Chapter 13: Terms

Chapter 13 flashcards

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.



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