Microbiology Lecture Review: Chapters 4, 5, and 6

Comprehensive vocabulary flashcards covering the principles of microscopy, staining techniques, cell structures (prokaryotic and eukaryotic), and essential concepts of metabolism based on the provided microbiology lecture notes.

Genus

The first part of a scientific name that is always capitalized and underlined when hand-written or italicized when typed.

Species

The second part of a scientific name that is never capitalized but must be underlined when hand-written or italicized when typed.

Antonie van Leeuwenhoek

The first individual to observe microorganisms, using simple microscopes capable of magnifying objects between $100\times$ and $300\times$.

Microscopy

The technology employed to make very small objects visible to the human eye.

Wavelength

The distance between two adjacent crests or troughs of a light ray, represented by the Greek letter \text{Lambda}\text{ (}\boldsymbol{\text{\lambda}}\text{)}.

Resolution

The ability to perceive two separate items as discrete units rather than a single, overlapping image.

Reflection

Occurs when light strikes an object and bounces back, providing the object with its perceived color.

Transmission

The passage of light directly through an object, a process essential for viewing specimens through a microscope.

Absorption

The process where light rays are neither passed through nor bounced off an object but are instead taken up by it, often converting the energy into heat.

Luminescence

A phenomenon where absorbed light rays, particularly ultraviolet, are reemitted as longer wavelengths.

Refraction

The bending of light as it passes between media of different densities, characterized by an angle or degree of bending.

Index of Refraction

A measurement of the speed at which light passes through a specific material.

Immersion Oil

A substance with the same index of refraction as glass, used to prevent the bending of light and subsequent blurring of images at high magnifications.

Compound Light Microscope

A microscope that utilizes more than one lens to magnify specimens using visible light.

Condenser

A microscope component that converges light beams so they pass directly through the specimen.

Iris Diaphragm

A mechanism that controls the amount of light passing through the specimen into the objective lens.

Total Magnification

Calculated by multiplying the magnifying power of the objective lens by the magnifying power of the ocular lens (eyepiece).

Dark-Field Microscopy

A technique using a specialized condenser that reflects light off a specimen at an angle, resulting in a bright object against a dark background; ideal for light-sensitive organisms like spirochetes.

Phase-Contrast Microscopy

A method used to observe living, unstained organisms by detecting changes in light speed as it passes through objects of different refractive indices.

Fluorescent Microscopy

Uses ultraviolet light to excite molecules so they release light of longer wavelengths, often used in diagnostic procedures to detect specific antigens.

Scanning Electron Microscopy (SEM)

A type of microscopy that uses an electron beam to provide three-dimensional views of the exterior of cells at magnifications up to $50,000\times$.

Heat Fixation

A technique of passing a dried smear through a flame to kill organisms, attach them to the slide, and prime them to accept stains.

Cationic (Basic) Dyes

Positively charged stains, such as methylene blue or crystal violet, which are attracted to the negatively charged surfaces of bacterial cells.

Differential Stain

A staining technique using two or more dyes to distinguish between different kinds of organisms or different parts of an organism, such as the Gram stain.

Mordant

A chemical substance, such as iodine, that helps retain a stain within certain cells.

Gram-Positive

Bacteria that retain the primary crystal violet stain due to a thick layer of peptidoglycan in their cell walls, appearing purple.

Gram-Negative

Bacteria that do not retain crystal violet after decolorization and are instead colored red or pink by a safranin counterstain.

Acid-Fast Stain

A diagnostic stain used to detect organisms of the genus $\text{Mycobacterium}$, which retain red carbolfuchsin due to lipids in their cell walls.

Endospore

A highly resistant, non-reproductive resting stage produced by certain bacteria to survive extreme environmental conditions.

Prokaryote

Single-celled organisms, specifically bacteria and archaea, that lack a membrane-bound nucleus and organelles.

Eukaryote

Organisms whose cells contain a true nucleus and membrane-enclosed organelles, including plants, animals, fungi, and protists.

Binary Fission

The process by which prokaryotic cells divide, involving the duplication of chromosomes and the pinching of the cell membrane in half.

Peptidoglycan

The primary component of bacterial cell walls, forming a supporting net around the cell; Gram-positive cells may have up to $40$ layers.

Lipopolysaccharide (LPS)

An endotoxin found in the outer membrane of Gram-negative bacteria that is released when the cell dies, potentially causing fever and low blood pressure.

Periplasmic Space

A gap between the cell membrane and cell wall, most prominent in Gram-negative bacteria, serving as an active site for metabolism and enzyme activity.

Lysozyme

An enzyme found in tears that digests peptidoglycan, acting as a primary defense against eye infections.

Chemotaxis

The nonrandom movement of bacteria toward or away from chemical substances in their environment.

Conjugation Pili (F Pili)

Tiny, hollow projections that attach two bacterial cells and provide a pathway for the transfer of genetic material (DNA).

Svedberg (S) Units

The measurement unit for sedimentation rates used to determine the relative size of ribosomes; bacterial ribosomes are rated at $70S$ while eukaryotic ribosomes are $80S$.

Mitochondria

The organelles known as the powerhouse of eukaryotic cells, responsible for capturing energy in the form of $\text{ATP}$ through oxidative reactions.

Phagocytosis

A type of endocytosis where a cell engulfs microorganisms or debris into a large vacuole called a phagosome.

Metabolism

The sum of all chemical processes carried out by a living organism, divided into anabolism and catabolism.

Anabolism

Reactions that require energy to synthesize complex molecules from simpler ones for growth and repair.

Catabolism

Reactions that release energy by breaking down complex molecules into simpler ones.

Enzymes

Specialized proteins that act as catalysts, speeding up chemical reactions by lowering the required activation energy.

Active Site

The specific region on an enzyme's surface where it forms a loose association with its substrate.

Cofactor

An inorganic ion, such as magnesium or zinc, that improves the fit between an enzyme and its substrate.

Glycolysis

A ten-step metabolic pathway used by both aerobes and anaerobes to begin the breakdown of glucose into pyruvic acid, occurring in the cytoplasm.