BioScience Dictionary

 
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Ot.

Found Prophase 18 times.

Displaying results 1 to 10.

1. Aster
A star-shaped structure, composed of microtubule s, which surrounds the centriole s during mitosis in animals. The aster forms during prophase . The spindle fiber s arise gradually between the two asters (at opposite ends of the cell ) until they attach to the kinetochore s of the centromere s of each chromosome. Asters are not found in vascular plant cells.

2. Bivalent (tetrad)
A pair of homologous chromosome s which have joined together (are synaps ed) during prophase I and metaphase I of meiosis .

3. Crossing-over
During the first meiotic prophase , the process in which part of a chromatid is physically exchanged with another chromatid to form chromosomes with new allele combinations.

4. Diplotene
A substage of the prophase I stage of meiosis , a type of nuclear division, during which chiasmata (points where the arms of homologous chromosome s cross over each other, just before recombination occurs) can be seen.

5. First meiotic division
The first of two consecutive divisions of the nucleus of an eukaryotic cell during the process of meiosis . It includes the following stages of meiosis: prophase I , metaphase I , anaphase I , and telophase I .

6. Germinal vesicle
The nucleus of a primary oocyte , the development of which is suspended in prophase I of the first meiotic division between embryohood and sexual maturity.

7. Metaphase
The stage in mitosis just after prophase during which the chromosome s are aligned along a single plane in the center of the cell . This stage is the briefest stage of mitosis. Each chromosome can clearly be observed as a pair of joined, identical chromatid s. The stage ends as soon as the centromere s connecting the pairs to each other break.

8. Metaphase I
The stage in the first meiotic division of meiosis that follows prophase I . Homologous chromosome s pair with each other to form tetrad s of four chromatid s and they align themselves along a single plane in the center of the cell . Homologous recombination generally occurs during this stage. This stage ends as soon as the homologous chromosomes start being pulled away from each other, to opposite ends of the cell.

9. Metaphase II
The stage in the second meiotic division of meiosis that follows prophase II , during which the chromosome s are aligned along a single plane in the center of each cell produced during the first meiotic division (two total cells). Each chromosome can clearly be observed as a pair of joined, identical chromatid s. The stage ends as soon as the centromere s connecting the pairs to each other break.

10. Mitosis
The division of the cell's nucleus and nuclear material of a cell; consists of four stages: prophase , metaphase , anaphase , and telophase . Cell xeroxing. Mitosis occurs only in eukaryotes . The DNA of the cell is replicated during interphase of the cell cycle and then segregated during the four phases of mitosis.


View web definitions »

Learn more about Prophase »