Comprehensive Notes on Cell Theory Key Contributions to Cell Theory Matthias Schleiden (1838): German botanist. Studied plants and observed that all plants are composed of different types of cells forming tissues. Theodore Schwann (1839): British zoologist. Studied animal cells and […]

Cell Envelope Definition: A chemically complex, three-layered structure found in most prokaryotic cells, particularly bacterial cells. Layers: Glycocalyx (outermost). Cell Wall (middle). Plasma Membrane (innermost). Functions: Layers perform distinct functions but act together as a single protective unit. Gram Staining: […]

Ribosomes in Prokaryotes Location: Associated with the plasma membrane of prokaryotic cells. Size and Structure: Approximately 15 nm by 20 nm in size. Composed of two subunits: 50S (large subunit). 30S (small subunit). Together, these form 70S ribosomes (prokaryotic ribosomes). […]

Definition: The endomembrane system includes a group of membranous organelles that work together in a coordinated manner to perform specific cellular functions. Components of the Endomembrane System: Endoplasmic Reticulum (ER): Network of membranous tubules and sacs. Plays a role in […]

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 […]

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. […]

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 […]

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 […]

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 […]