Microbiology Exam 1

What are effective learning strategies for microbiology?

Spaced repetition/practice, recall activities, elaboration, concrete examples, and visuals.

What makes a resource reliable?

It is peer reviewed, up to date, and from a credible organization.

What are reliable resources for learning microbiology?

Biology textbook, CDC, National Institutes of Health, American Society for Microbiology, Microbiology Teacher, and the assigned book.

What are the three domains of life?

Bacteria, Archaea, and Eukarya.

What are the main categories of microorganisms?

Bacteria, archaea, protozoa, algae, fungi, helminths (worms), and viruses. Viruses are not cellular but are included in microbiology.

What is binomial nomenclature?

A scientific naming system using two names: a genus and a specific epithet. Example: Escherichia coli.

Why are microorganisms important to life on Earth?

They are foundational to ecosystems and essential for human health, agriculture, and the environment.

What are common bacterial cell morphologies?

Coccus, bacillus, vibrio, coccobacillus, spirillum, and spirochete.

What is the nucleoid?

A DNA-containing region that directs the cell and codes for proteins.

What are 70S ribosomes made of and what is their function?

They are made of protein and RNA and are the sites of protein synthesis.

What is a plasmid?

A circular, double-stranded DNA molecule containing extra genes.

What is a pilus?

A long, hollow appendage used by some bacteria to transfer DNA to other cells.

What is a bacterial flagellum?

A protein structure used for motility.

What is taxis?

Active, intentional, directional movement toward or away from an environmental stimulus.

What is Brownian motion?

Passive, unintentional, random movement of particles caused by collisions with surrounding fluid molecules.

What are fimbriae?

Fine, hairlike bristles extending from the cell surface that help with adhesion to cells or surfaces.

What are inclusions/granules?

Structures that store nutrients in dense crystals for later use.

What is the bacterial cell wall?

A semirigid casing that provides structural support and shape.

What is the cell membrane?

A thin sheet of lipid and protein that surrounds the cytoplasm and controls movement of materials into and out of the cell.

What is the Gram-negative outer membrane?

A membrane made of lipids, proteins, and lipopolysaccharides that controls material flow; some portions are toxic to mammals if released.

What is an endospore?

A dormant body that allows some bacteria to survive harsh environments.

What is the cytoplasm?

The water-based solution that fills the cell.

How do Gram-negative and Gram-positive bacteria differ?

Gram-negative bacteria have three layers, stain red, and have LPS. Gram-positive bacteria have two layers, stain purple, and have teichoic and lipoteichoic acids.

What structures do Gram-positive and Gram-negative cells have in common?

A peptidoglycan layer and at least one membrane.

What structures distinguish Gram-positive and Gram-negative cells?

Gram-positive: teichoic/lipoteichoic acids and two layers. Gram-negative: LPS on the outer membrane and three layers.

How do the peptidoglycan layers differ between Gram-positive and Gram-negative bacteria?

Gram-positive has a thick peptidoglycan layer and Gram-negative has a thin peptidoglycan layer.

What are Mycoplasmas?

Bacteria related to Gram-positive bacteria that lack a cell wall and contain sterols in the membrane for stability.

What is characteristic of acid-fast bacteria?

They are like Gram-positive bacteria and have a waxy lipid layer bound to peptidoglycan that provides environmental protection.

What features allow endospores to survive extreme conditions?

Resistance to extreme temperatures and radiation, dehydration, dormancy, and no metabolic activity or growth.

What is sporulation?

The process of endospore formation.

What is the function of the nucleus?

It stores DNA.

What is the function of mitochondria?

ATP production and aerobic respiration.

What is the function of the Golgi apparatus?

Packaging, sorting, and shipping proteins in vesicles.

What is the function of the endoplasmic reticulum?

It synthesizes and folds proteins and forms membranes.

What is the function of chloroplasts?

In algae and plants, they carry out photosynthesis and ATP production.

What is the function of lysosomes?

They degrade waste materials and damaged organelles.

What is the function of 80S ribosomes?

They make proteins.

What is the function of the cytoskeleton?

It gives the cell structure.

What is the function of eukaryotic flagella or cilia?

Motility.

What is the function of the eukaryotic cell membrane?

It regulates movement of substances and provides structural support.

What is the function of a eukaryotic cell wall?

In cells that have one, it provides structural support, protection, and helps maintain shape.

What are general characteristics of algae?

They may be single-celled or multicellular and usually have cellulose cell walls; diatoms have silica.

What are general characteristics of protozoa?

They are single-celled, lack a cell wall, and have trophozoite (active) and cyst (dormant) forms.

What are general characteristics of fungi?

They may be single-celled or multicellular, have chitin cell walls, occur as yeast or mold, and have ergosterol in the cell membrane.

What is a unique characteristic of Eukarya?

They have 80S ribosomes.

What is a unique characteristic of Bacteria?

They have 70S ribosomes.

What is a unique characteristic of Archaea?

They have 70S ribosomes whose structure is like 80S ribosomes.

How do bacterial, archaeal, and eukaryotic membranes differ?

Bacteria and Eukarya have ester linkages to phospholipids; Archaea have ether linkages.

How do bacterial, archaeal, and eukaryotic cell walls differ?

Bacteria have peptidoglycan; Archaea lack peptidoglycan and have protein or glycoprotein walls; Eukarya lack peptidoglycan and may have cellulose or chitin.

How do bacterial, archaeal, and eukaryotic flagella differ?

Bacterial flagella use many proteins and rotate like a motor; archaeal flagella use multiple filament proteins and rotate; eukaryotic flagella are a multiprotein complex that move like waves.

Why do eukaryotic cells have organelles while bacterial and archaeal cells generally do not?

Eukaryotic cells are larger, so organelles help compartmentalize transportation and synthesis of cell components that diffusion cannot efficiently disperse.

How do pili/fimbriae help microbial survival?

They allow microbes to attach to surfaces or host cells; losing them can reduce colonization.

How does a capsule help microbial survival?

It protects microbes from toxins and drying out; losing it can increase dehydration and vulnerability.

How does LPS help Gram-negative bacteria?

It helps stabilize the cell membrane; losing it can make the membrane unstable and more susceptible to damage.

How do endospores help microbial survival?

They allow microbes to survive harsh environments; losing spore formation decreases survival under harsh conditions.

How do flagella help microbial survival?

They allow movement in aqueous environments toward favorable conditions; losing them can reduce movement toward favorable conditions.

What two characteristics do all living cells share?

A cell membrane and DNA.

What chemicals enter cells for metabolism?

Carbon, nitrogen, oxygen/hydrogen from water, phosphorus, sulfur, and trace elements such as K, Mg, Ca, Na, and Fe.

How do chemicals enter cells?

Passive transport: diffusion, facilitated diffusion, and osmosis. Active transport: simple transport, group translocation, and ABC transport.

What is the role of electron carriers in metabolism?

They bind and shuttle high-energy electrons between compounds in metabolic pathways.

What are energy-rich compounds?

Energy currency of the cell that safely stores energy and releases it as needed.

What is the role of enzymes in metabolism?

They help control cellular metabolism.

What is substrate-level phosphorylation?

A phosphate group is removed from an organic molecule and directly transferred to ADP, producing ATP.

Where does substrate-level phosphorylation occur?

Glycolysis and the Krebs cycle.

What is oxidative phosphorylation?

ATP production during respiration using energy from electron transport.

What is photophosphorylation?

ATP production using energy from light.

What is aerobic respiration?

Aerobic catabolism in which an electron donor is oxidized with O2.

What is anaerobic respiration?

Anaerobic catabolism in which an electron donor is oxidized with another compound as the electron acceptor.

What is fermentation?

Anaerobic catabolism in which organic compounds donate and accept electrons.

What is chemolithotrophy?

Oxidation of inorganic compounds such as H2, H2S, and NH4+.

What is oxygenic photophosphorylation?

Light-driven phosphorylation that uses water as the electron donor, produces oxygen, and involves two photosystems.

What is anoxygenic photophosphorylation?

Light-driven phosphorylation that does not produce oxygen, uses alternative electron donors, and involves one photosystem.

What is the proton motive force (PMF)?

The electrochemical gradient of H+ across a membrane that stores energy for ATP synthesis and other cellular processes.

How is the proton motive force generated?

An electron transport chain uses energy from electron transfer to pump protons across a membrane, creating an electrochemical gradient.

How does ATP synthase use the PMF?

Protons flow back across the membrane through ATP synthase, providing energy to convert ADP and phosphate into ATP.

Where does glycolysis occur in prokaryotic and eukaryotic cells?

Cytoplasm in both.

Where does respiration occur in prokaryotic and eukaryotic cells?

Prokaryotes: cytoplasm. Eukaryotes: mitochondrial matrix.

Where does the electron transport chain occur in prokaryotic and eukaryotic cells?

Prokaryotes: cell membrane. Eukaryotes: mitochondrial inner membrane.

What are examples of anabolic pathways?

Carbohydrate synthesis and amino acid synthesis.

What is amphibolism?

The connection of catabolic and anabolic pathways to improve cell efficiency by allowing pathways to be used together.

What determines an organism's metabolic lifestyle?

Its energy source and carbon source.

What is a chemoheterotroph?

An organism that gets energy from chemicals and carbon from organic compounds.

What is a chemolithoautotroph?

An organism that gets energy from inorganic chemicals and carbon from CO2.

What is a photoheterotroph?

An organism that gets energy from light and carbon from organic compounds.

What is a photoautotroph?

An organism that gets energy from light and carbon from CO2.

Why are microbial fermentation products important to food and beverage production?

Fermentation gives products flavor and quality and helps with preservation and food safety.

What foods and beverages use microbial fermentation?

Bread, cheese, yogurt, wine, and beer.

What is mitosis?

Diploid division of a cell that produces an exact copy; asexual reproduction.

What is meiosis?

Haploid division that halves chromosome number and is associated with sexual reproduction.

What is binary fission?

Asexual cell division following enlargement of a cell to twice its minimum size.

What is budding?

Unequal asexual division that forms a daughter cell.

How can environmental factors inhibit microbial growth?

Extreme temperature, pH, pressure, oxygen conditions, or salt concentration can disrupt membrane stability, enzyme activity, nucleic acids, and the proton motive force.

What happens to membranes and nucleic acids under unfavorable environmental conditions?

They can become unstable; at more extreme conditions proteins can denature, membranes can be disrupted, and nucleic acids can be denatured.

What factors can be used to predict microbial growth behavior?

Temperature, available nutrients, aeration/oxygen level, and other environmental conditions.

What is the structure of a biofilm?

An assemblage of microbial cells adhered to a surface.

What conditions favor biofilm formation?

Conditions that support microbial growth and allow cells to attach to a surface; the notes do not provide a more specific list.

What are the stages of biofilm formation and maturation?

Attachment, Colonization, Development, Active Dispersal

What are differential gene expression and quorum sensing in a biofilm?

Quorum sensing (communications using chemical signals) allows bacteria to communicate and detect population density, which can trigger differential gene expression (turning on or off different genes) and coordinated behaviors that help form and maintain the biofilm.

What is an example of a beneficial and detrimental biofilm?

Beneficial: wastewater treatment biofilms, food production

Detrimental: dental plaque, kidney stones

How is the rate of bacterial growth measured?

The length of the generation time (generation time(g)= duration of exponential growth(t)/ number of generations during exponential growth(n))