Brock Biology of Microorganisms - Chapters 1, 2, and 3 Exam Review

Flashcard practice deck covering Chapter 1 (The Microbial World), Chapter 2 (Microbial Cell Structure and Function), and Chapter 3 (Microbial Metabolism) from Brock Biology of Microorganisms, 16th Edition.

Microbiologist who first described bacterial cells as 'wee animalcules' in a 1684 manuscript

Antoni van Leeuwenhoek

Microbiologist who developed the enrichment culture technique to isolate specific microbes based on metabolic traits

Martinus Beijerinck

Researcher who compared rRNA sequences across organisms to generate the tree of life and establish the three-domain system

Carl Woese

Scientist who first demonstrated that certain bacteria obtain energy from inorganic compounds (chemolithotrophy)

Sergei Winogradsky

Author who published the first documented description of microorganisms in the 1665 book Micrographia

Robert Hooke

Solid substrates utilized by Robert Koch to culture bacterial cells in his laboratory

Agar, gelatin, and potatoes

Animal model used by Robert Koch to conclusively prove that Mycobacterium tuberculosis causes tuberculosis

Guinea pigs

The first statement of Koch's postulates

The disease-causing organism must always be present in animals suffering from the disease but not in healthy animals.

Three primary concerns that can prevent the fulfillment of Koch's postulates

1. Infected animals do not show the same symptoms as humans.
2. The suspected pathogen is present in healthy humans.
3. An axenic (pure) culture cannot be obtained.

Robert Koch's professional training and the specific bacterial disease he studied to develop the germ theory

He was trained as a physician and studied bacteremia caused by Bacillus anthracis.

Taxonomic group of photosynthetic microorganisms primarily responsible for oxygenating Earth

Cyanobacteria

Shift in the leading causes of death in the United States from the early 1900s to present day

In the early 1900s, infectious diseases were the primary cause of death, whereas today nonmicrobial systemic diseases are the leading cause.

Harmful industrial impact of microorganisms rather than a beneficial application

Biofilm formation in fuel tanks, pipes, and drains

Role of active microbial populations in the rumen of ruminant animals

Fermentation of cellulose (main component of plant cell walls) into usable nutrient sources for the animal

Distinction between the fields of bioremediation and biotechnology

Bioremediation uses microorganisms to clean up contaminated environments (e.g., soil contaminated with carcinogens), while biotechnology uses genetically engineered microbes to produce valuable products (e.g., human insulin).

The three domains in the tree of life

Bacteria, Archaea, and Eukarya (Viruses are excluded as they are not a domain).

Fundamental scientific discovery resulting from Frederick Griffith's transformation experiments with Streptococcus pneumoniae

DNA is the molecular basis of heredity.

Reason why rRNA genes are NOT rapidly changing in sequence during phylogenetic analysis

rRNA genes are highly conserved (slowly evolving) because they perform an essential function in protein synthesis present in all cells.

Method responsible for discovering the majority of phyla in domain Bacteria

Sequencing DNA extracted directly from environmental samples

Three true statements highlighting the diversity of life in Archaea, Bacteria, and microbial Eukarya

1. Domain Archaea contains no known disease-causing pathogens.
2. Bacterial cells can reach sizes up to $700\,\mu\text{m}$ in length.
3. Microbial Eukarya first arose approximately $2\text{ billion}$ years ago.

Historical view of alcohol production prior to Louis Pasteur's work

It was believed to be a purely chemical process rather than one catalyzed by living microorganisms.

Pasteur's experiment demonstrating biological discrimination between optical isomers

Discovery that Aspergillus exclusively metabolizes only one of the two isomeric forms of tartrate.

Viral disease for which Louis Pasteur developed an effective vaccine

Rabies

Principal technical accomplishment of Louis Pasteur's work that was essential to refuting spontaneous generation

Sterilization

Purpose of the swan-necked flask design in Louis Pasteur's spontaneous generation experiments

To allow air to enter while preventing airborne microbes and large debris from contaminating the sterile liquid medium

Cellular process or property that is NOT shared by all living cells

Differentiation (whereas metabolism, evolution, and genetic transcription/translation are universal properties)

Taxis movement relative to chemical or physical gradients

Cells possess the ability to move both toward an attractant gradient and away from a repellent gradient.

Specific taxis used by cyanobacteria to move toward a more hydrated environment

Hydrotaxis

Structural flagellar arrangement responsible for motility in Escherichia coli

Peritrichous flagella

Three structural and operational features that distinguish archaella from bacterial flagella

1. Archaella are smaller in diameter than flagella.
2. Archaella are solid (not hollow).
3. Archaellar rotation is driven by ATP hydrolysis rather than proton motive force.

Interpretation of a capillary tube experiment where most cells move away but a few enter the tube

The chemical acts as a repellent to most cells in the culture, but an attractant to the specific cells that entered the tube.

Chemical nature of bacterial fimbriae and pili

Both structures are composed of proteins.

Bacterial surface structure directly involved in genetic exchange (conjugation)

Pili (or pilus)

Three recognized functions of pili

Cell adhesion, exchange of genetic material (conjugation), and twitching motility (Note: defense by poking holes in other cells is NOT a function).

Three main functions of bacterial capsules or slime layers

1. Development and maintenance of biofilms
2. Evasion of destruction by immune cells
3. Attachment to solid surfaces

Intracellular inclusions hypothesized to orient aquatic bacteria downward toward sediments

Magnetosomes

Basic chemical structure of the cytoplasmic membrane

A phospholipid bilayer with embedded proteins.

Three major functions of the cytoplasmic membrane

1. Selective permeability barrier
2. Protein anchor
3. Energy conservation and consumption (Note: protection from osmotic lysis is performed by the cell wall, not the membrane).

Three cellular processes powered by the proton motive force

1. Transport of molecules across the membrane
2. Cell locomotion (flagellar movement)
3. ATP synthesis

Key structural difference in lipid linkages between archaeal membranes and bacterial/eukaryotic membranes

Archaeal membranes contain ether-linked lipids, whereas bacterial and eukaryotic membranes contain ester-linked lipids.

Reason why defining active transport as 'movement from high to low concentration' is false

Active transport moves molecules against a concentration gradient (from low concentration to high concentration) and requires energy.

Molecular components constituting peptidoglycan

N-acetylglucosamine, N-acetylmuramic acid, and a few amino acids.

Group of microorganisms containing teichoic acids in their cell walls

Gram-positive bacteria

Group of bacteria possessing an outer membrane containing lipopolysaccharides (LPS)

Gram-negative bacteria

Enzyme that cleaves the $\beta-1,4$ glycosidic bonds in peptidoglycan

Lysozyme

Constituents directly involved in peptidoglycan cross-linking in gram-negative bacteria

DAP (diaminopimelic acid) and D-alanine

Defining structural feature of a eukaryotic cell

The nucleus

Cytoskeletal elements constructed from actin monomers

Microfilaments

Location of sterols within eukaryotic cellular architecture

Cell membrane

Reason why stating 'eukaryotic flagella are shorter than prokaryotic flagella' is false

Eukaryotic flagella are typically longer and structurally thicker than prokaryotic flagella.

Three key lines of evidence supporting the endosymbiotic origin of mitochondria and chloroplasts

1. They contain their own circular genomes.
2. Their ribosomes are similar in structure to prokaryotic ribosomes.
3. They replicate independently of the host eukaryotic cell via binary-fission-like division.

Specific chemical compound complexed with dipicolinic acid that functions to dehydrate a developing endospore during sporulation

Calcium

Mechanism by which enzymes catalyze chemical reactions

By lowering the activation energy, thereby increasing the rate of the reaction.

Class of organic molecules from which most coenzymes are structurally derived

Vitamins

Roles of glucose and oxygen during aerobic respiration

Glucose serves as the electron donor (oxidized) and oxygen serves as the electron acceptor (reduced).

Classification of an organism that oxidizes hydrogen gas ($\text{H}\_2$) for energy and fixes carbon dioxide ($\text{CO}\_2$) for carbon

Chemolithoautotroph

Reason why calling the substrate-binding site of an enzyme the 'redox site' is false

The specific site where a substrate binds to an enzyme is called the active site.

Primary energy-rich phosphate compound utilized by cells

ATP

Electron donor in an organism oxidizing $\text{H}\_2$ and reducing nitrate ($\text{NO}\_3^-$) to nitrite ($\text{NO}\_2^-$)

$$\text{H}\_2$$

Classification of molybdenum in oxidation-reduction reactions

Molybdenum is a metallic cofactor/trace element, not an enzyme.

Energy requirement and thermodynamic classification for a reaction with a positive $\Delta G^{0\prime}$

Energy is required, and the reaction is endergonic.

Redox couple that provides the greatest amount of energy for a cell

Glucose and $\text{O}\_2$

Metabolic pathway converting glucose to pyruvate, and the pathway oxidizing pyruvate to $\text{CO}\_2$ in respiration

Glycolysis converts glucose to pyruvate; the citric acid cycle (CAC) oxidizes pyruvate to $\text{CO}\_2$.

Energy source and carbon source utilized by photoautotrophs

Light is used as an energy source and $\text{CO}\_2$ is used as a carbon source.

Mechanism by which NADH and $\text{FADH}\_2$ are reoxidized during respiration

Through the electron transport chain

Key metabolic difference between aerobic vs. anaerobic respiration, and chemolithotrophs vs. chemoorganotrophs

Aerobic and anaerobic respiration use different electron acceptors; chemolithotrophs and chemoorganotrophs use different electron donors.

Reason why anaerobic respiration generates less ATP than aerobic respiration

Oxygen ($\text{O}\_2$) has a more positive reduction potential than alternative electron acceptors, yielding a larger electromotive potential.

Carbon unit length and carrier protein required for fatty acid biosynthesis

Two-carbon molecules (acetyl/malonyl units) along with acyl carrier proteins (ACP)

Two central metabolic pathways providing carbon skeletons for amino acid synthesis

Glycolysis and the citric acid cycle (CAC)

Primary biosynthetic function of gluconeogenesis

Synthesis of glucose and other hexose sugars required for cell wall construction

Molecules into which non-nitrogen-fixing bacteria incorporate ammonia for anabolic pathways

Glutamate and glutamine

Two primary products/functions of the pentose phosphate pathway

Production of pentose sugars (for nucleic acids) and NADPH (for reductive biosynthesis)

Major metabolic purpose of fermentation regarding reducing equivalents

To oxidize NADH back to $\text{NAD}^+$ so that glycolysis can continue producing ATP.

Mechanism by which ATP is generated during fermentation

Substrate-level phosphorylation

Reason why stating 'fermentation products are limited to lactic acid and carbon dioxide' is false

Fermenting organisms produce a wide variety of metabolic end-products, including ethanol, acetate, butyrate, propionate, and mixed acids.

Types of electron donor and acceptor compounds in fermentation versus respiration

Fermentation uses organic compounds as both electron donors and acceptors (internally balanced); respiration oxidizes electron donors with exogenous electron acceptors.

Reason why fermentation has a significantly lower ATP yield compared to aerobic respiration

Fermentation relies solely on substrate-level phosphorylation, whereas aerobic respiration utilizes oxidative phosphorylation via an electron transport chain and proton motive force.

Distinction between fermentation and anaerobic respiration regarding electron transport chains and electron acceptors

Fermentation is NOT a form of anaerobic respiration; fermentation uses organic compounds internally without an electron transport chain, whereas anaerobic respiration requires an electron transport chain and exogenous non-oxygen terminal electron acceptors.