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