| A | B |
|---|
| 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 |
| 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 |
| cloning | a process in which a cell, cell product, or organism is copied from an orginal source |
| mutation | a permanent transmissible change of genetic material (eg chromosomal mutations and gene mutations) |
| nondisjunction | the process in which sister chromatids fail to separate during and after mitosis or meiosis |
