Introduction to Bacteria

Question 1

Why do scientists study bacteria? Briefly describe the biological impact, abundance, habitat diversity and medical importance of these organisms.

Answer 1

• research shows existence before eukaryotes
• found extreme habitats(extremophiles); relates to temp, salt concentrations, pressure
• could explain origins of life, help discover extraterrestrial life, and be used in the laboratory setting to study DNA and other subjects
• human body includes 100 trillion+ bacteria cells
• only few bacteria are pathogens for human body (disrupt bodily functions)
• Koch postulates helped develop causation link between bacteria and organism by studying anthrax bacteria in cattle
• Koch postulate led to studying of germ theory

Question 2

Virulence

Answer 2

Ability to cause disease; heritable trait that varies among individuals in a population

Question 3

Pathogenicity

Answer 3

the property of causing disease; the genome of a pathogenetic strain is bigger since it includes virulence genes and one coding for a toxin; the toxin enters a host cell, binds to ribosomes, and inhibits protein synthesis to kill the cell

Question 4

What are antibiotics?

Answer 4

molecules that kill bacteria or stop them from growing; produced naturally by soil-dwelling bacteria and fungi; proposed to reduce cell competition for resources

Question 5

What are drug resistance pathogenic bacteria?

Answer 5

bacteria exposed to extensive use of antibiotics; grow as biofilms(dense bacterial colonies enmeshed in a polysaccharide-rich matrix that helps shield the bacteria from antibiotics)

Question 6

What is the significance of bacteria developing resistance?

Answer 6

it creates a problem of antibiotics being less effective at treating illnesses or infection, putting the organism it is affecting at higher risk of serious complications

Question 7

What are enrichment cultures and how/why are they used?

Answer 7

• classical technique for isolating new types of bacteria and archaea is
• based on establishing a specified set of growing conditions—temperature, lighting, substrate, types of available food, and so on; Cells that thrive under the specified conditions increase in numbers enough to be isolated and studied in detail.

Question 8

Describe the human microbiome

Answer 8

• encompasses all the microbes that inhabit the body or parts of the body, such as the mouth, gut, and other tissues
• Humans harbor a diverse ecosystem of symbiotic prokaryotes. The human gut microbiome alone is composed of 100 trillion bacteria and archaea that play a key role in human health. Some microbes may make us sick, but we depend on many others to stay healthy. Changes in the gut microbiome, for example, have been linked to both inflammatory bowel disease and obesity

Question 9

Describe morphological diversity observed among bacteria

Answer 9

• size(from tenths of a micrometer to thousands of them)
• shape(filaments, spheres, rod, spiral)
• motility(flagella and amount)
• cell walls: gram positive(plasma membrame, extensive peptigoglycan) and gram negative(plasma membrane, thin peptigoglycan, and phospholipid bilayer)

Question 10

Define quorum sensing and bioluminescence

Answer 10

quorum sensing: The use of signaling pathways to respond to population density in prokaryotic and eukaryotic microbes; allows unicellular organisms to communicate and coordinate their activities

bioluminescence: light emission in bacteria

Example of bioluminescence: Vibrio fischeri are actively cultured in the light organs of the bobtail squid; after reaching a certain density, they express enzymes that catalyze a light-producing reaction