| Alternation of generations |
Cycle of diploid, asexual, vegetative generation alternating with the haploid, sexual generation. |
| Anaphase |
Third phase of mitosis; the sister chromatids separate (now chromosomes) and the centromeres divide, pulling the chromosomes to opposite poles. |
| Antipodal cells |
Three cells sequestered at the opposite end of the mature female gametophyte from the egg and synergid cells. |
| Cell cycle |
Cycle which cells go through in their lifetime; consists of interphase and mitosis. |
| Centromere |
Constricted spot where sister chromatids attach. |
| Chiasma |
Point where sister chromatids of homologs lay over each other, forming an “X” shape. |
| Chromosome |
Structure within the nucleus of a cell that contains the genes; made up of DNA that has looped around histone proteins and then coils and folds. |
| Crossing over |
Exchange of arms of DNA between sister chromatids of homologous chromosomes that can take place at the point of chiasma formation. |
| Cytokinesis |
Occurs directly after telophase; the cell plate forms between the two daughter cells and the cell walls separate the newly formed cells. |
| Diploid |
Term used for zygote cells, where the cell has two sets of chromosomes; abbreviated 2n. |
| DNA |
Basic biochemical compound that makes up the gene. |
| G1 stage of interphase |
First stage of interphase; “G” stands for Gap/Growth. |
| G2 stage of interphase |
Third and final stage of interphase; “G” stands for Gap/Growth. |
| Genetic code |
Order of the four different combinations of the bases in DNA; AT, TA, GC, or CG. |
| Haploid |
Term used for gamete cells that typically contain one set of each of the chromosomes; abbreviated n. |
| Histone protein |
Protein around which the DNA surrounds. |
| Homologous chromosomes (homologs) |
Matching chromosomes from the two different sets; carry the genetic information that affects the same characteristic or function at the same location on the chromosome; from sperm and egg cells. |
| Interphase |
One of the two major parts of the cell cycle; consists of G1, S, and G2 stages. |
| Kinetochore |
Point of attachment of the spindle and the centromere. |
| Metaphase |
Second stage of mitosis; the spindle fibers grow and form attachments to the pairs of sister chromatids at the centromeres. |
| Metaphase plate |
Equatorial plate formed along the midline of the cell between the poles. |
| Nucleosome |
Made up of eight histone proteins and wrapped by a segment of DNA. |
| Ploidy |
Number of sets of homologous chromosomes in a cell. |
| Polar nuclei |
Two haploid nuclei contained within one cell membrane in the mature female gametophyte. One sperm cell will unite with these two polar nuclei to establish the triploid endosperm tissue. |
| Prophase |
First stage of mitosis; chromatin begins to coil and condense to form chromosomes. |
| Purine |
Consists of the base pairs Adenine and Guanine and contains two rings of carbon atoms. |
| Pyrimidine |
Consists of the base pairs Cytosine and Thymine and contains one ring of carbon atoms. |
| Ribose-phosphate backbone |
Chain of alternating ribose and phosphate that make up the sides of the DNA structure. |
| S stage of interphase |
Second stage of interphase where the chromosomes replicate (DNA replicated). |
| Sister chromatids |
Two chromosomes that are exact copies and are created during the S stage of interphase. |
| Somatic cells |
Cells of flowering plants, other than the reproductive cells; always 2n. |
| Spindle apparatus |
Microtubules associated with movement of the chromosomes during division. |
| Sporangia |
Structures in the androecium and gynoecium where meiosis takes place and the gametophyte generation develops. |
| Spore |
Haploid single cell produced by meiosis in the sporangium of a diploid sporophyte. |
| Telophase |
Fourth and final stage of mitosis; the nuclear membrane forms around the chromosomes in each of the daughter cells. |
| Tetrads |
Groupings of four sister chromatids. |
| Triploid |
Term used for endosperm that has three sets of chromosomes; abbreviated 3n. |
