BISC 120 - Lecture 18: Prokaryotes and Virus Wrap-Up

Comprehensive vocabulary flashcard deck covering virus wrap-up concepts, prion diseases, prokaryote characteristics, metabolic modes, cellular morphology, genetic mechanisms, and antibiotic resistance from Lecture 18.

HIV

Human Immunodeficiency Virus; an enveloped retrovirus that attacks white blood cells and can cause AIDS.

Retrovirus

An RNA virus that forms a DNA provirus inside the host cell.

HIV genome pathway

Viral RNA $\rightarrow$ DNA provirus in the host cell.

Coronavirus

Enveloped, single-stranded RNA virus with spike glycoproteins forming a crown-like corona.

Coronavirus spikes

Glycoproteins that attach primarily to animal mucus-membrane cells.

SARS

Severe acute respiratory syndrome caused by certain coronavirus strains.

2019 - SARS-CoV-2

SARS-CoV-2 was first identified in 2019 and causes COVID-19.

Pandemic

An epidemic caused by one disease strain that spreads around the world.

Antibiotics and viruses

Antibiotics do not work on viruses.

Antiviral drugs

Can interfere with viral binding to cells or with viral replication inside cells.

Vaccines

Harmless viral derivatives can stimulate a specific immune response against a virus.

1977 - smallpox

The lecture notes that smallpox was last diagnosed in 1977.

Prion

A misfolded protein that induces normal proteins to misfold, causing a chain reaction and disease.

Kuru

Prion disease associated with cannibalism in Papua New Guinea.

BSE

Bovine spongiform encephalopathy, or mad cow disease; a prion disease.

Prokaryotes

Cells lacking a membrane-enclosed nucleus and membrane-enclosed organelles.

Domains containing prokaryotes

Bacteria and Archaea.

Prokaryotes as a group

Paraphyletic rather than a single monophyletic clade.

Prokaryotic ecological diversity

Prokaryotes occupy many niches as autotrophs, decomposers, parasites, extremophiles, and symbionts.

Photoautotroph

Uses light for energy and $CO_2$ as its carbon source; cyanobacteria are an example.

Chemoautotroph

Uses chemical energy and $CO_2$ as its carbon source.

Chemoautotroph examples

Sulfolobus can use sulfides; some bacteria use ammonia for energy.

Heterotroph

Uses organic compounds as its carbon source.

Photoheterotroph

Uses light for energy but organic compounds as its carbon source; Chloroflexus is an example.

Chemoheterotroph

Uses organic compounds for both energy and carbon; common in many bacteria.

Chemoheterotroph examples

E. coli and Streptococcus are lecture examples.

Coccus

Spherical bacterial shape; Streptococcus and Staphylococcus are examples.

Bacillus

Rod-shaped bacterium; E. coli and Bacillus anthracis are examples.

Spirochaete

Spiral-shaped bacterium; Treponema pallidum is the lecture example.

Treponema pallidum

Spirochaete bacterium that causes syphilis.

Prokaryotic chromosome

Most bacterial genes are on a single, usually circular chromosome.

Nucleoid

Non-membrane-bound region where the tightly coiled prokaryotic chromosome is located.

Plasmid

Small extra-chromosomal circular DNA molecule that replicates independently.

Bacterial cell wall

Usually lies outside the plasma membrane and contains peptidoglycan.

Peptidoglycan

Sugar-polypeptide polymer that is an important component of bacterial cell walls.

Archaeal cell wall

Contains polysaccharides and proteins but lacks peptidoglycan.

Gram stain

Method used to classify bacteria by differences in cell wall composition.

Gram-positive bacteria

Have simpler walls with a large amount of peptidoglycan.

Gram-negative bacteria

Have less peptidoglycan plus a more complex outer membrane.

Gram-negative antibiotic resistance

Often more resistant because their outer membrane adds a protective barrier.

Capsule

Sticky polysaccharide or protein layer outside the cell wall in many prokaryotes.

Capsule functions

Helps attachment/biofilms, prevents desiccation, and can protect pathogens from host defenses.

Biofilm

Community of cells attached to a surface, often aided by a sticky capsule.

Bacterial flagellum

Movement structure made of a motor, hook, and filament.

Flagellar power source

A proton gradient across the cell membrane powers bacterial flagellar movement.

Plasmid antibiotic-resistance genes

Some plasmids carry genes that provide antibiotic resistance.

Binary fission

Asexual cell division used by prokaryotes; daughter cells are generally identical.

Prokaryotic reproduction rate

Often every 1-3 hours, and sometimes as fast as about every 20 minutes.

Mutation and rapid reproduction

Low mutation rates can still produce many mutations because prokaryotes reproduce so quickly.

Horizontal gene transfer

Movement of genetic material between cells rather than only from parent to offspring.

Transformation

Uptake and incorporation of foreign DNA from the environment, often from dead cells.

Transduction

Transfer of genes through bacteriophages or viral DNA.

Conjugation

Direct one-way transfer of genetic material between prokaryotic cells.

Pilus

Structure that attaches a donor cell to a recipient during conjugation.

F factor

DNA element containing genes required for pilus production and conjugation.

F+ cell

Cell containing the F factor; functions as a DNA donor during conjugation.

F- cell

Recipient cell lacking the F factor before conjugation.

F factor transfer

Transfer of the F factor can convert an F- recipient into an F+ donor.

DNA transferred in conjugation

Usually plasmid DNA, although chromosomal DNA can also be transferred.

Antibiotic resistance evolution

Rapid reproduction, mutation, and horizontal gene transfer can quickly produce resistant strains.

Approximate mutation rate

Lecture gives about 1 mutation per 10,000,000 per gene.

Antibiotic misuse

Not finishing treatment or inappropriate/excessive use can worsen antibiotic resistance.

Transformation vs. transduction vs. conjugation

Transformation = environment; transduction = phage; conjugation = direct cell-to-cell transfer.

Lecture 18 date/event tracker

1977: last diagnosed smallpox case; 2019: SARS-CoV-2 first identified.