Plant Cell Cycle

• Plant Cell Cycle (Mitosis and Meiosis) is governed by the continuous generation of new cells through cell expansion and cell division.
• Chromosomes are thread-like structures in a cell’s nucleus that are visible under the microscope only during cell division.
• Chromosomes consist of proteins and a single large molecule of DNA that contains hundreds of thousands of different genes.
• The number of chromosomes within a nucleus varies from one species to another, but every somatic cell in an organism of a given species contains a characteristic number of chromosomes.
• Homologous chromosomes are members of a chromosome pair that are similar in size, shape, and genetic constitution.
• Homologous chromosomes carry information governing the same genetic traits, although it is not necessarily identical.
• Diploid cells have two sets of chromosomes, while haploid cells have one set of chromosomes.
• The cell cycle is the successive series of events in the life of a dividing eukaryotic cell.
• The cell cycle is often represented as a circle and consists of two main phases: interphase and M phase.
• The period between two successive divisions, represented by a complete revolution of the circle, is the generation time.
• Meristems are localized areas of the plant body where mitosis and cytokinesis take place most of the time.
• Apical meristems allow the production and subsequent elongation of new cells, causing an increase in the length of growing stems and roots.
• Lateral meristems produce additional wood and bark tissues that add girth to stems and roots of trees and shrubs.
• Interphase is the stage between successive cell divisions.
• During interphase, the cell synthesizes needed materials and grows.
• Chromosomes undergo duplication during interphase, a process that is not readily visible.
• Interphase consists of four subphases: Gap I Phase (GI Phase) or Pre-synthesis gap, Synthesis phase (S Phase), Gap II (GII Phase) or Post-synthesis, and Gap Zero Phase (G0).
• DNA Replication is a process of duplicating DNA through semi-conservative replication.
• Transcription is the genetic information in the DNA is transferred to RNA through the catalytic action of RNA polymerase.
• Translation is the synthesis of a protein from an mRNA template.
• Proteins, which are used for millions of cellular functions, are synthesized during interphase.
• M Phase (Mitosis or Meiosis) indicates or signals the completion of interphase.
• Visible changes associated with the division of the nucleus take place during M Phase.
• Most cellular activities, such as Protein synthesis, are suspended during M Phase.
• M Phase is divided into four stages: Prophase, Metaphase, Anaphase, and Telophase.
• Meiosis separates the members of each homologous pair of chromosomes, resulting in four haploid cells.
• Spindle is the structure consisting mainly of microtubules that provides the framework for chromosome movement during cell division.
• Cytokinesis in plant cells is the division of the cytoplasm that usually accompanies mitosis, generally begins during telophase, and occurs by the formation of a cell plate, a partition between the newly formed nuclei in the equatorial region of the cell, forming two daughter cells.
• Vesicles are small, membrane-enclosed sacs.
• The spindle microtubules grow and shrink as they move toward the center of the cell in a “search and capture” process.
• Microtubules function in chromosome distribution during mitosis.
• During prophase, duplicated chromosomes condense and become visible, chromatin begins to condense and coil into visible chromosomes, chromosomes become shorter and thicker and are individually visible under a light microscope, and each chromosome is a duplicated chromosome, consisting of sister chromatids.
• The nucleolus shrinks and disappears during prophase.
• Telophase is the final stage of mitosis when chromosomes arrive at the poles and return to their interphase condition, the chromosomes begin to elongate by uncoiling and then become invisible chromatin threads, and two separate nuclei form.
• pair of chromosomes, resulting in four haploid cells.
• Kinetochore is the portion of the chromosome centromere to which the mitotic spindle fibers attach.
• Anaphase begins as the sister chromatids separate, chromosomes move toward the poles during anaphase, and this phase ends when all the chromosomes have reached the poles.
• After the cells separate the chromosomes and build new nuclei, they divide their cytoplasm by cytokinesis and form two distinct cells.
• Mitosis is a carefully controlled process that organizes and separates the chromosomes correctly.
• Gametes are reproductive cells which have half the diploid number of chromosomes, form a complete, new organism by uniting, and a fertilized egg is produced upon union of the female gamete (egg) and the male gamete (sperm cell).