Key Concept: All organisms, no matter how large, begin life as a single cell. Growth and reproduction are fundamental characteristics of cells. Cell Growth and Division: A single cell divides and gives rise to two daughter cells. Daughter cells grow and divide further, forming a population of cells. Repeated...
Overview: The cell cycle varies in duration depending on the organism and cell type. Human cells: ~24 hours. Yeast cells: ~90 minutes. Two major phases: Interphase: Preparation for division (95% of the cycle). M Phase (Mitosis Phase): Actual cell division. M Phase (Mitosis Phase): Definition: Phase where the cell...
Overview: M Phase (Mitosis Phase): The most dramatic period of the cell cycle, involving significant reorganization of the cell’s components. It is also called equational division because the number of chromosomes in both the parent and daughter cells remains the same. Though mitosis is divided into four main stages,...
Overview: Prophase is the first stage of karyokinesis in mitosis. It follows the S and G2 phases of interphase, where DNA replication occurs. During S and G2 phases, new DNA molecules are intertwined and not distinct. Prophase is marked by the condensation of chromosomal material and several cellular changes....
Overview: Metaphase is the second stage of mitosis, beginning with the disintegration of the nuclear envelope. By this stage, the condensation of chromosomes is complete, and they are fully visible under a microscope. This stage is where the morphology of chromosomes is most easily studied. Key Events in Metaphase:...
Overview: Anaphase is the stage in mitosis where the sister chromatids (now called daughter chromosomes) separate and begin moving toward opposite poles of the cell. Key Events in Anaphase: Separation of Chromatids: At the onset of anaphase, the centromeres of each chromosome split, and the sister chromatids separate. The...
Overview: Telophase is the concluding stage of nuclear division (karyokinesis) in mitosis. It involves the reorganization and restoration of the nuclear structures at each pole of the cell. Key Events in Telophase: Chromosome Decondensation: Chromosomes that have reached their respective poles decondense and lose their distinct structure. Chromatin material...
Overview: Cytokinesis is the process of cytoplasmic division that follows karyokinesis (nuclear division) to form two daughter cells. It completes the process of cell division by segregating the cytoplasm into two distinct cells. Key Features of Cytokinesis: In Animal Cells: Mechanism: Achieved through the formation of a furrow in...
Overview: Mitosis, also known as equational division, usually occurs in diploid cells but can also occur in haploid cells of some lower plants and social insects. It plays a crucial role in the growth, maintenance, and repair of multicellular organisms. Significance of Mitosis: Genetic Consistency: Produces diploid daughter cells...
Definition: Meiosis is a specialized cell division that reduces chromosome number by half, resulting in the production of haploid daughter cells from diploid cells. It ensures the production of a haploid phase in sexually reproducing organisms, while fertilization restores the diploid phase. Occurs during gametogenesis in plants and animals,...