Cell: The Building Block of Life

A comprehensive set of vocabulary flashcards covering cell biology, including microscopy, cell structures, organelles, transport mechanisms, cell division, and historical scientific contributions.

Thermophiles

Heat-loving unicellular bacteria that live in extreme environments like the hot springs of Puga Valley in Ladakh.

Limit of resolution

The ability of the human eye to see two very close objects as separate and distinct, which is $0.1\,mm$ when viewed from about $25\,cm$.

Robert Hooke

The first person to observe a cell in 1665 using a self-designed microscope to examine a thin slice of cork.

Total magnification

The magnifying power of a microscope calculated by multiplying the power of the eyepiece by the power of the objective lens.

Electron microscope

A powerful instrument that uses a beam of electrons instead of light to reveal cell structures at the nanometre scale.

Cell membrane

A thin, selectively permeable boundary made of lipids and proteins that protects the cell's contents; also called the plasma membrane.

Osmosis

The diffusion of water across a selectively permeable membrane from an area with more water and less solute to an area with less water and more solute.

Diffusion

The net movement of particles from a higher to a lower concentration which occurs due to a concentration gradient.

Isotonic solution

A solution where the solute concentration of the extracellular medium is equal to the solute concentration of the intracellular medium.

Hypotonic solution

A solution where the solute concentration of the extracellular medium is less than the solute concentration of the intracellular medium.

Hypertonic solution

A solution where the solute concentration of the extracellular medium is greater than the solute concentration of the intracellular medium.

Fluid-mosaic model

A model describing the cell membrane as a lipid bilayer with proteins embedded in it, where molecules can move sideways, flip, and rotate.

Cell wall

An additional rigid, permeable layer outside the cell membrane in plants, fungi, and bacteria; in plants, it is primarily made of cellulose.

Prokaryotic cells

Cells that lack a well-defined nucleus and membrane-bound organelles, such as bacterial cells.

Eukaryotic cells

Cells that have a well-defined nucleus and several membrane-bound organelles, such as plant and animal cells.

Cytoskeleton

A network of fine fibres in eukaryotic cells that provides structural support, maintains cell shape, and enables movement.

Cell inclusions

Substances stored in the cytoplasm, such as starch in plant cells or crystals of calcium oxalate or silica.

Nucleolus

A dense round body in the nucleus where the synthesis of ribosomal subunits takes place.

Chromosomes

Rod-shaped structures visible during cell division composed of DNA and proteins that carry genetic information.

Genes

The functional segments of DNA molecules that contain instructions for the inheritance of characters.

Chromatin

An entangled mass of thread-like structures visible in a non-dividing cell that organizes into chromosomes when the cell prepares to divide.

Nucleoid

The region in a prokaryotic cell containing a single circular DNA molecule associated with specific proteins.

Ribosomes

Tiny structures, either free in the cytoplasm or attached to the ER, that serve as the sites of protein synthesis.

Rough Endoplasmic Reticulum (RER)

A network of membranes with ribosomes attached to its surface, mainly involved in protein synthesis and secretion.

Smooth Endoplasmic Reticulum (SER)

A network of membranes without ribosomes involved in the synthesis and storage of fats and hormones.

Golgi apparatus

Stacks of flattened, sac-like structures that modify, sort, and package proteins and lipids into vesicles.

Lysosomes

Single membrane-bound sacs filled with enzymes that break down unwanted proteins, fats, and cellular waste.

Mitochondria

The 'powerhouses of the cell' where glucose is broken down to release energy stored as Adenosine Triphosphate (ATP).

Cristae

Finger-like projections of the inner mitochondrial membrane that increase the surface area for chemical reactions.

Chloroplasts

Double-membrane-bound plastids containing the green pigment chlorophyll used for photosynthesis.

Stroma

The semi-fluid substance inside a chloroplast where sugars are synthesized and starch granules are stored.

Chromoplasts

Plastids containing yellow, orange, or red pigments that provide color to flowers and fruits to attract pollinators and dispersers.

Leucoplasts

Colorless plastids that store food materials such as starch, oils, or proteins.

Vacuoles

Organelles used for storage of water, minerals, and waste; in mature plant cells, they contain cell sap and maintain cell firmness.

Cell cycle

The controlled and orderly process by which eukaryotic cells divide.

Mitosis

A type of cell division that produces two genetically identical daughter cells from one parent cell, used for growth and repair.

Meiosis

A two-step cell division process that produces four gametes with half the chromosome number of the parent cell.

Cell culture

The process of growing plant or animal cells outside the body in a nutrient-rich medium under sterile conditions.

Cell Theory

The principle formulated by Schleiden, Schwann, and Virchow stating all organisms are made of cells, and all cells arise from pre-existing cells.

Contact inhibition

A process in animal cells where cell division stops when cells come into contact with neighboring cells.

Programmed Cell Death (PCD)

A genetically regulated process of selective cell destruction essential for normal development and immune function.

Totipotency

The ability of any living plant cell to develop into a complete plant if provided with suitable nutrients and conditions.