Lecture 3.1

Prokaryotes

Unicellular organisms with no internal organelles and circular DNA.

Asexual Reproduction

A type of reproduction where one cell divides into two identical cells.

Halobacterium

A type of prokaryote that survives in high salt concentrations by pumping potassium ions.

Osmotic Pressure

The pressure exerted by the flow of water through a semi-permeable membrane due to solute concentration differences.

Peptidoglycan

A structural component of bacterial cell walls made of sugars and polypeptides.

Gram Positive Bacteria

Bacteria with a thick peptidoglycan cell wall that retains crystal violet dye during staining.

Gram Negative Bacteria

Bacteria with a thin peptidoglycan layer sandwiched between two membranes, which do not retain crystal violet dye.

Nutritional Modes of Prokaryotes

Diverse ways in which prokaryotes obtain energy and carbon, including photoautotrophs and chemoheterotrophs.

Nitrogen Fixation

The process by which some prokaryotes convert atmospheric nitrogen into ammonia.

Endospore

A dormant, resistant structure formed by some bacteria under harsh conditions, protecting their genetic material.

Facultative Anaerobes

Organisms that can utilize oxygen if available, but can also survive without it.

Extremophiles

Prokaryotes that thrive in extreme environments, such as high salinity or extreme temperatures.

Endosymbiotic Theory

The theory suggesting that eukaryotic cells evolved through symbiotic relationships between different species.

Antibiotic Resistance

The ability of bacteria to survive and reproduce despite the presence of antibiotics.

Microbiome

The ecosystem of bacteria living in the human gut, important for digestion and health.

Binary Fission

A form of asexual reproduction in which a prokaryote cell divides into two identical daughter cells.

F plasmid

A plasmid that allows for the transfer of genetic material between prokaryotes during conjugation.

Chemoautotrophs

Organisms that obtain their energy from chemical sources rather than sunlight.

Bio-remediation

The use of prokaryotes to break down and remove pollutants from the environment.

E. coli

A type of bacteria commonly used in genetic research due to its simple structure and ease of culture.

Prokaryotes

Unicellular organisms that lack internal organelles and are characterized by their simple structure.

Binary fission

A form of asexual reproduction in prokaryotes where a single cell divides into two identical daughter cells.

Halobacterium

An archaean prokaryote that survives in hyper-saline environments and pumps potassium ions to balance osmotic pressure.

Peptidoglycan

A large polymer that forms the cell wall of bacteria, composed of sugars and amino acids.

Gram-positive bacteria

Bacteria that have a thick peptidoglycan layer and stain purple during Gram staining.

Gram-negative bacteria

Bacteria that have a thin peptidoglycan layer and an outer membrane, staining pink during Gram staining.

Capsule

A sticky layer of polysaccharides or proteins surrounding the cell wall of some prokaryotes, aiding in adhesion.

Endospore

A highly resistant structure formed by some bacteria in response to harsh conditions, allowing survival for extended periods.

Conjugation

The process by which genetic material is transferred between prokaryotic cells through direct contact.

Antibiotic resistance

The ability of bacteria to survive and grow in the presence of antibiotics, often due to genetic mutations and selection.

Nitrogen fixation

The process by which some prokaryotes convert atmospheric nitrogen (N2) into ammonia (NH3), making it usable for plants.

Chemoheterotrophs

Organisms that obtain their energy and carbon by consuming organic compounds from other organisms.

Facultative aerobes

Prokaryotes that can survive in both aerobic and anaerobic environments.

Extremophiles

Prokaryotes that thrive in extreme environmental conditions, such as high temperatures or salinity.

Microbiome

A community of microorganisms, including bacteria, that inhabit a specific environment, such as the human gut.

Prokaryotic phylogeny

The evolutionary history and relationships among the different groups of prokaryotes.

Why do lakes turn pink?

Very high salt concentration

Most prokaryotes are

• Unicellular

• Have no internal organelles

• Have many shapes

• Small

Common prokaryotes shapes

• Spherical

• Rod-shaped

• Spiral

Prokaryotes cell wall

Provides protection against osmosis stress

Bacterial cell walls contain

Peptidoglycan

What do some prokaryotes cell wall have

Some have naked cell walls, others have an additional cell membrane on top of the cell wall

What is the cell wall surrounded by in many prokaryotes

Capsule

Capsule

In many prokaryotes, the cell wall is surrounded by a sticky layer of polysaccharide or protein

Fimbriae

Hairlike appendages in some prokaryotes cell wall

Prokaryotes structural adaptations

Endospore, flagellum

Endospore

Highly protective, multilayer coat forms around the chromosome, water removed, metabolism stops

How is the endospore formed?

When faced with harsh conditions

Name

Endospore

Flagellum

Allows prokaryotes to move

Name

Flagellum

Genetic diversity in prokaryotes main factors

Rapid reproduction, mutation and genetic recombination

Name

Conjugation and recombination

Obligate aerobes must…

Use O2 for cellular respiration

Obligate anerobes are…

Poisoned by O2, and either use another terminal electron acceptor or only conduct fermentation

Facultative aerobes

Very flexible and can work in either aerobic or anaerobic environments

What is nitrogen essential for?

The production of amino acids and nucleic acids in all organisms

Nitrogen fixation

Some prokaryotes incorporating N2 from atmosphere into ammonia

Five clades based on molecular data

Proteobacteria, chlamydias, spirochetes, cyanobacteria, gram-positive bacteria

Proteobacteria

Very diverse clade including nitrogen fixing bacteria

Chlamydias

Parasitic bacteria, survive only in animal cells, depend on host for resources as basic as ATP

Spirochetes

Spiral, most free-living, some pathogenic parasites

Cyanobacteria

Only prokaryotes with plant-like oxygen-generating photpsynthesis

Gram-positive bacteria

Very diverse clade, include streptomyces

Archaea

Share traits with bacteria and eukarya and some are unique

Archaea include

Extremophiles, methanogens

Extremophiles

Grow in extreme salt or temperature environments

Methanogens

Decomposers

Chemical recycling

The process by which essential elements are reused in the ecosystem, typically involving decomposition and transformation of organic materials by microorganisms.

Ecological relationships parts

Mutualist, commensal, parasitic

How prokaryotes affect humans?

• Mutualistic bacteria (+/+)

  • Pathogenic bacteria