Ch 26 Bacteria and Archaea (Prokaryotes)

What are prokaryotes?

Organisms that do not have a membrane bound nucleus

True or False: Most Prokaryotes are unicellular

True

What are the 2 main domains of prokaryotes?

Archaea and bacteria

Fill on the Blank: Archaea and Bacteria lack a _______ _____ but both have a _______ ______

Nuclear Envelope

Plasma Membrane

What is microbiology?

The study of organisms that can be seen only w/ the aid of a microscope

Fill in the Blank: Some Prokaryotes thrive in extreme environments; they are known as _______

Extremophiles – bacteria or archaea that live in high-salt, high-temp/low-temp, or high-pressure habitats 

True or False: We can’t find much information on prokaryotes to help us understand the past.

False: Studying them have been helpful for understanding the tree of life, developing industrial applications, and exploring the structure and function of enzymes 

What are the ways that studying prokaryotes have helped us?

• Origin of Life – the first forms of life prolly lived in extreme conditions so it could help explain the beginning of life 

• Extraterrestrial life – if other prokaryotic cells can thrive in extreme habitats 

• Commercial Applications – bc enzymes that function at extreme temps and pressures are useful in many industrial processes, they are of commercial interest 

• Medical Importance - Thousands of bacteria species live in and on the body, but only a small faction can disrupt the body’s function enough to cause illness 

What are pathogens?

Bacteria that cause disease

How do we characterize prokaryote diversity?

• Genetic, physiological, morphological, molecular characteristics

Fill in the Blank: Bacteria can be shaped like ____ (bacilli), _____ (Cocci), and______ (helical)

Rods

Spirals

Helical

Bacteria can swim, but how? Bacteria can glide, but how?

Bacteria can swim with rotating flagella

Bacteria can glide, but we don’t know how yet

In what ways can we test prokaryote diversity?

• Enrichment Culture - a method of detecting and obtaining cells w/ specific characteristics by placing a sample, containing many types of cells under a specific set of conditions and isolating those cells that grow rapidly in response

• Metagenomics - method to catalog all the genes present in a mixed community of prokaryotes by extracting and sequencing DNA from an environmental sample that contains numerous unknown species 

• Direct Sequencing - a technique based on isolating and sequencing a specific gene from organisms found in a particular habitat 

What is bioinformatics?

A discipline concerned w/ the storage, analysis, and presentation of biological data

In what ways can we find the differences between Bacteria and Archaea?

Cell membranes, cell walls, metabolic diversity, genetic machinery for making proteins

Bacteria and Archaea have different plasma membranes but why?

• Bacteria - plasma membranes that contain phospholipids w/ ester bonds

• Archaea - plasma membranes that have unique lipids that cotain ether bonds

True or False: Ether bonds in Archaea are more stable which allows it to survive in extreme conditions

True

What are the differences in cell wall of Bacteria and Archaea?

Bacteria - presence of peptidoglycans

Archaea - no peptidoglycans, but still cell walls

True or False: The presence of peptidoglycans affects the response to external environements

True

What is a grain stain?

how biologists distinguish bacteria using a dyeing system that relies on the presence of peptidoglycan in the cell walls

What are the two types of results that come from a grain stain?

• Gram-Positive (purple) – cells that have a plasma membrane surrounded by a cell wall w/ extensive peptidoglycan 

• Gram-negative (pink) – have a plasma membrane surrounded by a cell wall that has two components a thin layer containing peptidoglycan and an outer phospholipid layer 

How can we use genetic machinery for making proteins to differentiate between archaea and bacteria?

• RNA Polymerase - Archaea have a single type w/ 13 subunits, bacteria have a simpler type w/ only 5 subunits

• First Amino Acid in Translation during protein synthesis - Bacteria starts w/ formyimethionie and archaea starts w/ methionione

• Histones - Archaea have histones associated w/ their DNA but bacteria do not

Why is protein important?

Protein leads to potential growth and reproduction

Why are bacteria and archaea masters of metabolism?

Bc they can subsist on almost anything

How do both domains acquire energy to produce ATP in 3 ways?

• Phototrophs “light feeders” - use light energy to excite electrons so ATP is produced by photophosphorylation 

• Chemoorganotrophs “chemical-carbon-feeders" - oxidize organic molecules w/ high potential energy like sugars, and ATP may be produced by cellular respiration w/ sugars serving as electron donors or via fermentation pathways 

• Chemolithotrophs “chemical-rock-feeders" - oxidize inorganic molecules w/ high potential energy, so ATP is produced by cellular respiration and inorganic compounds serve as the electron donor 

What are the 2 ways do bacteria and archaea obtain building-block compounds?

• Autotrophs “self-feeders” - synthesize their own compounds from simple starting materials such as carbon dioxide and methane 

• Heterotrophs “other-feeders” - absorb ready-to-use organic compounds (building-block compounds) produced by other organisms in their environment 

True or False: Lateral gene transfer is central to the evolution of bacteria and archaea bc prokaryotes can acquire diverse traits

True

What is the process of lateral gene transfer in bacteria and archea?

• Transformation – when bacteria or archaea naturally take up DNA from the environment that has been released by cell lysis or secreted 

• Transduction – when viruses pick up DNA from one prokaryotic cell and transfer it to another cell 

• Conjugation – when genetic info is transferred by direct cell-to-cell contact 

How can conjugation happen?

• Plasmid – a small circular piece of DNA that is copied in once cell and transferred to the other cell 

• Can result in genetic recombination when a plasmid that has become integrated into the main bacterial chromosome is copied and transferred, along w/ the genes from the main bacterial chromosome, to a recipient cell 

True or Fals: Sexual reproduction happens in prokaryotes

False; it doesn’t happen bc they are haploid throughout their lives

True or false: Genes can move from one individual to another via conjugation

True

What is true about Archaea?

• No pathogens/parasites

• Some are symbiont (mutualistic +/+ relationship)

• Primarily Exdtremeophiles

What are teh 4 types of Archaea?

Thermophiles

Acidophiles

Halophiles

Methanogens

Archaea: What are thermophiles and their conditions?

• Live in extremely high temps (140 – 175 degrees farenheight or 60 to 80 degrees celsius) 

• Ex: Hot springs, geysers, hydrothermal vents (oceanic) 

• Heat stable enzymes allow for organisms to have normal metabolism/growth/and reproduction in high temps 

Archaea Types: Acidophiles

• Live in extremely low pH (Acidic; pH less than 2) 

• Naturally acid environments like pine forests, bogs, not natural but still acid mine drainage (AMD) 

• Food: Sour cream, yogurt, buttermilk 

Archaea Types: Halophiles

• Live in extremely high salinity  

• 35-40% of salinity 

• Natural Saline Habitats – great salt lake, dead sea 

• Foods: Soy sauce, sauerkraut, kimchi 

Archaea Types: Methanogens

• Produce Methane, which is a atmospheric greenhouse gas 

• Methane Production 

• Natural sources (36%): wetlands, ocean archaea, termite guts 

• Human Driven (64%): Livestock digestive tract which are loaded w/ archaea that helps w/ digestion of plant matter, landfills and dumps create biogas energy 

• Number 1 Source of Methane production (not associated w/ archaea) is Fossil Fuel Combustion 

Bacteria types: Phylum Actinobacteria

• Gram positive

• Filamentous, forming branching species 

• Important agriculture, human health, forest areas bc they are abundant in soil and are important decomposers of dead plant and animal material 

• Free living Actinobacteria: Organic Matter Decomposition (Soils) and Nutrient Cycling 

• Mutualist (+/+) 

• Forms Biofilms - when bacteria secrete polysaccharide matrix and other organisms colonize on it (dental plaques)

• Used in Bioremediation - process to clean up soil/water contamination from heavy metal

Bacteria Types: Phylum Cyanobacteria

• Gram negative

• Found as independent cells, in chains that form filaments, or in loose aggregation of individual cells called colonies 

• Most abundant 

• “Blue Green Algae” 

• Photosynthetic Bacteria – they produce much of the oxygen, nitrogen, and organic compounds that feed organisms living in freshwater and marine environments 

• Strongly associated w/ algal blooms and poor water quality

• Abundant where N and P at High Levels (Eutrophication) 

Bacteria types: Phylum Firmicutes

• Gram-positive

• Extremely common in intestine where they live in symbiotic mutualism, aiding the digestive process 

• Many used in biological control 

• Used to control/kill another type of organism (Bacillus Thuringiensis (Bt)) 

• Respiratory (Streptococcus Pneumoniae)

• Cheeses, yogurt (Streptococcus Thermophilus)

• Skin Infections (Streptococcus Aureus)

Bacteria Trypes: (Phylum) Proteobacteria

• Gram negative

• Diverse in morphology and metabolism

• Geobacter Netallireducens (cleans up uranium)

• E Coli (Critical to digestive processes in mammals, common in sewage water pollution)

• Yersinia Pestis (causes disease like bubonic, black plague, pneumonic (respiratory infection)

• Used in Bioremediation