Cell: The Building Block of Life

A Comprehensive vocabulary list covering cell biology, microscopy, organelle function, and cell division based on the lecture material.

Thermophiles

Heat-loving, unicellular bacteria that live in environments like hot springs with temperatures near the boiling point of water.

Birbal Sahni Institute of Palaeosciences

The institute in Lucknow whose scientists studied hot springs in Puga Valley and found rapid calcium carbonate formation.

Cell

The basic level and fundamental unit of structure and function at which life exists in all living organisms.

Tissues

A group of similar cells performing similar functions.

Organ system

Several organs working together to perform a complete function, such as the respiratory system.

Limit of resolution of the human eye

The ability of the eye to see two very close objects as separate, which is approximately $0.1\,mm$ at a distance of $25\,cm$.

Robert Hooke

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

Light microscope

A tool used in laboratories to observe objects under visible light using objective lenses and an eyepiece.

Electron microscope

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

Nanometre

A unit of measurement equal to one-billionth of a metre.

Micrometre ($\mu m$)

A unit of measurement where $1\,mm = 1000\,\mu m$.

Magnification

The process of making an object appear larger; total magnification is calculated by multiplying the power of the eyepiece by the power of the objective lens.

Cell membrane

A thin, selectively permeable boundary made of lipids and proteins that protects the cell and defines its individuality.

Fluid-mosaic model

A model describing the cell membrane as a lipid bilayer where molecules can move sideways, flip, and rotate like tiles in a mosaic.

Selective permeability

A property of the cell membrane that allows some substances to pass through while blocking others.

Osmosis

The diffusion of water across a selectively permeable membrane from an area of higher water concentration to lower water concentration.

Diffusion

The net movement of particles from a higher concentration to a lower concentration occurring even without a membrane.

Isotonic solution

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

Hypotonic solution

A solution where the solute concentration of the extracellular medium is lower than the concentration inside the cell, causing the cell to swell.

Hypertonic solution

A solution where the solute concentration of the extracellular medium is higher than the concentration inside the cell, causing the cell to shrink.

Lipid bilayer

Two layers of special fat molecules with water-attracting heads facing outwards and water-repelling tails facing inwards.

Cell wall

An additional rigid, permeable layer outside the cell membrane found in plants, fungi, and bacteria for protection and support.

Cellulose

A type of carbohydrate formed by linked glucose units that primarily makes up the plant cell wall.

Cytoplasm

A semi-fluid, jelly-like substance inside the cell containing organelles and other substances.

Organelles

Sub-cellular components within the cytoplasm that perform specific jobs, such as building materials or providing energy.

Prokaryotic cells

Primitive cells, like bacteria, that lack a well-defined nucleus and membrane-bound organelles.

Eukaryotic cells

Complex cells, like plant and animal cells, that have a well-defined nucleus and membrane-bound organelles.

Nucleoid

The region in a prokaryotic cell that contains the genetic material as a single circular molecule.

Cytoskeleton

A network of fine fibres in eukaryotic cells that provides structural support and enables internal transport and movement.

Cell inclusions

Stored substances in the cytoplasm, such as starch, calcium oxalate, or silica.

Nuclear membrane

A double-layered covering of the nucleus containing pores for the transfer of material to the cytoplasm.

Nucleolus

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

Chromosomes

Rod-shaped structures composed of DNA and proteins that contain information for inheritance.

DNA (Deoxyribonucleic acid)

Molecules that contain the genetic information of an organism.

Genes

The functional segments of DNA molecules.

Chromatin

An entangled mass of thread-like structures in a non-dividing cell that organizes into chromosomes during cell division.

Ribosomes

Tiny structures, either free in cytoplasm or attached to ER, which serve as protein factories.

Rough Endoplasmic Reticulum (RER)

An organelle with ribosomes attached to its surface involved in protein synthesis and secretion.

Smooth Endoplasmic Reticulum (SER)

An organelle 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 waste and damaged cell parts.

Mitochondria

The powerhouses of the cell where glucose is broken down to release energy during cellular respiration.

Adenosine Triphosphate (ATP)

The energy currency of the cell stored in mitochondria and used for cellular activities.

Plastids

Organelles in plant cells used for food synthesis and storage, including chloroplasts, chromoplasts, and leucoplasts.

Chloroplasts

Double-membrane-bound organelles containing chlorophyll where photosynthesis occurs.

Chromoplasts

Pigmented plastids (yellow, orange, or red) that provide bright colors to flowers and fruits.

Leucoplasts

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

Vacuoles

Organelles for storage and support; plants have one large central vacuole filled with cell sap.

Cell division

The process by which new cells are formed from pre-existing cells for growth, repair, or reproduction.

Mitosis

A type of cell division that produces two genetically identical daughter cells for growth and repair.

Meiosis

A two-step cell division process occurring in reproductive organs that produces four daughter cells (gametes) with half the original chromosome number.

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 arise from pre-existing cells.

Contact inhibition

A process where animal cell division stops when cells come into contact with neighbors; this system fails in cancer cells.

Programmed Cell Death (PCD)

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

Totipotency

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