Bacteria, Archaea, and Viruses

Domains

• Bacteria   * Archaea   * Eukarya

Eukaryotes

• Possibly multicelled   * Nucleus   * Branch off of archaea   * Membrane-bound organelles

Endosymbiosis theory

• Cyanobacteria   * chloroplasts   * Protobacteria     * mitochondria   * Phospholipid bi-layer   *

Protists

• Eukaryotes that are not plants, animals, or fungi   * Acquiring organelles     * Flexible cell surface that allows them to have infoldings     * These folds make cell compartments, these compartments have specialization   * Organelles are double membraned because when they entered the protist they took some of the cell wall with them.     * Mitochondria, used to detoxify O2     * cyanobacterium enters a cell, chloroplast has two membranes     * Eukaryote engulfs a green algae cell       * Green algae cell becomes a chloroplast, has three membranes   * Nuclear envelope - membrane infoldings   * Cytoskeleton - cytoplasmic microtubules

Prokaryotes

• Single celled   * DNA is in a ring     * Plasmids add DNA   * No mitosis     * Binary fission   * Cell wall, not cell membrane   * No nucleus   * No organelles   * Bacteria are prokaryotes   * Important decomposers

Nitrogen cycle

• Nitrogen fixers   * Convert atmospheric N2 to ammonia   * Air to ground   * Nitrifiers     * Ammonia to nitrate     * Soil to soil     * Nitrogen is now consumable by plants   * Denitrifiers     * Nitrate to N2     * Soil to air   *
• Both   * Ribosomes   * Cell wall   * Metabolic pathways     * Respiration     * Photosynthesis   * ATP

Archaea

• Extremophiles   * rRNA allows you to differentiate between Archaea and Bacteria   * Common in soil or the ocean   * Prokaryotic   * No peptidoglycan   * Lipid monolayer   * Some are obligate anaerobes

Bacteria

Lateral Gene Transfer

• Bacteria transfer plasmids through “bridges” which donates genetic material to another bacteria   * Plasmids are the smallest stretch of DNA   * Have the ability to target the nucleus and alter DNA, GMO   * Bacteria from environment   * Common for antibiotic resistance   * Makes it difficult to interpret genome analysis

Bacterial Cell Wall

• Peptidoglycan   * Takes the place of cellulose   * Gram positive     * Thick outside layer of peptidoglycan     * Stains purple, blue stain bonds to PepGly   * Gram negative     * Cell envelope, thin peptidoglycan in a phospholipid bilayer sandwich     * Stains pink, stain does not bond

Shapes

• Coccus   * Sphere   * Cock and balls   * Bacillus     * Rod     * Back should be straight rod   * Spirillum     * Spiral   * Bacillus and Spirillum can form chains/clusters     * Chains form during division when cells fail to separate   * Branched filaments     * Produce spores in order to reproduce

Endospores

• Nutrients scarce? Simply pack your genetic material into a cell wall package and wait for that package to be rehydrated!   * Rest of the cell dies   * Food poisoning

Cyanobacteria

• Single-celled, form colonies   * Photosynthetic   * Fix nitrogen     * heterocyst   * Big oxygen producers   * Photosynthetic lamellae     * Those little indents in the cell wall that allow for photosynthesis to take place     * Works in place of a chloroplast   * Origin of chloroplasts in Eukaryotes

Spirochaeta

• Internal flagella that allows them to move around   * Syphilis, Lyme   * Chlamydia     * Obligate parasite     * STDs, pneumonia

Protobacteria

• Where the mitochondria was derived from   * Largest group of bacteria   * Nitrogen fixers     * Rhizobium, legumes   * Escherichai coli

Biofilms

• Sticky polysaccharide matrix   * Makes cells harder to kill, antibiotic resistance, environmental resistance   * Dental plaque   * Bacteria binds to a surface, a larger colony forms, the bacterial matrix forms

Quorum sensing

• Sending chemicals and establishing communication with other bacteria   * Attracts more bacteria to the biofilm area

Human Microbiomes

• Important to our health   * Antibiotics deplete them

Endotoxins

• Lyse: bacterial puncture/death   * Rarely fatal   * Salmonella

Exotoxins

• Released by living bacteria, continual proliferation   * Highly toxic, often fatal   * Black plague

Extremophiles

• Prokaryotic   * Bacteria and archaea   * Thrive under extreme conditions   * Radiation, temperature, pH, salinity, heavy metals   * Thermostable proteins that prevent denaturing   * Not as abundant

Metabolic pathways

• Obligate anaerobes   * Oxygen is poisonous   * Those homies that live inside termites   * Relic of prehistoric life   * Facultative anaerobes     * Both aerobic and anaerobic pathways   * Obligate aerobes     * Require oxygen   * Photoautotrophs     * Produce their energy from the sun, photosynthesise     * Use CO2   * Photoheterotrophs     * Use the sun for energy but have to consume organic material in order to get carbon   * Chemoautotrophs     * Get energy from inorganic compounds     * Use CO2 for carbon   * Chemoheterotrophs     * Get energy from organic compounds as well as their carbon     * Humans

Viruses

• Infectious particles   * Obligate parasites     * Need a host to survive   * DNA or RNA     * This is not typical   * Infect all forms of life   * Grouped based on genome structure     * Hard to classify based on physiological differences

What makes up a virus?

• Genetic material: RNA or DNA   * A viral capsid     * Protein around genetic material   * Some have a membrane envelope and spike proteins     * Similar to cell membrane     * Virus can leave cell and steal membrane

Negative-sense

• Has negative-sense RNA that is not ready to be translated   * Uses the host cell to create positive-sense RNA   * RNA polymerase helps it convert from negative to positive

Positive-sense

• RNA ready to be translated   * Doesn't need to bring its own RNA polymerase     * Host already has it   * Most abundant and diverse group     * Covid     * Mosaic viruses       * Just genetic material and capsid

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