Chp 3 Mitosis Meiosis Plant Cycle

• The cell cycle in plants describes the events of the cell cycle and compares and contrasts mitosis and meiosis.
• Growth is dictated by the continuous generation of new cells through cell expansion and cell division.
• Telomeres are thread-like structures in a cell’s nucleus that are visible under the microscope only during cell division and consist of proteins and a single large molecule of DNA that contains hundreds of thousands of different genes.
• During Meiosis, the maternal and paternal chromosomes of homologous pairs separate independently so that each member of a pair is randomly distributed to one of the poles at anaphase.
• A Comparison of Mitosis and Meiosis
• The importance of Plant Cell Cycle: Mitosis and Meiosis is discussed in a video.
• 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 and carry information governing the same genetic traits, although it is not necessarily identical.
• Diploid cells have two chromosomes represented by 2n, while haploid cells have a single set of chromosomes represented by n.
• The cell cycle is the successive series of events in the life of a dividing eukaryotic cell, 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, occurring in the shoot and root tips (the apical meristems) and in some plants, in thin cylindrical regions that run the entire lengths of stems and roots except at the tips (the lateral meristems).
• Apical meristems allow the production and subsequent elongation of new cells, causing an increase to 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.
• Interphase: “between phases”
• During interphase, the cell synthesizes needed materials and grows.
• Chromosomes undergo duplication during interphase, but this duplication is not readily visible.
• Interphase has three subphases: Gap I Phase (GI Phase) or Pre-synthesis gap, Synthesis phase (S Phase), and Gap II (GII Phase) or Post-synthesis.
• The first gap phase (G1) is the first stage in Interphase and is a pre-synthesis phase where the cell grows and duplication of organelles occurs.
• The synthesis phase (S) is the second stage of Interphase where the duplication of the nucleus and synthesis of DNA and protein occur.
• The secondary gap phase (G2) is the third step, next to S Phase, and is a post-synthesis phase that allows the cells to grow more and prepares the cell for the actual division (M Phase).
• Gap zero phase (G0) is also known as the resting phase, where cells may opt to enter this phase or may directly enter the G1 phase up to cell division.
• Intrinsic and extrinsic factors such as resource availability and nutritional deprivation can cause cells to enter the G0 phase temporarily or permanently.
• DNA replication is a process of duplicating DNA through semi-conservative replication.
• Transcription is the genetic information in the DNA being 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 translation.
• Mitosis indicates or signals the completion of interphase and visible changes associated with the division of the nucleus take place.
• Most cellular activities, such as cell division, occur during the M Phase.
• Protein synthesis is suspended during the G1 phase of the cell cycle.
• The G1 phase of the cell cycle is divided into four stages: Prophase, Metaphase, Anaphase, and Telophase.
• M Phase: Mitosis facilitates plant growth and repair through mitotic cell division.
• M Phase: Mitosis is a mechanism that maintains the equal distribution of chromosome content, producing two identical cells from a single parent cell.
• M Phase: Mitosis involves a nuclear division (karyokinesis) that involves condensation and separation of replicated chromosomes.
• M Phase: Mitosis is divided into four stages: Prophase, Metaphase, Anaphase, and Telophase.
• Mitosis: Prophase is the stage where 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 light microscope.
• Each chromosome in Mitosis: Prophase is a duplicated chromosome, consisting of sister chromatids.
• Centromere is a specialized region of a chromosome.
• Sister chromatids are joined in the vicinity of their centromeres during prophase.