Cell: The Building Block of Life Flashcards

Comprehensive vocabulary flashcards covering the structural components, functions, and discovery of cells as described in Chapter 2.

Thermophiles

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

Limit of resolution of the human eye

The ability 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 while examining a thin slice of cork.

Resolution

A measure of the clarity of an image when using a microscope.

Contrast

The difference in brightness between various parts of an object viewed under a microscope.

Electron microscope

Powerful instruments that use a beam of electrons instead of light to produce highly magnified images at the nanometre scale.

Cell membrane (Plasma membrane)

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

Osmosis

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

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 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

The structural model of the cell membrane consisting of a lipid bilayer with attached proteins that can move sideways, flip, and rotate.

Cell wall

A rigid, permeable additional covering outside the cell membrane in plants, fungi, and bacteria, primarily made of cellulose in plants.

Cytoplasm

A semi-fluid, jelly-like substance inside the cell that contains several sub-cellular components called organelles.

Prokaryotic cells

Cells that lack a well-defined nucleus and membrane-bound organelles, typically found in bacteria.

Eukaryotic cells

Cells, such as those in plants and animals, that have a well-defined nucleus and several membrane-bound organelles.

Cytoskeleton

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

Cell inclusions

Stored materials in the cytoplasm such as starch, crystals of calcium oxalate, or silica.

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, which carry genetic information for inheritance.

Genes

The functional segments of DNA molecules that contain genetic information.

Nucleoid

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

Ribosomes

Tiny structures that are the sites of protein synthesis, found either freely in the cytoplasm or attached to the endoplasmic reticulum.

Rough Endoplasmic Reticulum (RER)

ER with ribosomes attached to its surface, primarily involved in protein synthesis and secretion.

Smooth Endoplasmic Reticulum (SER)

ER without ribosomes used in the synthesis and storage of fats (lipids) and hormones.

Golgi apparatus

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

Lysosomes

Single membrane-bound sacs filled with enzymes used to break down unwanted materials and damaged parts of the cell.

Mitochondria

The 'powerhouses of the cell' where cellular respiration occurs to release energy stored as Adenosine Triphosphate (ATP).

Chloroplasts

Double-membrane-bound plastids containing the green pigment chlorophyll, where photosynthesis takes place in plant cells.

Chromoplasts

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

Leucoplasts

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

Cell division

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

Mitosis

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

Meiosis

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

Cell theory

A 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 the cells come in contact with neighbouring cells.

Programmed Cell Death (PCD)

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

Totipotency

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