Microbiology Exam 2: Antimicrobial Chemotherapy, Microbial Metabolism, and Bacterial Genetics

Comprehensive fill-in-the-blank review flashcards covering antimicrobial chemotherapy, metabolic catabolism and anabolism, and bacterial genome replication and gene expression.

The ability of an antimicrobial drug to harm a microbe without harming the host is referred to as __________.

selective toxicity

An example of a cellular target found in bacterial cell walls but absent in human cells is __________.

peptidoglycan

Fungal and protozoan infections are harder to treat than bacterial infections because their cells are __________, making them very similar to human cells.

eukaryotes

Viruses are difficult to target without damaging the host because they rely on the __________ to reproduce.

host cell's machinery

Antimicrobial drugs designed specifically to target parasitic worms are classified as __________.

antihelminthics

An antibiotic that targets a wide variety of bacteria and can affect both harmful and helpful flora is categorized as a __________ antibiotic.

broad-spectrum

An antimicrobial drug that directly kills susceptible bacterial cells is known as __________.

bactericidal

An antimicrobial drug that stops bacterial multiplication and cell growth without killing them outright is described as __________.

bacteriostatic

Antibiotics can selectively inhibit bacterial protein synthesis because bacteria possess $70\text{S}$ ribosomes, whereas human cytoplasmic ribosomes are __________.

$$80\text{S}$$

Antimicrobials that target the bacterial __________ can disrupt normal transport or cause essential molecules to leak out.

cell membrane

When a bacterium modifies the cellular receptor or enzyme that an antibiotic normally binds to, it is demonstrating the resistance mechanism of altering the __________.

drug's target

A bacterial transport protein that actively removes antibiotics from the cell to prevent them from reaching effective concentrations is called an __________.

efflux pump

Plasmids that carry multiple antibiotic resistance genes and can spread resistance to several drugs at once are designated as __________.

R plasmids

The movement of genetic information between contemporary bacterial cells rather than from parent to offspring is called __________.

horizontal gene transfer

The term used to describe all the chemical reactions that take place within a living cell is __________.

metabolism

The metabolic process that breaks larger molecules down into smaller ones while releasing energy is __________.

catabolism

Organisms that obtain their carbon, energy, and electrons entirely from organic compounds such as sugars, proteins, and fats are called __________.

chemoorganoheterotrophs

Organisms that obtain electrons from inorganic substances are designated as __________.

chemolithotrophs

Unlike respiration, fermentation produces a small amount of $\text{ATP}$ and does not use an __________.

electron transport chain

The fundamental purpose of fermentation pathways in microbial cells is to regenerate __________ so that glycolysis can continue.

$$\text{NAD}^+$$

In respiration, the membrane protein that synthesizes $\text{ATP}$ using the energy of an incoming proton flow is __________.

$\text{ATP}$ synthase

In aerobic respiration, the molecule that serves as the final electron acceptor at the end of the electron transport chain is __________.

$$\text{O}_2$$

During fermentation, $\text{NADH}$ delivers its electrons to an organic molecule, such as __________.

pyruvate

The direct transfer of a phosphate group from a phosphorylated metabolic intermediate to $\text{ADP}$ to generate $\text{ATP}$ is known as __________.

substrate-level phosphorylation

For each molecule of glucose processed through glycolysis, the net yield is two molecules of $\text{NADH}$, two molecules of pyruvate, and __________ molecules of $\text{ATP}$.

$$2$$

An alternate glucose-breakdown pathway utilized by some bacteria that yields only $1\text{ ATP}$ per glucose alongside two pyruvates is the __________.

Entner-Doudoroff pathway

The pentose phosphate pathway serves the cell by processing sugars and producing precursor metabolites along with __________, which supplies reducing power for biosynthesis.

$$\text{NADPH}$$

Before entering the tricarboxylic acid (TCA) cycle, the pyruvate generated during glycolysis is converted into __________.

acetyl-CoA

Because each glucose produces two pyruvate molecules, the TCA cycle must run __________ per molecule of glucose entering glycolysis.

twice

As electrons flow through the electron transport chain, energy is released to pump $\text{H}^+$ ions across the membrane, forming a __________.

proton gradient

Compared to aerobic respiration, anaerobic respiration uses an alternate electron acceptor and yields __________ $\text{ATP}$.

less

The metabolic pathway category that utilizes energy and smaller molecules to build larger cellular components is called __________.

anabolism

Small carbon molecules generated during catabolism that are diverted away from further breakdown to be used as building blocks are called __________.

precursor metabolites

The complete complement of genetic information contained in an organism is known as its __________.

genome

The experiment by __________ showed that heat-treated disease-causing bacteria could pass on traits to living harmless bacteria, discovering transformation.

Griffith

Avery, MacLeod, and McCarty demonstrated that the transforming substance was $\text{DNA}$ because treating samples with the enzyme __________ prevented transformation from occurring.

DNase

Hershey and Chase proved $\text{DNA}$ was the genetic material by using radioactive tracers to show that bacteriophage $\text{DNA}$ entered the bacterial cell while labeled __________ remained outside.

protein

In a nucleic acid chain, individual nucleotides are connected to one another by covalent linkages called __________.

phosphodiester bonds

$\text{DNA}$ replication is classified as __________ because each newly synthesized double helix preserves one original parental strand and one newly formed strand.

semiconservative

Bacterial chromosome replication starts at a specific site designated as the __________.

origin of replication

$\text{DNA}$ polymerase cannot synthesize a strand de novo; it requires a primer that supplies a free __________ to attach the incoming nucleotide.

$$3'\text{-OH}$$

During strand synthesis, $\text{DNA}$ polymerase can add nucleotides exclusively to the __________ of the growing strand.

$$3'\text{ end}$$

In bacteria, $\text{RNA}$ polymerase requires the binding of a regulatory protein called the __________ to recognize and bind the promoter.

sigma factor

Bacterial promoters characteristically possess two conserved recognition sites located at the __________ positions relative to the start of transcription ($+1$).

$$-35\text{ and }-10$$

During transcription, $\text{RNA}$ polymerase synthesizes a new $\text{RNA}$ transcript in the $5' \rightarrow 3'$ direction while reading the __________ strand in the $3' \rightarrow 5'$ direction.

template

Transcription termination in bacteria proceeds via either Rho-dependent mechanisms or __________ mechanisms.

Rho-independent

A cluster of bacterial genes with related functions that are controlled and transcribed together from a single promoter is known as an __________.

operon

An $\text{mRNA}$ molecule that encodes information for several different proteins translated from a single transcript is referred to as __________.

polycistronic RNA

The standard translation start codon is $\text{AUG}$, which in bacteria instructs the ribosome to insert the specialized amino acid __________.

formylmethionine

The standard codons $\text{UAA}$, $\text{UAG}$, and $\text{UGA}$ do not specify any amino acid and are referred to as __________.

stop codons

In bacteria, the small ribosomal subunit aligns with the ribosome-binding site on $\text{mRNA}$ through base pairing mediated by __________.

$$16\text{S rRNA}$$

During translation elongation, an incoming charged tRNA carrying an amino acid first enters the ribosomal __________ site.

$$\text{A}$$

During the initiation phase of translation, the initiating tRNA carrying fMet occupies the __________ site of the ribosome.

$$\text{P}$$

When a translation stop codon enters the ribosomal $\text{A}$ site, a protein known as a __________ binds to cause peptide release and ribosomal dissociation.

release factor

In bacteria, translation can occur simultaneously on an $\text{mRNA}$ strand while it is being transcribed because the cell lacks a __________.

membrane-bound nucleus

The four primary cellular mechanisms by which bacteria exhibit antimicrobial resistance are altering the drug target, pumping the drug out, enzymatically altering the drug, and __________.

enzymatically degrading the antibiotic

When a resistant bacterium produces an enzyme that chemically destroys an antibiotic before it can act, it is using the resistance mechanism of __________.

enzymatic degradation

When a microbe synthesizes an enzyme that chemically modifies an antibiotic's structure so that it can no longer function, it is demonstrating __________.

enzymatic alteration

An antimicrobial that acts against only a limited or specific group of bacteria, sparing many helpful flora, is classified as a __________ antibiotic.

narrow-spectrum

Antibacterial drugs that interfere with $\text{DNA}$ replication or $\text{RNA}$ transcription directly inhibit microbial __________.

nucleic acid synthesis

Antimicrobial drugs that block specific enzymatic steps needed to synthesize essential cellular products target bacterial __________.

metabolic pathways

When antibiotic exposure kills susceptible cells, leaving surviving resistant mutants to reproduce with less competition, resistance spreads via __________.

natural selection

The multiprotein cellular complex that convenes at the replication fork to carry out bacterial $\text{DNA}$ replication is called the __________.

replisome

To synthesize a complementary strand, $\text{DNA}$ polymerase requires free deoxynucleotides, a template strand, and a primer providing a free __________.

$3'\text{-OH}$ group

The process of transcription proceeds sequentially through three distinct stages: initiation, elongation, and __________.

termination

During the elongation phase of transcription, $\text{RNA}$ polymerase synthesizes $\text{RNA}$ in the $5' \rightarrow 3'$ direction while reading the template strand in the __________ direction.

$$3' \rightarrow 5'$$

Like transcription, translation occurs in three distinct sequential steps: initiation, elongation, and __________.

termination

In the ribosome, the aminoacyl site ($\text{A}$ site) functions primarily to receive an incoming __________.

charged tRNA

During translation elongation, the tRNA holding the growing polypeptide chain is positioned within the ribosomal __________ site.

$\text{P}$ site

During translation elongation, an uncharged tRNA is shifted into the __________ site just before it exits the ribosome.

$\text{E}$ site

In contrast to polycistronic $\text{mRNA}$, an $\text{mRNA}$ transcript that contains the genetic instructions for synthesizing only a single protein is described as __________.

monocistronic

The flexibility in base pairing observed between the $3'$ position of an $\text{mRNA}$ codon and the $5'$ position of a tRNA anticodon is known as __________.

wobble

While $\text{NADH}$ is primarily utilized to transfer electrons to generate energy in catabolic pathways, __________ is primarily used to supply reducing power for biosynthetic (anabolic) reactions.

$$\text{NADPH}$$

The three central metabolic pathways that generate precursor metabolites to feed into biosynthesis are glycolysis, the pentose phosphate pathway, and the __________.

TCA cycle

Because bacteria lack a membrane-bound nucleus, transcription and translation can occur simultaneously in the cytoplasm, allowing microbes to rapidly synthesize __________.

proteins

The five major cellular targets of antibacterial antibiotics are __________.

cell wall synthesis, protein synthesis, nucleic acid synthesis, cell membrane function, and metabolic pathways

The four primary cellular mechanisms by which bacteria become resistant to antimicrobials are __________.

altering the drug's target, enzymatically degrading the antibiotic, enzymatically altering the antibiotic, and pumping the antibiotic out

The primary products generated from one molecule of glucose during glycolysis are two pyruvates, __________, and a net of $2\text{ ATP}$.

$$2\text{ NADH}$$

Unlike glycolysis which yields $2\text{ ATP}$, the Entner-Doudoroff pathway produces two pyruvates and a net yield of __________ per glucose.

$$1\text{ ATP}$$

During respiration, the TCA cycle oxidizes derivatives of pyruvate to generate precursor metabolites, $\text{ATP}$, $\text{NADH}$, and __________ to transfer electrons to the electron transport chain.

$$\text{FADH}_2$$

In aerobic respiration, when electrons pass through the electron transport chain to oxygen as the final electron acceptor, __________ is formed as a byproduct.

$$\text{H}_2\text{O}$$

The three fundamental nutritional resources that all microbial cells must obtain to power their metabolic activities are energy, electrons, and __________.

carbon

Microbes that use light as their source of energy to power cellular activities are classified as __________.

phototrophs

The flow of genetic information described by the central dogma occurs through three primary sequential processes: $\text{DNA}$ replication, transcription, and __________.

translation

Every nucleotide monomer in $\text{DNA}$ and $\text{RNA}$ consists of three chemical parts: a nitrogenous base, a pentose sugar, and one or more __________.

phosphate groups

The complementary base pairs connecting the two antiparallel strands of a $\text{DNA}$ double helix are held together by __________.

hydrogen bonds

To slow the emergence and spread of antibiotic resistance in bacterial populations, antibiotics should be used __________.

as directed and only when needed