Microscope, Cell Biology, Osmosis, and Enzyme Review

Vocabulary flashcards covering microscope anatomy, cell biology, plasma membrane transport and osmosis, and enzyme structure, function, and denaturation.

Magnification

The measure of how many diameters an object is enlarged under a microscope, calculated by multiplying ocular magnification (typically $10\times$) by objective magnification (for example, $10\times \times 40\times = 400\times$ total magnification).

Cell Theory

A foundational biological principle stating that the cell is the basic living unit of organization, all organisms are composed of one or more cells, all cells arise from preexisting cells, and cells contain hereditary information (DNA).

Prokaryote

Single-celled organisms in Domains Archaea and Bacteria (meaning 'before nucleus') that evolved before eukaryotes, lack most membrane-bound organelles, contain DNA in a concentrated nucleoid, and tend to grow rapidly and divide often.

Eukaryote

Organisms belonging to Domain Eukarya (including protists, fungi, plants, and animals; meaning 'true nucleus') characterized by specialized membrane-bound organelles, DNA contained inside a membrane-bound nucleus, and a size approximately $10\times$ larger than prokaryotes.

Nucleoid

The concentrated region of DNA within a prokaryotic cell that is not surrounded by a nuclear membrane.

Plasma Membrane

A selectively permeable membrane (also known as the cell membrane) that surrounds the cytoplasm of both prokaryotic and eukaryotic cells, regulating substance movement, receiving/transmitting information, and communicating with adjacent cells.

Cell Wall

A rigid layer located outside the plasma membrane in plant cells and prokaryotes that provides protection and structural shape.

Capsule

A jelly-like outer coating present on some prokaryotic cells used for protection and adhesion.

Pilus

A hair-like surface structure on prokaryotic cells used for attachment.

Flagellum

A long, whip-like appendage on cells used for locomotion.

Chloroplasts

Chlorophyll-containing organelles found in plant cells (such as Elodea) that serve as the site of photosynthesis.

Cytoplasm

The fluid-like substance (also called cytosol) surrounding organelles inside the cell.

Osmosis

The net movement of water molecules by diffusion across a selectively permeable membrane down its concentration gradient.

Selectively Permeable Barrier

A functional feature of plasma membranes that allows only specific molecules to cross into or out of the cell.

Phospholipid Bilayer

The double-layer lipid structure of plasma membranes consisting of hydrophilic ('water-loving') heads and hydrophobic ('water-repelling') tails that acts as a barrier to polar substances.

Aquaporins

Transport proteins embedded in plasma membranes that serve as specialized channels for the rapid facilitated diffusion of water molecules.

Tonicity

The relative concentration of solutes on either side of a plasma membrane, which determines the movement of water into or out of a cell.

Isotonic Solution

A solution environment where solute concentrations are equal inside and outside the cell, resulting in no net movement of water and no change in cell size or shape.

Hypotonic Solution

A solution with a lower solute concentration (higher water concentration) than the inside of a cell, causing water to flow into the cell.

Hypertonic Solution

A solution with a higher solute concentration (lower water concentration) than the inside of a cell, causing water to move out of the cell.

Hypothesis

A testable statement in the scientific method used to predict experimental outcomes based on existing information, which is not an educated guess and does not require an if/then format.

Enzyme

A protein that acts as a biological catalyst, speeding up chemical reactions by lowering activation energy without being consumed or permanently altered in the process.

Activation Energy

The threshold amount of energy required for a chemical reaction to occur, which is lowered by enzymes.

Substrate

The specific reactant molecule that binds to an enzyme's active site and is changed or broken down during a reaction.

Product

The resulting substance(s) formed at the end of an enzyme-catalyzed chemical reaction.

Active Site

The specific region on an enzyme where the substrate binds according to the Lock and Key Theory.

Denaturation

The structural modification of a protein or enzyme's shape caused by extreme environmental conditions (such as high heat or extreme pH), rendering it unable to fit its substrate.

Peroxidase

An enzyme found in potatoes that breaks down hydrogen peroxide ($\text{H}_2\text{O}_2$) into water ($\text{H}_2\text{O}$) and oxygen gas ($\text{O}_2$).

Compound Microscope Anatomy

The physical parts of a standard light microscope, including eyepieces, diopter rings, objectives, stage, specimen holder, condenser, focus knobs (coarse/fine), stage motion knobs (X/Y axis), brightness control dial, power switch, and arm.

Bacterial Cell Anatomy

The structural layout of a typical bacterial cell model, illustrating features such as the nucleoid, plasma membrane, cell wall, capsule, pilus, flagellum, outer membrane, and ribosomes.

Eukaryotic Cell Diagrams

Diagrammatic comparison showing the shared organelles of animal and plant cells (such as the nucleus, cytoplasm, plasma membrane, and mitochondria) alongside plant-exclusive organelles (cell wall and chloroplasts).