid

Answer 40

One of the two identical parts of a duplicated chromosome. While joined, two sister chromatids make up one chromosome; chromatids are eventually separated during mitosis or meiosis II.

Question 41

somatic cell

Answer 41

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.

Question 42

telophase

Answer 42

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

Question 43

trisomy 21

Answer 43

See Down syndrome.

Question 44

tumor

Answer 44

An abnormal mass of cells that forms within otherwise normal tissue.

Question 45

zygote

Answer 45

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

Question 46

prophase

Answer 46

The first stage of mitosis. During prophase, 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.