Definition: Minute, membrane-bound vesicles found in both plant and animal cells. Contain various enzymes necessary for cellular processes. Characteristics: Enclosed by a single membrane. Small in size, making them microscopic and distinct. Functions: Facilitate specialized metabolic reactions due to their […]

Discovery: First described by Robert Brown in 1831. The material in the nucleus stained by basic dyes was named chromatin by Flemming. Structure of Nucleus Interphase Nucleus: Components: Chromatin: Highly extended nucleoprotein fibers. Nuclear Matrix: Gel-like substance within the nucleus. […]

Centrosome: An organelle usually containing two cylindrical structures called centrioles. Surrounded by amorphous pericentriolar material. Plays a key role in cell division by forming the spindle apparatus in animal cells. Centrioles: Two centrioles in a centrosome are positioned perpendicular to […]

Definition & Structure: Hair-like outgrowths of the cell membrane. Two types: Cilia: Small structures. Function like oars to move the cell or the surrounding fluid. Flagella: Longer structures. Primarily responsible for cell movement. Prokaryotic Flagella: Present in bacteria but structurally […]

Definition: A complex network of filamentous, proteinaceous structures present in the cytoplasm. Composed of microtubules, microfilaments, and intermediate filaments. Components: Microtubules: Hollow, tube-like structures made of tubulin proteins. Microfilaments: Thin, thread-like filaments primarily composed of actin proteins. Intermediate Filaments: Intermediate-sized […]

Discovery: Observed as dense particles under an electron microscope by George Palade in 1953. Granular structures composed of ribonucleic acid (RNA) and proteins. Not surrounded by any membrane. Classification: Eukaryotic Ribosomes: Size: 80S. Composed of two subunits: Larger subunit: 60S. […]

Definition & Occurrence: Plastids are present in all plant cells and euglenoids. Easily observable under a microscope due to their large size. Contain specific pigments that impart distinct colors to plants. Types of Plastids (Based on Pigments): Chloroplasts: Contain chlorophyll […]

Mitochondria: Definition Often called the “powerhouses” of the cell. Not easily visible under a microscope unless specifically stained. Number Varies depending on the cell’s physiological activity (more active cells have more mitochondria). Size and Shape Variable, but typically sausage-shaped or […]

Vacuoles: Definition Membrane-bound sacs within the cytoplasm of a cell. Membrane Surrounded by a single membrane called the tonoplast. Contents Water Sap Excretory products (waste) Other materials not useful to the cell Role in Plant Cells Can occupy up to […]