General Observations Plant Cell (Onion Peel): Outer boundary: Distinct cell wall and an inner cell membrane. Contains a dense, membrane-bound structure called the nucleus. Animal Cell (Human Cheek Cell): Outer boundary: Only the cell membrane. Contains a dense, membrane-bound nucleus. Key Components of a Cell Nucleus: Dense, membrane-bound structure...
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...
General Characteristics Represented by: Bacteria, blue-green algae, mycoplasma, and PPLO (Pleuro Pneumonia Like Organisms). Size and Growth: Generally smaller than eukaryotic cells. Multiply more rapidly. Shape: Four basic shapes of bacteria: Bacillus: Rod-like. Coccus: Spherical. Vibrio: Comma-shaped. Spirillum: Spiral. Structure and Organization Cell Wall: Surrounds the cell membrane. Absent...
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,...
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: Based on cell envelope differences, bacteria are classified into:...
Prophase I: Longer and more complex than prophase of mitosis. Subdivided into five phases based on chromosomal behavior: Leptotene, Zygotene, Pachytene, Diplotene, and Diakinesis. 1. Leptotene: Chromosomes gradually become visible under a light microscope. Compaction of chromosomes continues throughout this stage. 2. Zygotene: Chromosomes start pairing together, a process...
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). Function: Sites of protein synthesis. Polysome (Polyribosomes): Multiple ribosomes...
General Characteristics of Eukaryotic Cells: Organisms Included: Protists, plants, animals, and fungi are all eukaryotes. Cytoplasm Compartmentalization: Eukaryotic cells have extensive compartmentalization of cytoplasm due to the presence of membrane-bound organelles. Nucleus: Eukaryotic cells possess a well-organized nucleus enclosed by a nuclear envelope. Cytoskeletal and Locomotory Structures: Eukaryotic cells...
1. Structure of the Cell Membrane: Discovery and Studies: The detailed structure of the cell membrane was studied using the electron microscope in the 1950s. Chemical studies, particularly on human red blood cells (RBCs), showed that the membrane is mainly composed of lipids and proteins. Lipid Composition: Major lipids...
Definition: The cell wall is a non-living rigid structure forming the outer covering of the plasma membrane in fungi and plants. Functions: Provides shape to the cell. Protects the cell from mechanical damage and infections. Facilitates cell-to-cell interaction. Acts as a barrier to undesirable macromolecules. Composition: Algae: Cell wall...