A Survey of the Microbial World Part II

These flashcards provide essential vocabulary and definitions from the Microbial World Part II lecture notes, covering genetic expression, bacterial classification, eukaryotic diversity, and acellular pathogens.

DNA Replication

The process of producing two identical replicas of DNA from one original DNA molecule, occurring in all living organisms as the most essential part for biological inheritance.

Transcription

The process of making an RNA copy of a gene’s DNA sequence; this copy, called messenger RNA (mRNA), carries the encoded genes to a ribosome.

Translation

The process in which ribosomes in the cytoplasm or endoplasmic reticulum synthesize proteins from the mRNA transcript for the ultimate goal of gene expression.

Prokaryotic Ribosome

A $70\,S$ structure involved in translation, featuring the Shine-Dalgarno sequence and utilizing AUG fMethionine as the start codon.

Eukaryotic Ribosome

An $80\,S$ structure involved in translation, featuring the Kozak sequence and utilizing AUG Methionine as the start codon.

-10 Element

A specific sequence in the prokaryotic promoter region ($TATAAT$) responsible for initiation.

-35 Element

A specific sequence in the prokaryotic promoter region ($TTGACA$) responsible for binding.

TATA Box

A eukaryotic promoter region sequence located at $-35$ to $-25$ designated for binding.

Point Mutation

A type of gene mutation involving changes at specific points in the DNA, classified as Silent, Missense, or Nonsense.

Frameshift Mutation

A chromosomal mutation resulting from insertions or deletions that shifts the reading frame of the genetic message.

Prokaryotes

Microscopic single-celled organisms classified into the two evolutionarily distinct domains, Bacteria and Archaea, found in nearly every environment on Earth.

Deinococcus radiodurans

Known as "Conan the Bacterium," this genus of deeply branching bacteria is characterized as a polyextremophile.

Phylum Tenericutes

A group of atypical bacteria that are obligate parasites with no cell wall (pleomorphic), such as Mycoplasma pneumoniae.

Chlamydia trachomatis

A coccus-shaped obligate intracellular parasite that is the most common bacterial STI and lacks peptidoglycan.

Gram-Positive Bacteria

Bacteria characterized by a thick peptidoglycan cell wall with $+40$ layers ($20-80\,nm$), containing teichoic acid and staining purple.

Gram-Negative Bacteria

Bacteria characterized by a thin peptidoglycan cell wall ($3$ layers, $8-11\,nm$) between inner and outer membranes; the outer membrane contains lipopolysaccharides (LPS) and stains pink.

Phylum Cyanobacteria

Unicellular or filamentous photosynthetic bacteria, commonly known as Blue-Green "Algae," that produce ~$20-30\%$ of global oxygen.

Phylum Spirochaetes

Long, thin, and helical bacteria characterized by axial filaments for efficient movement through viscous liquids and tissues.

Archaea

A domain of highly diverse prokaryotes and masters of extreme environments (extremophiles), such as high salt, extreme pH ($pH < 0$), and hydrothermal vents ($+400^{\circ}C$).

Protist

A diverse catch-all group of eukaryotic microorganisms that can be pathogenic, photosynthetic, saprophytic, or free-living.

Protozoa

A large and diverse group of unicellular chemoheterotrophic eukaryotes that are classified primarily by their movement type.

Naegleria fowleri

Known as the "Brain Eating Amoeba," this member of SubGroup Heterolobosea causes primary amebic meningoencephalitis (PAM).

Lichen

Unique organisms resulting from a symbiotic relationship between a fungus (Ascomycota or Basidiomycota) and a photosynthetic partner (Green Algae or Cyanobacterium).

Fungi

Heterotrophic, saprozoic eukaryotes split into unicellular yeast and multicellular mushrooms or molds, possessing chitin cell walls and ergosterol cell membranes.

Microsporidia

Unicellular, non-motile obligate intracellular parasites that lack hyphae and ergosterol, and are considered the smallest known Eukaryotes.

Helminths

Large multicellular organisms that are usually parasitic with complex life cycles; major groups include Platyhelminthes (Flatworms) and Nematodes (Roundworms).

Enterobius vermicularis

Commonly known as Pinworm, it is the most common parasitic worm in the USA; gravid females migrate to the perianal region at night to lay eggs.

Schistosoma spp.

Also known as Blood Flukes, these parasites have a life cycle where free-swimming larvae (cercariae) penetrate human skin in freshwater.

Virus

Obligate intracellular parasites consisting of DNA or RNA genomes that rely on host machinery for metabolism and reproduction.

Viroids

Short, circular $ssRNA$ molecules that self-replicate without a protein coat by hijacking host machinery; primarily cause plant diseases.

Prion

A misfolded protein ($200-250$ amino acids) rich in beta-sheets that can transmit its shape to normal variants, causing fatal neurodegenerative diseases like Bovine Spongiform Encephalopathy.