Unit 1 and 2 Microbiology

What is microbiology?

The study of microorganisms too small to be seen without magnification

What are microbes?

Microscopic living organisms such as bacteria

What are pathogenic microbes?

Microorganisms that cause disease in a host

What are non-pathogenic microbes?

Microbes that do not cause disease and are part of normal flora

What are opportunistic microbes?

Microbes that normally cause no harm but can cause infection when host defenses are weakened

What are saprophytic microbes?

Microbes that feed on dead or decaying organic matter

What is indigenous microflora?

Microbes that naturally live and grow in a specific region or environment

Why is microbiology important for dental hygienists?

It helps understand infection control

What is infection control?

Methods used to prevent spread of microorganisms and disease in dental settings

Who is the father of microbiology?

Antonie van Leeuwenhoek

What are historical milestones in microbiology?

Discovery of microorganisms

What is the unit of measurement for microbes?

Micrometer (µm)

How do microbes shape our planet?

They recycle nutrients, produce gases, and support plant and animal life

What are probiotics?

Beneficial microbes that support host health

How many microbes typically live in or on the human body?

Around 100 trillion

What is a pathogenic example in dentistry?

Streptococcus mutans causing dental caries

What are the main groups of microorganisms?

Bacteria, archaea, protozoa, fungi, helminths, and viruses

What is taxonomy?

The science of classifying living organisms

Who developed taxonomy?

Carl Linnaeus

What is nomenclature?

The system of naming organisms scientifically

What is binomial nomenclature?

Naming organisms using genus and species (e.g., Streptococcus mutans)

What is classification?

Organizing organisms into hierarchical ranks

What is identification in microbiology?

Determining characteristics of organisms to classify them

What are the three domains of life?

Archaea, Bacteria, and Eukarya

What is the main difference between prokaryotic and eukaryotic cells?

Prokaryotes lack a nucleus and membrane-bound organelles, eukaryotes have them

What are examples of eukaryotic cells?

Animal, plant, fungal, protozoan, and algal cells

What are examples of prokaryotic cells?

Bacteria and archaea

How is DNA packaged in prokaryotes?

It is free-floating in the cytoplasm

How is DNA packaged in eukaryotes?

Enclosed in a membrane-bound nucleus and associated with histones

What are bacterial cell walls made of?

Peptidoglycan

What are archaeal cell walls made of?

Unique chemicals distinct from bacteria and eukaryotes

What is the function of the cell wall?

Provides shape and prevents cell rupture or collapse

What is the cytoplasmic membrane?

A lipid-protein layer that controls transport of substances in and out of the cell

What is cytoplasm?

A viscous fluid inside the cell containing enzymes

What are mesosomes?

Inward foldings of the cytoplasmic membrane in some bacteria that help with cell division

What is the capsule?

A gelatinous polysaccharide or protein layer protecting bacteria and aiding in adhesion

What is the slime layer?

A loose glycocalyx that protects against water loss and nutrient depletion

What is the glycocalyx?

A polysaccharide coating that helps bacteria adhere to surfaces and form biofilms

What is a biofilm?

A community of microorganisms adhering to a surface, such as dental plaque

Why is the glycocalyx important in dentistry?

It contributes to dental plaque formation and makes bacteria more resistant to antibiotics

What are flagella?

Whip-like structures that provide bacterial motility

What are fimbriae and pili?

Surface appendages used for attachment (fimbriae) and genetic exchange (pili)

Which structure allows gene transfer between bacteria?

Pilus (through conjugation)

What are bacterial spores?

Dormant, resistant structures formed under harsh conditions

Which bacterial genera form spores?

Bacillus and Clostridium

Why are spores important in dentistry?

Used to test autoclave sterilization effectiveness (e.g., Bacillus stearothermophilus)

What is the significance of the bacterial outer membrane?

Found in Gram-negative bacteria; contains endotoxins that can cause fever and inflammation

What is endotoxin?

A toxic component of Gram-negative bacteria released after cell death

What is the Gram stain used for?

Differentiating bacteria into Gram-positive (purple) and Gram-negative (pink/red)

Which bacteria are more sensitive to penicillin?

Gram-positive bacteria

What is acid-fast staining used for?

Identifying Mycobacterium tuberculosis

What are bacterial shapes?

Cocci (spherical), Bacilli (rod-shaped), Spirochetes (spiral)

What are bacterial arrangements?

Diplococci (pairs), Streptococci (chains), Staphylococci (clusters)

What are examples of spiral bacteria?

Vibrio, Spirilla, Spirochetes

What diseases are caused by spirochetes?

Syphilis (Treponema pallidum) and Lyme disease (Borrelia burgdorferi)

What is Vibrio cholerae known for?

Causing cholera

What is Helicobacter pylori associated with?

Stomach ulcers and gastritis

What is bacterial growth?

Increase in number of cells through binary fission

What factors influence bacterial growth?

Temperature, pH, nutrients, oxygen, and water

What are the temperature groups of bacteria?

Psychrophiles (cold), Mesophiles (body temp), Thermophiles (heat)

Which bacteria grow best at body temperature?

Mesophiles

What are thermophiles used for in dentistry?

Testing sterilizer function because of heat resistance

What are the four oxygen groups of bacteria?

Obligate aerobes, Microaerophiles, Obligate anaerobes, Facultative anaerobes

Which bacteria survive without oxygen?

Obligate anaerobes

Which bacteria can grow with or without oxygen?

Facultative anaerobes

Which bacteria require oxygen?

Obligate aerobes

What is the optimal pH range for most human bacteria?

5.5 to 8.5

What are acidogenic bacteria?

Bacteria that produce acid

What are aciduric bacteria?

Bacteria that survive in acidic environments

How do acidogenic and aciduric bacteria relate to dentistry?

They cause enamel demineralization and dental caries

Why is water important for bacterial life?

It dissolves nutrients and supports enzymatic reactions

What enzymes in saliva help digestion?

Amylase and lingual lipase

What are eukaryotic examples relevant to microbiology?

Fungi, Protozoa, Algae, Helminths

What are fungi?

Eukaryotic organisms that can be unicellular (yeasts) or multicellular (molds)

What is the kingdom fungi divided into?

Macroscopic fungi (mushrooms) and microscopic fungi (molds

What is the dental relevance of fungi?

Can cause oral infections like candidiasis (thrush)

What are opportunistic fungal infections?

Infections like thrush in immunocompromised patients

What is Candida albicans?

A yeast that can cause oral or vaginal infections

What are saprophytic fungi?

Fungi that live on decaying matter and recycle nutrients

What are parasitic fungi?

Fungi that invade living tissue causing mycotic infections

What are protozoa?

Unicellular eukaryotes that move and feed like animals

What diseases are caused by protozoa?

Malaria and amoebic dysentery

What are helminths?

Multicellular parasitic worms such as tapeworms

How do helminths infect humans?

Through contaminated food, water, or soil

What is a definitive host?

The host where a parasite reaches maturity (humans for many helminths)

What is the size order from largest to smallest organism?

Helminth > Protozoan > Bacterium > Virus

What are viruses?

Acellular infectious agents that require a host to replicate

What is the clinical significance of archaeal microbes?

Possible link to periodontal disease

What is taxonomy’s dental importance?

Helps identify microbes relevant to oral health and infection control

What is microbiology’s overall significance in dental hygiene?

Understanding microbes helps prevent infections