Cell: The Building Block of Life Vocabulary Flashcards

Vocabulary flashcards covering key biological terms, cell structures, cell functions, and scientists from Chapter 2.

Thermophiles

Heat-loving unicellular bacteria that survive in extreme environments, such as the hot springs of Puga Valley in Ladakh where water temperatures near the boiling point.

Limit of Resolution of the Human Eye

The minimum distance between two points at which they can still be distinguished as separate and distinct by the naked eye, which is $0.1\,\text{mm}$ when viewed from about $25\,\text{cm}$.

Robert Hooke

The English scientist who first observed cells in $1665$ by examining thin slices of cork under a self-designed microscope with about $200\text{--}300\times$ magnification.

Osmosis

The net movement of water through a selectively permeable membrane from an area with higher water concentration (dilute solution) to an area with lower water concentration (concentrated solution).

Diffusion

The net movement of particles from a region of higher concentration to a region of lower concentration driven by a concentration gradient.

Isotonic Solution

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

Hypotonic Solution

A solution in which the solute concentration of the extracellular medium is less than the solute concentration of the intracellular medium, causing water to enter the cell.

Hypertonic Solution

A solution in which the solute concentration of the extracellular medium is greater than the solute concentration of the intracellular medium, causing water to leave the cell.

Fluid-Mosaic Model

A model describing the cell membrane structure as a fluid lipid bilayer with embedded proteins arranged like tiles in a mosaic.

Cell Wall

A rigid, permeable outer covering surrounding the cell membrane in plants, fungi, and bacteria that provides structural support and protection.

Cellulose

A complex carbohydrate composed of linked glucose units that forms the main structural component of plant cell walls.

Prokaryotic Cells

Primitive cells that lack a well-defined nucleus and membrane-bound organelles, carrying out cellular activities directly in the cytoplasm.

Eukaryotic Cells

Cells containing a well-defined nucleus enclosed by a nuclear membrane and distinct membrane-bound organelles.

Cytoskeleton

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

Nucleolus

A dense, round structure within the nucleus responsible for synthesizing ribosomal subunits.

Genes

Functional segments of DNA that store hereditary information for the transmission of traits from parents to offspring.

Chromatin

An entangled mass of thread-like structures composed of DNA and proteins found in the nucleus of a non-dividing cell.

Nucleoid

The poorly defined region in a prokaryotic cell that contains its single circular DNA molecule without a surrounding membrane.

Ribosomes

Tiny non-membrane-bound structures present in the cytoplasm or on the endoplasmic reticulum that serve as the sites of protein synthesis.

Rough Endoplasmic Reticulum (RER)

A network of membranes studded with ribosomes on its surface, primarily involved in protein synthesis and secretion.

Smooth Endoplasmic Reticulum (SER)

A region of endoplasmic reticulum lacking ribosomes on its surface, responsible for synthesizing and storing lipids and hormones.

Golgi Apparatus

An organelle consisting of stacks of flattened, sac-like structures that modifies, sorts, and packages proteins and lipids into vesicles.

Camillo Golgi

The Italian scientist who first observed the Golgi apparatus in $1898$ within the nerve cells of a barn owl using special staining techniques.

Lysosomes

Single membrane-bound sacs containing digestive enzymes that break down waste materials, foreign substances, and worn-out organelles.

Mitochondria

Double-membrane-bound organelles known as the 'powerhouses of the cell' where cellular respiration generates ATP.

Cristae

Finger-like inner membrane folds of a mitochondrion that increase surface area for energy-producing chemical reactions.

Chloroplasts

Double-membrane-bound plastids containing green chlorophyll pigment and stroma where photosynthesis occurs.

Chromoplasts

Plastids containing non-green pigments (yellow, orange, or red) that give bright colors to flowers and fruits to attract pollinators and seed dispersers.

Leucoplasts

Colourless plastids that serve as storage sites for food materials like starch, oils, or proteins.

Vacuole

A fluid-filled, single membrane-bound storage organelle containing cell sap that stores nutrients and waste while providing turgidity to plant cells.

Mitosis

A process of cell division producing two genetically identical daughter cells containing the exact same number of chromosomes as the parent cell.

Meiosis

A two-step cell division process occurring in reproductive organs that produces four gametes, each with half the chromosome number of the parent cell.

Contact Inhibition

A mechanism in normal animal cells where cell division halts upon making physical contact with neighboring cells.

Programmed Cell Death (PCD)

A genetically regulated and organized process of selective cell destruction essential for normal organismal development and cellular quality control.

Totipotency

The inherent ability of a living plant cell to develop into a complete plant when provided with appropriate nutrients and environmental conditions.