Microbiology Chapters 7, 8, 10, 11, and 12 Study Guide

Comprehensive vocabulary flashcards covering bacterial genetics, gene expression, taxonomy, microbial diversity, and eukaryotic microbiology from Chapters 7, 8, 10, 11, and 12.

DNA (Deoxyribonucleic acid)

A nucleic acid containing deoxyribose sugar and bases A, T, C, and G; usually double-stranded and stores genetic information.

RNA (Ribonucleic acid)

A nucleic acid containing ribose sugar and bases A, U, C, and G; usually single-stranded and helps use genetic information to synthesize proteins.

Gene regulation

The cellular control of when genes are turned on or off and how much gene product is synthesized, conserving energy and allowing adaptation to environmental changes.

Semiconservative replication

The mode of DNA replication in which each newly synthesized DNA molecule consists of one original template strand and one newly formed strand.

Helicase

An enzyme that unwinds and separates the double-stranded DNA template at the origin of replication, creating replication forks.

Primase

An enzyme that synthesizes short complementary RNA primers necessary to initiate DNA synthesis.

DNA polymerase

An enzyme that builds complementary DNA strands in the 5′ to 3′ direction and often proofreads newly added nucleotides.

DNA ligase

An enzyme that seals nicks in the sugar-phosphate backbone and joins Okazaki fragments together on the lagging strand.

Transcription

The process by which RNA polymerase uses a single strand of DNA as a template to synthesize a complementary RNA molecule.

Promoter

A specific nucleotide sequence on DNA that serves as the starting signal where RNA polymerase binds to initiate transcription.

Sigma factor

A bacterial protein that binds to RNA polymerase to facilitate the recognition of specific promoter sequences.

Translation

The biological process in which ribosomes use genetic instructions carried by mRNA to synthesize a polypeptide chain.

Codon

A three-nucleotide sequence in mRNA that encodes a specific amino acid or functions as a termination signal during translation.

Anticodon

A triplet sequence of nucleotides on a tRNA molecule that binds complementarily to a corresponding mRNA codon.

Polycistronic mRNA

A transcript that carries genetic information for multiple distinct proteins, commonly produced by bacterial operons.

Monocistronic mRNA

A transcript that carries the coding sequence for only a single protein, typical of most eukaryotic protein-coding mRNAs.

Mutation

A permanent change in the nucleotide sequence of an organism's DNA, which may be harmful, beneficial, or neutral.

Horizontal gene transfer

The non-vertical transmission of genetic material between organisms of the same or different species through transformation, transduction, or conjugation.

Genotype

The specific genetic makeup and sequence of alleles possessed by an organism.

Phenotype

The observable physical and biochemical characteristics of an organism, resulting from its genotype interacting with the environment.

Auxotroph

A mutant microorganism that has lost the ability to synthesize an essential nutrient and requires it supplemented in the growth medium.

Prototroph

A wild-type microorganism that possesses the ability to synthesize all essential cellular compounds from a minimal, basic nutrient medium.

Silent mutation

A base substitution that changes the nucleotide sequence of a codon without altering the resulting amino acid incorporated into the protein.

Missense mutation

a type of point mutation where a single nucleotide change in a DNA sequence causes a different amino acid to be incorporated into the resulting protein during translation

Nonsense mutation

A base substitution that converts an amino-acid-specifying codon into a premature stop codon, typically producing a truncated, nonfunctional protein.

Frameshift mutation

A mutation caused by the insertion or deletion of nucleotides in numbers not divisible by three, changing the downstream reading frame of codons.

Base analogs

Chemical mutagens with structural similarity to normal nitrogenous bases that can be incorporated into DNA, leading to base mispairing.

Intercalating agents

Planar chemical mutagens, such as acridine dyes, that wedge between adjacent base pairs in DNA, causing insertions or deletions during replication.

Transformation

The horizontal gene transfer process in which a competent bacterial cell takes up free, naked DNA from the surrounding environment.

Competent cell

A bacterial cell in a physiological state that allows it to take up extracellular naked DNA from its environment.

Transduction

The transfer of bacterial DNA from a donor cell to a recipient cell mediated by an accidental packaging error during bacteriophage replication.

Conjugation

A mechanism of horizontal gene transfer that involves direct physical cell-to-cell contact to transfer DNA from a donor to a recipient bacterium.

Core genome

The set of conserved genes shared by all members of a given bacterial species or group, governing essential cellular survival functions.

Mobile gene pool

The variable fraction of a bacterial genome composed of mobile genetic elements, such as plasmids, transposons, and phage DNA, that can transfer between cells.

Plasmid

A small, extrachromosomal, usually circular DNA molecule that replicates independently of the bacterial chromosome and often carries nonessential genes.

Taxonomy

The branch of science concerned with the identification, classification, and nomenclature of living organisms.

Binomial nomenclature

The formal two-part naming system for organisms, consisting of an italicized, capitalized genus name followed by an italicized, lowercase species epithet.

NAATs (Nucleic Acid Amplification Tests)

Molecular diagnostic methods, including PCR, that detect microorganisms by copying and amplifying specific target DNA or RNA sequences.

16S rRNA gene sequencing

A genotypic identification method comparing conserved and variable regions of the 16S ribosomal RNA gene to classify bacteria and Archaea.

Serotyping

A phenotypic method for distinguishing bacterial strains based on specific antigen-antibody reactions against microbial surface antigens.

Phage typing

A phenotypic strain identification method that determines the specific susceptibility profile of a bacterial isolate to a panel of known bacteriophages.

Pulsed-field gel electrophoresis (PFGE)

A molecular typing technique that uses alternating electric fields to resolve large genomic DNA fragments, generating unique pattern profiles for strain comparison.

Methanogens

Anaerobic organisms belonging to domain Archaea that produce methane gas as an end product of energy metabolism in strictly oxygen-free environments.

Lactic acid bacteria

A group of Gram-positive, aerotolerant or facultative anaerobes that ferment carbohydrates to produce lactic acid, essential in dairy fermentations.

Cyanobacteria

Photosynthetic prokaryotes containing chlorophyll a that perform oxygenic photosynthesis using water and light, sometimes capable of fixing atmospheric nitrogen.

Obligate aerobes

Organisms that strictly require molecular oxygen for growth and survive exclusively through aerobic cellular respiration.

Facultative anaerobes

Organisms that can grow in the presence or absence of oxygen, utilizing aerobic respiration when oxygen is present and switching to anaerobic pathways or fermentation when absent.

Enterobacteriaceae

A taxonomic family of Gram-negative, rod-shaped bacteria that are typically facultative anaerobes and include both normal intestinal microbiota and pathogens.

Coliforms

A functional group of Enterobacteriaceae defined by their ability to ferment lactose with the production of acid and gas under specified test conditions.

Endospore

A dormant, non-reproductive bacterial resting structure that exhibits extreme resistance to heat, desiccation, ultraviolet radiation, and toxic chemicals.

Hypha

A multicellular, filamentous microscopic thread that forms the basic structural unit of a mold.

Mycelium

A visible, vegetative, tangled mass or network formed by branching fungal hyphae.

Dimorphic fungi

Fungi that can grow alternately as multicellular molds or unicellular yeasts depending on environmental variables like temperature.

Mycoses

Infectious diseases in humans or other animals caused by pathogenic or opportunistic fungi.

Definitive host

The specific host organism in which a parasitic worm or protozoan reaches sexual maturity and undergoes sexual reproduction.

Intermediate host

The host organism that shelters immature, larval, or developmental non-sexual stages of a parasite.

Dead-end host

A host that can harbor a parasite and suffer disease, but from which the parasite cannot complete its life cycle or be transmitted onward.

Biological vector

An arthropod vector that actively transmits a pathogen and inside which the pathogen undergoes multiplication or required developmental changes.

Mechanical vector

An arthropod that passively transports a pathogen on its outer body surfaces without the pathogen replicating or developing internally.

biochemical typing

A method used to identify and differentiate bacterial species based on their biochemical activities, such as the utilization of specific substrates or the production of particular enzymes.

molecular typing

A method used to characterize organisms based on their molecular features, such as DNA, RNA, or protein sequences, allowing for differentiation between species or strains.

antibiograms

Reports that show the susceptibility of bacteria to various antibiotics, helping guide effective treatment options.