Cell: The Building Block of Life

A comprehensive set of vocabulary flashcards covering cell biology concepts, organelles, microscopy, and cell division based on the lecture notes.

Thermophiles

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

Limit of resolution of the human eye

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.

Micrometre ($\mu m$)

A unit of measurement used for cell size where 1\text{ millimetre (mm)} = 1000\text{ micrometre (\mu m)}.

Electron microscope

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

Cell membrane

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

Osmosis

The movement of water through a selectively permeable membrane from an area with more water (dilute solution) to an area with less water (concentrated solution).

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, causing cells to swell.

Hypertonic solution

A solution where the solute concentration of the extracellular medium is greater than the solute concentration of the intracellular medium, causing cells to shrink.

Fluid-mosaic model

A model describing the cell membrane as a fluid lipid bilayer with embedded proteins that act like gatekeepers.

Cell wall

A rigid but permeable additional 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, with genetic material located in a region called the nucleoid.

Eukaryotic cells

Cells that possess a well-defined nucleus and several membrane-bound organelles like mitochondria and the Golgi apparatus.

Cytoskeleton

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

Nucleolus

A dense round body within 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

Functional segments of DNA that contain information for the inheritance of characters.

Rough Endoplasmic Reticulum (RER)

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

Smooth Endoplasmic Reticulum (SER)

An organelle without ribosomes on its surface involved in the synthesis and storage of fats (lipids) and hormones.

Golgi apparatus

A stack of flattened sac-like structures that modifies, sorts, and packages proteins and lipids into vesicles for transport.

Lysosomes

Single membrane-bound sacs filled with enzymes that break down waste materials, unwanted proteins, and damaged cell parts.

Mitochondria

The 'powerhouses of the cell' that release energy through cellular respiration and store it in the form of Adenosine Triphosphate (ATP).

Cristae

Finger-like projections formed by the folding of the inner mitochondrial membrane to increase surface area for chemical reactions.

Chloroplasts

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

Chromoplasts

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

Leucoplasts

Colourless plastids used for storing food materials such as starch, oils, or proteins.

Mitosis

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

Meiosis

A two-step cell division process that produces four gametes with half the original chromosome number for sexual reproduction.

Cell culture

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

Cell Theory

The biological principle stating all organisms are made of cells, the cell is the basic unit of life, 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 neighbouring cells; this control is lost 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 mature plant cell to develop into a complete plant if provided with suitable nutrients and conditions, a concept proposed by Gottlieb Haberlandt.