Cell: The Building Block of Life

Comprehensive vocabulary flashcards covering the biological concepts of cell structure, function, organelles, transport mechanisms, and division as presented in the lecture notes.

Thermophiles

Heat-loving bacteria that are unicellular and found in extreme environments like the hot springs of Puga Valley.

Cell

The basic structural and functional unit of all living organisms.

Tissue

A group of similar cells performing similar functions.

Limit of Resolution

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

Micrometre ($\mu m$)

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

Resolution

A measure of clarity in a microscope representing the ability to distinguish between two close objects.

Cell Membrane

A thin, selectively permeable membrane made of lipids and proteins that surrounds a cell and protects its contents; also called the plasma membrane.

Osmosis

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

Diffusion

The net movement of particles from a higher concentration to a lower concentration, which occurs 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 inside the cell, causing the cell to swell.

Hypertonic Solution

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

Fluid-Mosaic Model

A model of the cell membrane describing a lipid bilayer where molecules can move sideways and rotate, with proteins acting like gatekeepers.

Cell Wall

An additional rigid layer outside the cell membrane in plants, fungi, and bacteria that provides structural support and protection.

Cellulose

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

Cytoplasm

A semi-fluid, jelly-like substance that fills the cell and contains various organelles.

Prokaryotic Cells

Cells that lack a well-defined nucleus and membrane-bound organelles; their genetic material is found in a region called the nucleoid.

Eukaryotic Cells

Cells that have a well-defined nucleus enclosed by a membrane and several membrane-bound organelles.

Viruses

Acellular infectious agents composed of genetic material with a protein coat, too small to be seen under a light microscope.

Nucleus

The double-layered organelle often called the "house of coded instructions" that contains the cell's genetic material.

Chromosomes

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

Genes

The functional segments of DNA that contain genetic information.

Ribosomes

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

Rough Endoplasmic Reticulum (RER)

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

Smooth Endoplasmic Reticulum (SER)

A type of ER without ribosomes involved 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.

Lysosomes

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

Mitochondria

Known as the "powerhouse of the cell," these produce energy as $ATP$ through cellular respiration and contain their own DNA and ribosomes.

Adenosine Triphosphate (ATP)

The molecule that acts as the energy currency for most cellular activities.

Plastids

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

Chloroplasts

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

Chromoplasts

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

Leucoplasts

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

Vacuoles

Organelles used for storage of water, minerals, and waste; plant cells typically have one large central vacuole filled with cell sap.

Cell Division

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

Mitosis

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

Meiosis

A two-step cell division process that produces four gametes with half the original chromosome number, creating genetic diversity.

Totipotency

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

Contact Inhibition

A process in animal cells where cell division stops when cells come in 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 quality control.

Cell Theory

The principle formulated by Schleiden, Schwann, and Virchow stating that all living organisms are made of cells, they are the basic unit of life, and all cells arise from pre-existing cells.