Prokaryotes: Bacteria and Archaea

What are the prokaryotic domains?

Prokaryotic life is divided into two domains: Archaea and Bacteria. Their respective kingdoms are Eubacteria and Archaebacteria.

The third domain, Eukarya, contains all eukaryotic organisms.

Gram stain

Traditional methods of species identification don’t apply to prokaryotes that reproduce primarily asexually.

One of these techniques used to identify asexual prokaryotes is the ______.

This divides bacteria into two major groups.

This technique isn’t useful for archaea due to their various cell wall structures

Gram positive

have cell walls with a thick protein layer, lack an outer membrane, and stain purple.

• staphylococcus

• streptococcus

Gram negative

have cell walls with a thin protein layer, have an outer membrane, and stain pink. These bacteria are more resistant to antibiotics

• Enterobacterias

• Chlamydia

Other ways to classify prokaryotes:

Size, shape, nutrition, movement, habitat, and genetics

Structure of Bacteria and Archaea

Coccus, Bacillus, Spiral

Other shapes of bacteria

Pyramids, prisms, and flexible with star-shaped cross-sections.

Other shapes of archaea

Can be shaped as platelike, rectangular prisms or have a flexible form.

How does archaea acquire nutrition?

They obtain energy via methanogenesis; a process where methane is produced as a by-product of carbon breakdown.

Some archaea have species that are heterotrophs (consumers)

How does bacteria acquire nutrition?

Some are heterotrophs

Some bacteria can perform photosynthesis

Where does bacteria live?

Bacteria live in a range of aerobic and anaerobic (no oxygen containing) environments. Common habitats: guts of animals, swamp sediments and landfills.

• Bacteria are generally mesophiles, meaning that they live in moderate conditions

Where does archaea live?

Archaea live in a range of aerobic and anaerobic (no oxygen containing) environments. Common habitats: guts of animals, swamp sediments and landfills.

• Archaea include several species considered to be extremophiles, meaning that they live in extreme conditions (extreme temperatures, pH, salinity, and etc)

How does Bacteria and Archaea move?

Via the structures flagellum (flagella) and pilus (pili)

Flagella is a whip like structure and the number of it is useful in classification

Pili are short hair-like structures that aid in movement and attaching to surfaces.

How do archaea and bacteria reproduce?

Lacking a nucleus denies prokaryotes mitosis, so they undergo binary fission.

In this process, a single cell is split and a wall known as a septum is created.

Under ideal conditions, prokaryotes divide every 20 minutes.

Conjugation

Prokaryotic cells transferring genetic material from one organism to another.

The DNA transferred is a plasmit. A plasmid is a piece of DNA that can split from the chromosome and exist as a separate loop.

How does natural selection create antibiotic resistance?

In a population of bacteria, there will always be genetic variation present. Some bacteria will be more susceptible to antibiotics and some less.

Those with anti-biotic resistant traits will have a higher chance of survival, thus reproducing, and passing on those beneficial traits.

Eventually, it will create a population that is stronger and resistant to antibiotics.

Finishing your course of antibiotics prevents resistant strains from forming, creating stronger resistance, and spreading.

How do Bacteria and Archaea influence other life?

Bacteria performing normal life functions can result in food spoilage, illness, and decomposition

Nutrient cycles rely on bacteria to breakdown nitrogen, carbon, and sulfur, making it available for other organisms.