Microbiology in Biomedical Science – Vocabulary Review

Vocabulary flashcards covering essential microbiology and biotechnology terms from the lecture, aiding exam preparation.

Prokaryote

A unicellular organism (Bacteria or Archaea) lacking a membrane-bound nucleus and membrane-bound organelles.

Eukaryote

An organism whose cells possess a true membrane-enclosed nucleus; includes micro-eukaryotes such as protists, fungi, and parasites.

Bacteria

Domain of prokaryotic microorganisms characterized by ester-linked membranes, 70S ribosomes, and peptidoglycan cell walls containing muramic acid.

Archaea

Domain of prokaryotes with ether-linked membrane lipids and 70S ribosomes but lacking muramic acid; no known pathogenic species.

LUCA (Last Universal Common Ancestor)

The hypothetical ancestral cell from which all current cellular life—Bacteria, Archaea, and Eukarya—evolved.

Binary Fission

A form of asexual reproduction in prokaryotes where one cell divides into two genetically identical daughter cells.

Semi-Conservative DNA Replication

Replication mechanism where each new DNA molecule contains one original strand and one newly synthesized strand.

Central Dogma

The flow of genetic information: DNA → RNA → Protein, governing gene expression and phenotype.

70S Ribosome

Smaller ribosome found in Bacteria and Archaea, composed of 50S and 30S subunits.

80S Ribosome

Larger ribosome of eukaryotic cells, composed of 60S and 40S subunits.

Ester Linkage

Chemical bond joining fatty acids to glycerol in bacterial and eukaryotic membrane lipids.

Ether Linkage

Bond connecting isoprenoid chains to glycerol in archaeal membrane lipids, conferring heat and chemical resistance.

Plasmid

Small, autonomously replicating DNA molecule in bacteria that typically carries accessory (non-essential) genes.

Bacterial Chromosome

Main circular DNA molecule in bacteria containing essential genes for survival and reproduction.

Extremophile

Microorganism able to thrive in extreme environments such as high temperature, high salinity, or low pH.

Pathogen

A microorganism (bacterium, virus, or micro-eukaryote) capable of causing disease in a host.

Virulence Factor

Molecule or structure that enhances a pathogen’s ability to infect, cause damage, or evade the host immune response.

Pili

Hair-like surface appendages of bacteria used for adhesion, conjugation, or motility.

Biofilm

Structured microbial community attached to a surface and embedded in a self-produced extracellular matrix.

Spore

Dormant, highly resistant cell form produced by certain bacteria to survive unfavorable conditions.

Capsule

Thick, gelatinous layer outside some bacterial cell walls that aids in evasion of host defenses.

Quorum Sensing

Cell-to-cell communication mechanism in bacteria that detects population density and regulates gene expression accordingly.

Growth Curve

Graph depicting microbial growth phases in a closed system: lag, exponential, stationary, death, and long-term stationary.

Minimal Medium

Culture medium containing only essential nutrients that allow a microorganism such as E. coli to synthesize all macromolecules from a single carbon source.

Taq DNA Polymerase

Heat-stable DNA polymerase from Thermus aquaticus used to synthesize DNA during PCR.

Thermus aquaticus

Thermophilic bacterium isolated from hot springs; source organism of Taq DNA polymerase.

PCR (Polymerase Chain Reaction)

Technique that amplifies specific DNA sequences through repeated cycles of denaturation, annealing, and extension using a thermostable polymerase.

Processivity

Measure of how many nucleotides a DNA polymerase can add to a growing strand before dissociating from the template.

Fidelity

Accuracy with which a DNA polymerase incorporates the correct nucleotide during DNA synthesis.

T4 DNA Ligase

ATP-dependent enzyme from bacteriophage T4 that joins DNA fragments by forming phosphodiester bonds; widely used in cloning.

Blunt-End Ligation

Joining of two DNA fragments with flush-ended termini by DNA ligase.

Sticky-End Ligation

Joining of DNA fragments possessing complementary single-stranded overhangs facilitated by DNA ligase.

Chemolithotrophy

Metabolic strategy where organisms obtain energy by oxidizing inorganic molecules (e.g., NH3, H2S).

Koch’s Postulates

Four criteria establishing a causative relationship between a microbe and a disease, developed by Robert Koch.

Operon

Cluster of functionally related genes transcribed as a single mRNA and controlled by a shared regulatory region.

Transformation (Griffith)

Uptake of free DNA by bacteria resulting in a genetic change, first demonstrated in Pneumococcus.

Conjugation

Horizontal gene transfer process where DNA is exchanged between bacteria via direct cell-to-cell contact.

Restriction Enzyme

Bacterial endonuclease that cuts DNA at specific sequences; foundational tool for molecular cloning.

DNA Ligase Fusion Protein

Engineered chimera combining T4 DNA ligase with a DNA-binding domain to enhance ligation efficiency for applications like NGS adapter ligation.