Microbes are very easy and very difficult to study
Bacteria and archaea are predominantly single-celled, while eukaryotes can be single-celled or highly complex multicellular organisms
Microbes are ubiquitous and found deep in the earth’s crust, in polar ice caps and oceans, inside the bodies of plants and animals, and in the earth’s landscape
Microorganisms are the main forces that drive the structure and content of the soil, water, and atmosphere
Historical uses of microbes by humans include bread, alcohol, and cheese production, treatment of wounds, mining precious metals, and cleaning up contamination
Genetic engineering manipulates the genetics of microbes, plants, and animals to create new products and GMOs
The vast majority of microorganisms that associate with humans are harmless or beneficial, but pathogens can cause disease
Emerging and reemerging diseases include AIDS, Hepatitis C, Zika virus, West Nile virus, and Tuberculosis
Increasing number of patients with weakened defenses are subject to infections by common microbes and an increase in drug-resistant microbes
Eukaryotes contain organelles and are larger than bacteria and archaea, which lack organelles
Viruses are not independently living cellular organisms and are composed of hereditary material surrounded by a protein coat
Polysaccharides contribute to structural support and protection, serve as nutrient and energy stores
Cells can be spherical, polygonal, cuboidal, or cylindrical, contain protoplasm encased in a cell membrane, have chromosomes containing DNA, and ribosomes for protein synthesis
Taxonomy is the science of classifying living things, nomenclature assigns scientific names, classification arranges organisms into a hierarchy, and identification discovers and records traits of organisms
The binomial system of nomenclature combines genus and species names, and scientific names are italicized in print and underlined by hand
Classification ranks organisms from Domain to Species
Phylogeny represents the natural relatedness between groups of living beings, and evolution involves hereditary information gradually changing through time
COVID-19 evolved to infect humans from non-human animals due to small changes in genetic information
An entirely new system of taxonomy based on domains includes Bacteria, Archaea, and Eukarya
Bacteria with thicker walls are more resistant to antibiotics that target the cell wall.
Some bacteria can be classified as "intermediate" because they do not fit neatly into either category.
Gram-positive bacteria have a thick peptidoglycan layer in their cell wall, while gram-negative bacteria have an outer membrane containing lipopolysaccharides.
Gram staining is used to differentiate bacteria into two major categories (gram positive or gram negative) based on their ability to retain crystal violet dye during the staining process.
Peptidoglycan consists of alternating sugars (N-acetylglucosamine and N-acetylluramic acid) crosslinked by short polypeptide chains.
The cell wall is composed of peptidoglycan, which provides strength to the bacterial cell.
The domain Eukarya contains all eukaryotic cells, including protists, fungi, plants, and animals.
Prokaryotes have no nucleus or other membrane-bound organelles, while eukaryotes have these structures.