Microbiology Chapter on Fermentation and Bacteria
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Questions and Answers

Which of the following compounds are produced by the fermentation of complex plant-derived carbohydrates?

  • Butyric acid (correct)
  • Nitric oxide
  • Ammonia
  • Phenol

Acetate is unrelated to obesity.

False (B)

Name two neuroactive compounds found in the metabolites of undigested protein.

Nitric oxide, Tryptamine

Which of the following bacteria are considered obligate anaerobes?

<p>Bifidobacterium (D)</p> Signup and view all the answers

A high-fat diet promotes an increase in __________, which is a sulphite-reducing pathobiont.

<p>Bilophila wadsworthia</p> Signup and view all the answers

Match the following metabolites with their effects:

<p>Nitric oxide = Vasodilation Sulphide-containing metabolites = Induce IBD Polyamines = Cell growth regulation SCFAs = Energy source for host cells</p> Signup and view all the answers

Facultative anaerobes can only survive in the presence of oxygen.

<p>False (B)</p> Signup and view all the answers

What is the primary benefit of oligosaccharides found in human milk for infants?

<p>They promote the growth of bifidobacterial in the intestine.</p> Signup and view all the answers

Breastfeeding for the first six months provides bioactive factors such as lysozyme, lactoferrin, and ______.

<p>immunoglobulins</p> Signup and view all the answers

Match the following bacteria with their classification:

<p>Enterobacteriaceae = Facultative anaerobes Bifidobacterium = Obligate anaerobes Veillonella = Obligate anaerobes Staphylococci = Facultative anaerobes</p> Signup and view all the answers

What is the primary function of inclusions in cells?

<p>To segregate certain cellular components (C)</p> Signup and view all the answers

Endospores are capable of increasing the number of bacterial cells.

<p>False (B)</p> Signup and view all the answers

What is the term for the process of forming endospores?

<p>Sporulation</p> Signup and view all the answers

Gram-positive bacteria typically have a thick _________ layer that provides protection.

<p>peptidoglycan</p> Signup and view all the answers

Which stage comes last in the process of activating an endospore?

<p>Outgrowth (B)</p> Signup and view all the answers

Match the bacterial cell structures with their descriptions:

<p>Inclusions = Formed by the aggregation of substances Endospores = Dormant cells formed in response to nutrient depletion Peptidoglycan = Mesh-like layer for structural support Sporulation = Process of forming endospores</p> Signup and view all the answers

Endospores can withstand exposure to heat and chemical disinfectants.

<p>True (A)</p> Signup and view all the answers

What is the first stage of the process from endospore to active vegetative cell?

<p>Activation</p> Signup and view all the answers

What is the primary component of the outer membrane of Gram-negative bacteria?

<p>Lipopolysaccharides (LPS) (B)</p> Signup and view all the answers

LPS is primarily composed of protein.

<p>False (B)</p> Signup and view all the answers

What is another name for lipopolysaccharide (LPS) due to its effect on the immune response?

<p>endotoxin</p> Signup and view all the answers

The O-side chain of LPS is also called the _____ because it elicits an immune response.

<p>O antigen</p> Signup and view all the answers

Match the components of Lipopolysaccharide (LPS) with their descriptions:

<p>Lipid A = Contains two glucosamine sugar derivatives with fatty acids and phosphate Core polysaccharide = Constructed of about 10 sugars O-side chain = Extends outwards from the core and contains unusual sugars Endotoxin = Stimulates the innate immune response</p> Signup and view all the answers

What role does the core polysaccharide play in LPS?

<p>Stabilizes the outer membrane structure (D)</p> Signup and view all the answers

LPS can induce fever and shock in the host organism.

<p>True (A)</p> Signup and view all the answers

How does LPS help protect pathogenic bacteria from host defenses?

<p>By creating a permeability barrier and contributing to a negative charge on the bacterial surface.</p> Signup and view all the answers

What is the primary function of enterocytes in the GI tract?

<p>Absorb nutrients (B)</p> Signup and view all the answers

Goblet cells are mainly involved in the absorption of nutrients in the gastrointestinal tract.

<p>False (B)</p> Signup and view all the answers

What layer of connective tissue lies underlying the epithelium in the GI tract?

<p>lamina propria</p> Signup and view all the answers

The major component of the intestinal mucus layer is _____, which is a hydrated gel.

<p>MUC2</p> Signup and view all the answers

Which of the following is produced by the action of bile salt hydrolase?

<p>Deoxycholate (D)</p> Signup and view all the answers

Which of the following structures is NOT considered a special anatomic structure of mucosal immunity in the GI tract?

<p>Thymus (D)</p> Signup and view all the answers

95% of bile acids are typically reabsorbed by the body.

<p>True (A)</p> Signup and view all the answers

What nutrient is metabolized into trimethylamine (TMA)?

<p>Choline</p> Signup and view all the answers

Match the cell type with its function in the gastrointestinal tract:

<p>Enterocytes = Absorb nutrients Goblet cells = Produce mucus Epithelial cells = Form tight junctions Immune cells = Respond to pathogens</p> Signup and view all the answers

Pro-inflammatory cytokines can stimulate mucin gene expression in goblet cells.

<p>True (A)</p> Signup and view all the answers

Bile acids are synthesized by enzymes in the ______.

<p>liver</p> Signup and view all the answers

What do the tight junctions between epithelial cells in the GI tract prevent?

<p>Migration of microbes into the lamina propria</p> Signup and view all the answers

Match the following bacteria with their role in bile salt metabolism:

<p>Bacteroides = Deconjugation of bile acids Eubacterium = Deconjugation of bile acids Clostridium = Deconjugation of bile acids Actinobacteria = Minor role in bile salt metabolism</p> Signup and view all the answers

What significant health risk is associated with the microbial conversion of choline?

<p>Cardiovascular diseases (A)</p> Signup and view all the answers

Trimethylamine-N-oxide (TMAO) is produced from dietary choline along with promoting adipose tissue inflammation.

<p>True (A)</p> Signup and view all the answers

Name one consequence of increased levels of trimethylamine-N-oxide (TMAO) in the body.

<p>Promotes atherosclerosis</p> Signup and view all the answers

Flashcards

Inclusions

Cellular compartments that separate specific components within the cytoplasm, preventing free diffusion.

Endospores

Dormant bacterial cells formed inside a mother cell, highly resistant to harsh conditions.

Sporulation

The process of forming endospores in bacteria, triggered by nutrient depletion.

Activation

The first stage of endospore reactivation, preparing it for germination.

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Germination

The breaking of the dormant state in an endospore, leading to cell growth.

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Outgrowth

The final stage of endospore reactivation, involving water uptake and enzyme activity.

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Complex cell wall

A rigid, mesh-like structure surrounding bacteria, providing environmental protection.

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Gram positive bacteria

Bacteria with a thick peptidoglycan cell wall, offering significant protection.

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Facultative Anaerobes

Bacteria that can survive with or without oxygen, commonly found in the gut during infancy.

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Obligate Anaerobes

Bacteria that can only survive without oxygen, they die when exposed to oxygen. They dominate the infant gut after the first few months.

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Oligosaccharides in Breast Milk

Complex sugars found in human milk that promote the growth of beneficial bacteria like Bifidobacterium.

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Fermentation of Oligosaccharides

The process where Bifidobacteria break down oligosaccharides in breast milk, producing acetate and lactate, providing energy for the growing baby.

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Bioactive Factors in Breast Milk

Factors present in breast milk that support the development and maturation of the infant's gut, immune system, and metabolism.

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LPS (Lipopolysaccharide)

A potent stimulator of the innate immune response, found in the outer membrane of Gram-negative bacteria.

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Lipid A

The lipid component of LPS, responsible for its immune-stimulating properties.

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Core Polysaccharide

A chain of sugars attached to Lipid A in LPS, contributing to the negative charge of the bacterial surface.

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O-side Chain (O-antigen)

The outermost part of LPS, composed of unusual sugars, that extends outwards from the core polysaccharide.

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Pyrogenicity

The ability of LPS to induce fever in the host.

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Endotoxic Shock

The capacity of LPS to trigger a potentially life-threatening immune response, leading to shock and organ dysfunction.

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LPS Binding to TLR4

The process by which LPS binds to specific receptors on immune cells, activating the immune response.

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Antimicrobial Resistance

The ability of LPS to confer resistance to antimicrobial agents in some bacteria.

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What are SCFAs and their role in the gut?

Short-chain fatty acids (SCFAs) like butyric acid and acetic acid, produced by bacteria in the gut from dietary fibers, serve as a major energy source for host cells.

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How might acetate from SCFAs relate to obesity?

Acetate, a type of SCFA, has been linked to obesity. This suggests a potential connection between gut bacteria, SCFA production, and weight gain.

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How does a high-fat diet affect gut bacteria?

High-fat diets can disrupt the balance of gut bacteria, leading to an increase in harmful bacteria and a decrease in beneficial ones. This imbalance, known as dysbiosis, can contribute to inflammation and other health issues.

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What is B. wadsworthia and how is it linked to high-fat diets?

B. wadsworthia, a type of bacteria that breaks down sulfur compounds, thrives on high-fat diets. Its overgrowth is associated with inflammation and obesity.

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What happens to undigested protein in the large intestine?

Undigested protein in the large intestine is broken down by bacteria into various metabolites, including neuroactive compounds like nitric oxide, tryptamine, and H2S. These metabolites can have both beneficial and harmful effects on the body.

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Enterocytes

Specialized cells that line the gastrointestinal tract, responsible for absorbing nutrients.

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Goblet cells

Cells that produce mucus, a viscous substance that forms a protective barrier against microbes in the gut.

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Tight junctions

Proteins that form tight junctions between epithelial cells, preventing microbes from entering the lamina propria.

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Defensins

Antimicrobial peptides secreted by epithelial cells, acting as a defense against invading microbes.

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Toll-like receptors (TLRs)

Specialized receptors on epithelial cells that recognize and bind to pathogen-associated molecular patterns (PAMPs), triggering immune responses.

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Lamina propria

A layer of loose connective tissue beneath the epithelial lining of the gastrointestinal tract, containing blood vessels, lymphatic vessels, and immune cells.

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Lamina propria follicles

Small, localized collections of immune cells within the lamina propria, contributing to mucosal immunity.

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Mucosa-associated lymphoid tissue (MALT)

A type of immune tissue located in the gastrointestinal tract, playing a crucial role in the adaptive immune response to gut antigens.

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What are bile acids?

Steroid acids produced by the liver to eliminate excess cholesterol. 95% are reabsorbed, while the rest undergo deconjugation by gut microbiota.

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What is bile salt deconjugation?

A process where bile salts are broken down by gut bacteria, producing deoxycholate, ursodeoxycholate, and lithocholate.

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What is choline?

A water-soluble nutrient essential for cell membrane integrity and neurotransmission.

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What is trimethylamine (TMA)?

A metabolic byproduct of choline produced by gut bacteria. Associated with increased risk of cardiovascular disease.

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What is trimethylamine-N-oxide (TMAO)?

A compound formed in the liver from TMA. It promotes inflammation, atherosclerosis, and insulin resistance.

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What is the microbial conversion of choline?

The process by which gut bacteria convert dietary choline into TMA, which is further metabolized into TMAO in the liver.

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Which gut bacteria are involved in bile salt deconjugation?

Anaerobic bacteria like Bacteroides, Eubacterium, and Clostridium are involved in bile salt deconjugation.

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Besides anaerobic bacteria, which other microbes participate in bile salt deconjugation?

Aerobic bacteria like Actinobacteria and Proteobacteria also play a role in bile salt deconjugation, though to a lesser extent.

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Description

This quiz explores the fascinating world of microbiology, focusing on fermentation processes, bacterial classifications, and the benefits of oligosaccharides in human milk. Test your knowledge on neuroactive compounds, anaerobic bacteria, and key metabolites. A perfect way to solidify your understanding of these essential biological concepts.

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