| A | B |
|---|
| autosome | a chromosome that is not a sex chromosome |
| centromere | a region of the chromosome where the two sister chromatids are held together and which is the site of attachment of the chromosome to the spindle fibers during mitosis |
| chromatid | one of two identical parts of a chromosome |
| chromatin | the DNA and proteins in the nucleus of a nondividing cell |
| chromosome | DNA and protein in a coiled, rod-shaped form that occurs during cell division |
| DNA | hereditary information in the form of a large molecule called deoxyribonucleic acid |
| histone | a protein molecule that DNA wraps around during chromosome formation |
| nonhistone | a protein molecule that controls specific regions of DNA |
| diploid | a cell that contains both chromosomes of a homologous pair |
| haploid | having only one chromosome of each homologous pair |
| homologous chromosome | one of a pair of morphologically similar chromosomes: they are the same size, same shape and they carry the genes for the same traits |
| nucleus in a eukaryotic cell | the organelle that contains most of the DNA and directs most of the cell's activities |
| karyotype | a picture of an individual's chromosomes |
| sex chromosome | a chromosome that determines whether an organism is male or female |
| binary fission | an asexual cell division of prokaryotes that produces identical offspring |
| cell cycle | the events of cell division: includes interphase, mitosis and cytokinesis |
| mitosis | the process of nuclear division that maintains the number of chromosomes in a cell |
| meiosis | the process of nuclear division that reduces the number of chromosomes in a cell by half |
| prokaryote | a unicellular organism that lacks a nucleus and membrane bound organelles |
| prophase | the first stage of mitosis and meiosis, characterized by condensation of chromosomes |
| metaphase | the second phase of mitosis, during which all the chromosomes move the the cell's equator |
| anaphase | a phase of mitosis and meiosis in which the chromosomes separate |
| telophase | the final stage of mitosis during which a nuclear membrane forms around each set of new chromosomes |
| interphase | a period of cell growth and development that precedes eukaryotic cell nuclear division |
| G1 phase | the first period of interphase, in which the cell doubles in size |
| G2 phase | the final period of interphase in which the cell undergoes rapid growth and prepares mitosis |
| S phase | the second period of interphase during which replication of DNA occurs |
| G0 phase | a phase of the cell cycle in which the cell is not dividing and its DNA is not replicating |
| centrosome | a dark body containing a centriole in animal cells but not in plant cells, spindlie fibers radisate fromt he centrosome in preparation for mitosis |
| kinetochore | a disk-shaped protein found in the cnetromere region of a chromosome and attaches the chromosomes to the mitotic spindle |
| polar fiber | a spindle fiber that extends from centrosome to centrosome |
| kinetochore fiber | a spindle fiber that extends from the centrsoome at one pole of the cell to a chromatid during mitosis |
| cell plate | a membrane that divides newly forming plant cells during mitosis |
| cleavage furrow | the area of the cell membrane that pinches in an eventually spearates the dividing cell |
| spindle fiber | one of the microtubules that extend across a dividing eukaryotic cell; assists in the movement of chromosomes |
| mitotic spindle | the array of spindle fibers that serve to divide the chromatids during nuclear division |
| cytokinesis | the division of the cytoplasm of one cell into two new cells |
| asexual reproduction | the production of offspring that does not invovle the union of gametes |
| crossing over | the exchange of genes by reciprocal segments of homologous chromosomes during meiosis |
| gamete | a reproductive cell, sperm or egg |
| genetic recombination | the new mixture of genetic material that is created after crossing-over occurs during prophase I of meiosis |
| oogenesis | the production of mature egg cells |
| polar body | one of two small cells produced and discarded uring each of the two meiotic divisions that yield the haploid cells |
| sexual reproduction | the production of offspring from the combination of genetic material from two parent organisms |
| spermatid | in meiosis, a haploid cell that develops into a mature sperm cell |
| spermatogenesis | the production of sperm cells |
| synapsis | the pairing of homologous chromosomes during meiosis |
| tetrad | a group of two homologous chromosomes during meiosis |
| independent assortment | a random separation of the amterna land paternal chromosomes which results in genetic variation |
