Microbiology Lecture Exam #1 Flashcards

Microbiology

The study of organisms too small to be seen without magnification, including bacteria, fungi, protozoa, algae, helminths, and viruses.

What was the ancient understanding of disease before microbes were known?

Ancient thinkers like Hippocrates and Thucydides proposed that diseases were caused by internal and environmental factors, not the supernatural. Thucydides also described immunity after surviving infection.

Spontaneous generation

The belief that living organisms could arise from nonliving matter (e.g., maggots from meat or mice from grain).

Biogenesis

States that life comes only from pre-existing life.

Louis Pasteur

Disproved spontaneous generation (1861 swan-neck flask experiment disproved spontaneous generation: sterilized broth remained free of microbes until exposed to airborne contaminants); developed pasteurization and vaccines.

Florence Nightingale

Linked sanitation to lower infection rates.

Joseph Lister

Introduced aseptic surgery using carbolic acid.

Robert Koch

Formulated postulates linking specific microbes to diseases.

Edward Jenner

Created the first vaccine (cowpox → smallpox immunity).

Alexander Fleming

Discovered penicillin and warned about antibiotic resistance.

Three domains of life

Bacteria, Archaea, and Eukarya.

Carl Linnaeus

Developed the binomial nomenclature system (modern system of naming organisms)

Binomial nomenclature

Scientific name; each species is identified by a two-part Latin name: Genus (capitalized) + species (lowercase), both italicized (e.g., Staphylococcus aureus).

Bacteria

Unicellular prokaryotes with no nucleus or membrane-bound organelles; most have peptidoglycan cell walls and reproduce by binary fission.

Archaea

Single-celled prokaryotes that often live in extreme environments; lack peptidoglycan in their cell walls and have unique membrane lipids and DNA + RNA sequences more similar to eukaryotes.

Algae

Photosynthetic eukaryotes that can be unicellular or multicellular; contain chlorophyll and produce oxygen through photosynthesis.

Protozoa

Unicellular eukaryotic organisms that move using cilia, flagella, or pseudopodia; many are free-living, others parasitic.

Fungi

Eukaryotic decomposers; can be unicellular (yeasts) or multicellular (molds); cell walls contain chitin.

Helminths

Multicellular parasitic worms (e.g., roundworms, tapeworms) that infect hosts in their larval or egg stages; studied in microbiology because their early forms are microscopic.

Viruses

Non living entities; acellular infectious agents made of DNA or RNA and a protein coat (sometimes a lipid envelope); can only replicate inside a host cell.

Why are Koch’s postulates important?

Led to the development of microbiology techniques we still use today (culturing on medium)

1. Koch’s postulates

The suspected pathogen is found in all cases of the disease.

2. Koch’s postulates

It can be isolated and grown in pure culture.

3. Koch’s postulates

The cultured organism causes the same disease in a healthy host.

4. Koch’s postulates

The same organism can be re-isolated from that host.

Three subatomic particles and their charges

• Protons: Positive charge, located in the nucleus.

• Neutrons: Neutral charge, located in the nucleus.

• Electrons: Negative charge, orbit the nucleus.

Atoms organized on the periodic table

Each element is defined by its atomic number (protons) and atomic mass (protons + neutrons). The table arranges elements by increasing atomic number and recurring chemical properties.

Element

A pure substance made of only one kind of atom (e.g., O₂).

Compound

A molecule formed by two or more different elements bonded together (e.g., H₂O, NaCl).

Ionic bond

A bond formed by the transfer of electrons between a metal and a nonmetal, producing charged ions that attract each other (e.g., Na⁺Cl⁻).

Covalent bond

A bond formed by the sharing of electrons between two nonmetal atoms. Can be polar (unequal sharing) or nonpolar (equal sharing).

Single bond

1 shared pair of electrons (H–H)

Double bond

2 shared pairs (O=O)

Triple bond

3 shared pairs (N≡N)

Hydrogen bonds

Weak attractions between a slightly positive hydrogen atom and a slightly negative oxygen or nitrogen atom. They stabilize DNA, protein folding, and give water its unique properties (cohesion, adhesion, high heat capacity).

Hydrophilic

means “water-loving.” These molecules are polar or charged, allowing them to form hydrogen bonds with water and dissolve easily.
Examples: salts, sugars, amino acids with polar side chains.

Hydrophobic

means “water-fearing.” These molecules are nonpolar and cannot form hydrogen bonds with water, so they cluster together instead of dissolving.
Examples: lipids, oils, and nonpolar hydrocarbons.

Four major elements essential for life

Carbon, Hydrogen, Oxygen, and Nitrogen (CHON). They form the backbone of carbohydrates, proteins, lipids, and nucleic acids.

Functional groups

Specific groups of atoms that give molecules characteristic chemical properties and reactivity.

Amino group (-NH₂)

Acts as a base; can accept a hydrogen ion to become -NH₃⁺. Found in amino acids and proteins.

Carboxyl group (-COOH)

Acts as an acid; donates hydrogen ions (H⁺). Found in amino acids and fatty acids.

Hydroxyl group (-OH)

Polar; forms hydrogen bonds and increases solubility in water. Found in alcohols and carbohydrates.

Carbonyl group (C=O)

Found in aldehydes and ketones; makes molecules more reactive in metabolic reactions.

Phosphate group (-PO₄)

Negatively charged; stores and transfers energy (as in ATP and nucleotides).

What are carbohydrates made of, and what is their general formula?

Made of carbon, hydrogen, and oxygen in a 1:2:1 ratio (CₙH₂ₙOₙ).

How do simple sugars (glucose) form complex carbohydrates?

Monosaccharides link via glycosidic bonds through dehydration synthesis to form polysaccharides.

Main functions of carbohydrates

Provide quick energy, energy storage (as starch/glycogen), and structural support (as cellulose or chitin).

What are lipids composed of?

Mostly carbon and hydrogen; include fats, phospholipids, and steroids. They’re hydrophobic and store energy.

Fatty acids

long hydrocarbon chains with a carboxyl group (-COOH) at one end.
They are the building blocks of many lipids, including triglycerides and phospholipids. Not a true monomer.

How do fatty acids form triglycerides and phospholipids?

They link to glycerol through ester bonds formed via dehydration synthesis.

Saturated fats

No double bonds; straight chains; solid at room temperature.

Unsaturated fats

One or more double bonds; kinked chains; liquid at room temperature.

Cholesterol

A steroid important for membrane stability and hormone synthesis.

Waxes

Protective lipid coatings that provide waterproofing and prevent dehydration.

Main functions of lipids

Energy storage, insulation, and cell membrane structure (phospholipid bilayer).

Building blocks of proteins

Amino acids linked by peptide bonds formed between the amino group of one and the carboxyl group of another.

Main functions of proteins

Structural (muscle, keratin), enzymatic (catalysis), and signaling (hormones).

Monomers of nucleic acids, and how are they linked?

Nucleotides, connected by phosphodiester bonds between the 5′ phosphate and 3′ hydroxyl groups.

Two types of nucleic acids and their roles

• DNA: Double-stranded, stores genetic information.

• RNA: Single-stranded, acts as a messenger and helps with protein synthesis.

Cohesion

the attraction between molecules of the same substance—caused by hydrogen bonding in water. It allows water molecules to “stick” to each other, giving rise to surface tension.

Adhesion

the attraction between water molecules and different substances. It helps water climb surfaces (capillary action), such as moving through plant xylem or lab capillary tubes.

How do cohesion and adhesion work together

Cohesion holds water molecules together, while adhesion allows them to cling to other materials. Together, they enable capillary action, where water can move against gravity through narrow spaces.

Dehydration synthesis

A chemical reaction that builds larger molecules by joining smaller monomers and removing a water molecule (H₂O). Example: forming peptide, ester, or glycosidic bonds.

Hydrolysis

Breaks down larger molecules into smaller subunits by adding water to split bonds. It’s the reverse of dehydration synthesis.

Why are dehydration and hydrolysis reactions important in biology?

They allow living organisms to assemble macromolecules (dehydration) and break them down for energy or recycling (hydrolysis).

Monomer

a small, single subunit molecule that can bond chemically with other monomers to form a larger structure called a polymer.
Examples: glucose (monomer of starch), amino acid (monomer of protein), nucleotide (monomer of nucleic acids).

Polymer

a large molecule made of repeating monomer units linked together by covalent bonds, often formed through dehydration synthesis.
Examples: polysaccharides, proteins, nucleic acids.

Six main parts of cell theory

• All living things are made of cells.

• Cells are the basic units of structure and function in living organisms.

• All cells come from preexisting cells.

• Cells contain hereditary information (DNA) passed to offspring.

• All cells are similar in chemical composition and metabolic activities.

• Cellular activity depends on the activities of subcellular structures.

Seven traits of life

• Order/organization

• Response to environment

• Growth and development

• Energy processing

• Homeostasis

• Reproduction

• Evolutionary adaptation

Three main structural features common to all cells

• Cell membrane: Acts as a barrier, regulating what enters and exits.

• DNA: Genetic material controlling cell functions.

• Cytosol (cytoplasm): Fluid matrix where organelles reside and reactions occur.

Prokaryotes

Lack a nucleus and membrane-bound organelles; DNA is in the nucleoid.

Eukaryotes

Have a true nucleus and membrane-bound organelles.

Components of prokaryotic cell walls

• Contain peptidoglycan (Gram-positive: thick; Gram-negative: thin + outer membrane).

• May include acid-fast cell walls with mycolic acids.

Acid-fast cell walls

Cell walls containing mycolic acids, making them waxy and resistant to chemicals and stains (e.g., Mycobacterium).

Glycocalyx, and what are its two forms

A sticky outer layer made of polysaccharides or proteins; forms:

• Capsule: Organized, firmly attached (prevents phagocytosis).

• Slime layer: Loosely attached, aids in biofilm formation.

Biofilms

Communities of microorganisms attached to surfaces, embedded in a shared matrix; provide protection and nutrient access.

Flagella

Movement (motility)

Fimbriae

Attachment to surfaces.

Pili

DNA transfer during conjugation

Organelles

Specialized membrane-bound structures within a eukaryotic cell that perform specific functions.

Nucleus, and what does it contain?

The control center of the cell; contains DNA organized as chromosomes, surrounded by a nuclear envelope with pores.

Ribosomes, and what do they do?

Sites of protein synthesis; can be free in cytoplasm or attached to rough ER.

Rough endoplasmic reticulum (RER)

RER is covered with ribosomes and synthesizes and processes proteins for secretion or membranes.

Smooth ER (SER)

Lacks ribosomes; synthesizes lipids, phospholipids, and steroids; also detoxifies.

Golgi apparatus

Modifies, sorts, and packages proteins and lipids from the ER into vesicles for transport.

Vesicles

Small membrane sacs that transport materials between organelles or to the cell surface.

Lysosomes

Contain digestive enzymes for waste and pathogens.

Peroxisomes

Break down fatty acids and detoxify hydrogen peroxide.

Cytoskeleton

A network of protein fibers (microfilaments, intermediate filaments, microtubules) that maintain cell shape, movement, and transport.

Mitochondria

are the site of ATP production via cellular respiration.

Endosymbiotic theory

Mitochondria originated as free-living prokaryotes engulfed by ancestral eukaryotes.

Eukaryotic cell walls

Composed of cellulose (plants/algae) or chitin (fungi); absent in animal cells.

What are flagella and cilia, and how do they differ?

Both are microtubule-based structures for movement.

• Flagella: Long, whip-like (few per cell).

• Cilia: Short, numerous, move fluid across surfaces.

Main components of the cell membrane

• Phospholipids: Form bilayer with hydrophobic tails and hydrophilic heads.

• Proteins: Transport, signaling, and structural support.

• Cholesterol: Stabilizes membrane fluidity.

What factors affect membrane fluidity?

• Temperature: Higher = more fluid; lower = less fluid.

• Fatty acid saturation: Unsaturated fats increase fluidity; saturated fats decrease it.

What are integral and peripheral proteins?

• Integral proteins: Span the membrane; involved in transport and signaling.

• Peripheral proteins: Loosely attached to membrane surfaces; involved in structure and communication.

What is the difference between active and passive transport?

• Passive transport: No energy required; moves molecules down concentration gradient.

• Active transport: Requires ATP; moves molecules against gradient.

Simple diffusion

Passive transport movement of small, nonpolar molecules (like O₂, CO₂) directly across the membrane down the gradient.

Osmosis

The diffusion of water across a selectively permeable membrane from low solute to high solute concentration.

Facilitated diffusion

Passive transport that uses channel or carrier proteins to move larger or polar molecules (e.g., glucose).