Microbiology - test 1

What is the path of light in a light microscope?

Light passes from the light source to the condenser, focuses on the specimen, passes through to the objective lens, and then to the ocular lens.

What is passive transport?

Movement of substances down the concentration gradient (high to low) without using energy.

What is active transport?

Movement of substances against the concentration gradient (low to high) requiring energy, usually ATP.

What is glycocalyx?

A sticky, sugar-rich outer covering found on some bacteria that protects the cell and helps in adhesion.

What is dehydration synthesis?

A chemical reaction that joins two molecules by removing water.

What is the purpose of spore staining?

To differentiate between spore-forming and non-spore-forming bacteria.

What are the properties of water that make it essential for life?

Polarity, cohesion and adhesion, high specific heat, and solvent properties.

What is the structure of the plasma membrane?

Composed of a phospholipid bilayer with embedded proteins, where hydrophilic heads face outward and hydrophobic tails face inward.

How do light microscopes differ from electron microscopes?

Light microscopes use visible light with a magnification up to 1000x, while electron microscopes use electron beams with magnification up to 1,000,000x.

What is an amine group?

A functional group (-NH2) found in amino acids that is basic in nature.

What is the role of phospholipids?

Key components of cell membranes containing a hydrophilic phosphate group and two hydrophobic fatty acid tails.

What is the function of the capsule in bacteria?

Prevents phagocytosis and aids in biofilm formation.

What happens in facilitated diffusion?

Passive transport mechanism that uses channel or carrier proteins to move substances across the membrane.

What occurs during endocytosis?

A process where large particles are transported into the cell.

What is the primary stain used in spore staining?

Malachite green.

What is the definition of osmosis?

The diffusion of water across a selectively permeable membrane.

What is a key characteristic of the capsule structure?

It is a thick, gelatinous layer outside of the cell wall.

Why is high specific heat important for water?

It allows water to absorb a lot of heat before changing temperature, stabilizing temperatures.

Prokaryote

A type of cell that has no membrane-bound nucleus, typically with one circular chromosome.

Eukaryote

A type of cell that contains a membrane-bound nucleus and paired chromosomes.

Binary fission

The method of asexual reproduction in prokaryotes in which a cell divides into two genetically identical cells.

Capsule

A closed structure that is organized and firmly attached to the cell wall, often contributing to virulence by preventing phagocytosis.

Flagella

Long, filamentous appendages that propel bacteria, composed of protein flagellin.

Fimbriae

Hairlike appendages that allow for attachment to surfaces.

Gram-positive bacteria

Bacteria characterized by a thick peptidoglycan layer in their cell wall.

Gram-negative bacteria

Bacteria characterized by a thin peptidoglycan layer and an outer membrane.

Teichoic acid

Molecules found in gram-positive bacterial cell walls, providing structural support and regulating cation movement.

Peptidoglycan

A polymer that forms the structural component of the bacterial cell wall.

Osmosis

The movement of water across a selectively permeable membrane from an area of high water concentration to an area of lower water concentration.

Endosome

A membrane-bound compartment inside eukaryotic cells that contains endocytosed materials.

Nucleoid

A region within prokaryotic cells where the circular DNA (chromosome) is located.

Mitochondria

Organelles that are the sites of ATP production through cellular respiration.

Chloroplasts

Organelles found in plant cells that are involved in photosynthesis.

Cilia

Short projections used for locomotion or moving substances along the cell surface, numerous in number.

Endospores

Resistant structures produced by some bacteria during nutrient depletion, capable of withstanding harsh conditions.

Mycoplasmas

Bacteria that lack cell walls, often having sterols in their plasma membrane.

Archaea

Microorganisms similar to bacteria but with distinct biochemistry and genetics, sometimes having pseudomurein cell walls.

What is the smallest unit of matter that cannot be subdivided into smaller substances?

Atom

What are the three primary components of an atom?

Electrons, protons, and neutrons.

What is the atomic number of an element?

The number of protons in the nucleus of an atom.

What is the difference between atomic mass and atomic number?

Atomic mass is the total number of protons and neutrons, while atomic number is just the number of protons.

What are isotopes?

Atoms of the same element that have different numbers of neutrons.

What type of bond involves the sharing of electron pairs between atoms?

Covalent bond

What is a cation?

An atom that loses electrons and becomes positively charged.

What defines a hydrogen bond?

A bond formed when a hydrogen atom covalently bonded to an oxygen or nitrogen atom is attracted to another oxygen or nitrogen atom.

Define a covalent bond.

A bond formed when two atoms share one or more pairs of electrons.

What does it mean for a compound to be organic?

It contains carbon and typically also hydrogen.

What is the pH scale used to measure?

The acidity or alkalinity of a solution.

What substance can act as both an acid and a base?

Amphoteric substance.

What are carbohydrates primarily used for in living organisms?

They serve as cell structures and energy sources.

What is dehydration synthesis?

A reaction in which two molecules are joined by the removal of water.

What is the primary structure of proteins?

The sequence of amino acids in a polypeptide chain.

What are the building blocks of nucleic acids?

Nucleotides.

Define ATP.

Adenosine triphosphate, a molecule that stores and releases chemical energy for cellular reactions.

How do simple lipids differ from complex lipids?

Simple lipids consist of glycerol and fatty acids, while complex lipids may also contain phosphates and other elements.

What is the role of enzymes in cellular processes?

They act as catalysts to speed up chemical reactions.

What characterizes an exergonic reaction?

It releases energy.

What does the term 'anabolism' refer to?

The synthesis of molecules in a cell.

How does the tertiary structure of proteins form?

It occurs when the secondary structures fold irregularly, forming a complex three-dimensional shape.

What are macromolecules?

Large molecules formed by the combination of smaller subunits called monomers.

Microscopy

The use of microscopes to observe small objects that are not visible to the naked eye.

Total Magnification

The overall magnification of an image, calculated by multiplying the magnification of the objective lens by the magnification of the ocular lens.

Resolution

The ability of a microscope to distinguish between two points that are close together.

Refractive Index

A measure of the bending ability of light as it passes through a medium.

Brightfield Illumination

A microscopy technique where dark objects are visible against a bright background.

Darkfield Microscopy

A technique that makes light objects visible against a dark background, using a special condenser.

Phase-Contrast Microscopy

Allows examination of living specimens by bringing together direct and diffracted light rays.

Differential Interference Contrast (DIC) Microscopy

Uses two light beams and prisms to enhance the contrast and color of the specimen.

Fluorescence Microscopy

A method that uses UV light and fluorescent substances to illuminate specimens.

Confocal Microscopy

Uses a laser to illuminate a single plane of a specimen and construct a three-dimensional image.

Two-Photon Microscopy

A technique that uses long-wavelength light to excite fluorescent dyes in thick specimens.

Electron Microscopy

Uses electrons instead of light to visualize small objects, offering greater resolution.

Transmission Electron Microscopy (TEM)

A type of electron microscopy that passes electrons through ultra-thin sections of a specimen.

Scanning Electron Microscopy (SEM)

Provides three-dimensional images by scanning the surface of a specimen with a beam of electrons.

Scanning Tunneling Microscopy

Uses a tungsten probe to reveal details of a specimen's surface at near-atomic resolution.

Atomic Force Microscopy (AFM)

Uses a metal-and-diamond probe to produce detailed three-dimensional images of a specimen.

Simple Stains

Use of a single basic dye to enhance visualization of the entire microorganism.

Gram Stain

A differential stain that classifies bacteria into gram-positive and gram-negative based on cell wall structure.

Acid-Fast Stain

Identifies mycobacteria based on their waxy cell wall that resists decolorization.

Negative Staining

A staining technique that colors the background rather than the cells, highlighting capsules.

Endospore Staining

A method to visualize internal, dormant structures in bacteria that are resistant to staining.

Flagella Staining

A technique to thicken and visualize flagella, the structures that enable bacterial locomotion.