LO 1 Part 2 Flashcards
Describe the binomial system of nomenclature
- The generic (genus) name followed by the species name
- Genus is capitalized, species is lower case
- Both are italicized or underlined when italics aren’t available (such as handwriting)
What are the main 3 bacterial shapes?
- Spherical (cocci)
- Rod shaped (bacilli)
- Spiral shaped (vibrios, spirilla, spirochetes)
The prefix “Diplo” describes bacteria that prefer to live in _______
Pairs
The prefix “strepto” describes bacteria that prefer to live in _______
Chains
The prefix “staphylo” refers to bacteria who prefer to live in _______
Clusters
Describe the 3 spiral forms of bacteria (vibrios, spirilla, spirochaetes)
- Vibrios - are cells which resemble a comma. Typical representative is Vibrio cholerae
- Spirilla - are coiled forms of bacteria such as helicobacter pylori (causitive agent of stomach ulcers)
- Spirochaetes - flexuous (doesn’t have rigid cell wall of spirilla) spiral forms which include treponema (T.pallidium)
In addition to creating rigidity in a bacterium, the cell wall protects against _________
Osmotic damage
Chemically, the rigid part of the cell wall is made of _______
Peptidoglycan
Describe Gram staining
- First described by Gram in 1884
- Staining method used to study morphologic appearance of bacteria
- Bacteria can either be Gram positive (purple/blue) or Gram negative (pink/red)
- Staining is based on composition of cell wall
What do the membranes/cell walls of Gram-positive bacteria look like?
Cell membrane surrounded by thick layer of peptidoglycan (cell wall)
What do the membranes/cell walls of Gram-negative bacteria look like?
Inner membrane surrounded by thin layer of peptidoglycan covered in an outer membrane (LPS layer)
What are the 4 steps of Gram staining?
- Application of crystal violet (purple dye - primary stain )
- Application of iodine (moderant)
- Alcohol wash (decolorization)
- Application of fuchsine or safranin (pink dye - counter stain)
Describe Gram-positive bacteria
- Stain blue/purple
- Cell wall typically rich with peptidoglycan
- Lacks secondary membrane and lipopolysaccharide (LPS) layer of Gram-negative bacteria
Describe Gram-negative bacteria
- Stain red or pink because of the counter stain (due to higher lipid content)
- Have only a few layers of peptidoglycan
- Have secondary cell membrane primarily of lipopolysaccharide (LPS)
- Counter stained with safranin or fuchsine
Peptidoglycan readily absorbs _______
Crystal violet
Gram-positive infections are usually ______ severe because the body does not contain ______
Less; peptidoglycan
The human body produces the enzyme _______ that attacks the peptidoglycan layer of Gram-positive bacteria
Lysozyme
Gram-________ bacteria is much more susceptible to some antibiotics such as penicillin
Positive
What is lipopolysaccharide?
An endotoxin that increases severity of inflammation, fever, bone destruction, haemorrhage, and vomiting (body trying to get that shit OUT)
Define endotoxin
a toxin that is present inside a bacterial cell and is released when the cell disintegrates. It is sometimes responsible for the characteristic symptoms of a disease
Gram-______ bacteria are more pathogenic due to their outer membrane structure, which is often hidden by a ________
Negative;capsule or slime layer
______ bacteria neither stains blue-purple or pink-red
Gram variable
What 2 mediums are used to culture bacteria?
- Liquid form (broth medium) - appears cloudy during bacterial growth
- Semi-solid (agar medium) - polysaccharide plus other nutrients, typically used to obtain a “pure” culture
What are some different levels of oxygen requirements
- Obligate aerobes - require oxygen
- Microaerophiles - require low-oxygen environments
- Aerotolerant anaerobes - don’t use oxygen, but can tolerate some of it
- Facultative anaerobes - uses aerobic respiration if oxygen is available and fermentation if it isn’t
- Capnophiles - thrive in high concentrations of carbon dioxide
What are 3 groups of organisms based on temperature requirements for optimal growth?
- Thermophiles - found in hot water of geysers
- Mesophiles - optimal growth at body temp, dental carries, periodontal disease, pneumonia
- Psychrophiles - found in refrigerator
Most bacteria grow between pH ____ and _____
6.5 - 7.5
Molds and yeast grow between pH ____ and _____
5 and 6
Bacteria in the body survive between pH ___ and ___
5.5-8.5 (optimal 7.0)
______ bacteria produce acids during growth
Acidogenic
_____ bacteria survive and grow in acidic environments (below 5.5)
Aciduric
Acidogenic and aciduric bacteria are both important in the initiation and progression of ________
Dental caries
What nutrients do bacteria require for growth?
- Protein (amino acids)
- Lipids (fatty acids)
- Polysaccharides and monosaccharides
- Nucleic acids
- Vitamins
- Inorganic substances (sodium, potassium, etc.)
What are the 2 energy production methods an organism could use?
- Respiration
- Fermentation
Regardless of the energy production method, _______ is the source, and ____ is released
Glucose; ATP
Describe cellular respiration
- Glycolysis of sugars
- Requires use of oxygen and a process called the electron transport chain (ETC)
- End product is more ATP
Describe fermentation
- Anaerobic process
- Involves breakdown of sugar (glycolysis)
- End product - lactic acid
- Metabolic pathway responsible for dental caries
How do you control bacterial growth?
Prevent multiplication - change/ eliminate a physical/ nutritional requirement for growth by using a chemical agent that interferes with division
______ is an agent that prevents bacterial growth without killing them
Bateriostatic
What are some examples of bacteriostatics?
- Putting them in fridge/freezer
- Eliminate availability of oxygen
- Change pH
- Use of antibiotics
What are some methods of killing microorganisms?
- Bactericidal, virucidal, fungicidal or agents:
- High temps or pressures
- Antimicrobial agents in disinfectants, hand washing, mouth rinses (act on cytoplasmic membrane)
- Chlorhexidine gluconate affects the cell membrane and interferes with metabolism and uptake of nutrients by cells
__________ affects the cell membrane and interferes with energy metabolism and uptake of nutrients by cells
Chlorhexidine gluconate
Describe viruses
- A small amount of DNA or RNA wrapped in protein and sometimes a lipid membrane
- Individuals called virus particle or viron
- Lack enzymes needed for protein or nucleic acid synthesis - depend on infected cell’s machinery to multiply and disperse
- Multiply by complex process (not binary fission like bacteria)
- They are unaffected by antibiotics
Viruses are, by far, the ______ organisms
Smallest
Describe the structure of viruses
- Nucleic acid core surrounded by capsid (protein coat)
- May be further surrounded by an envelope (lipids, proteins, polysaccharides) that protect the capsid and nucleic acid of the virus
Describe viruses in dentistry
- Specific oral diseases - herpes, hand foot and mouth
- Diseases elsewhere in the body that impact mouth - measles
- Blood-borne diseases - hepatitis B or AIDS
- Other types that may be transmitted without use of proper infection control procedures - influenza
Viruses can infect _______
Animals, plants, fungi, algae, protozoa, or bacteria (bacteriophage, which can help control bacterial infections)
Describe viral replication
- Virus adsorbs to a surface of a living cell - attachment/adsorption
- Virus is taken into the cell where capsid is removed to release nucleic acid - penetration and uncoating
- Virus replicates - using host cell machinery
- Lytic cycle is now induced - persistent infection
What are the routes of viral infections?
- Damage/perforation of skin may permit viral infections - relevant to blood borne like hepatitis B
- Respiratory tract - major route for infections, e.g. common cold and chicken pox
- Alimentary tract (ingestion) and some spread through oropharynx (region of throat) - typically in saliva, e.g. herpes viruses
- Genital tract (sexual contact or trans-placental spread) - e.g. HIV
How do you control viral replication?
- Best approach is prevention via immunization and infection control
- Viruses can be killed outside of the body by exposure to heat or chemicals
- Antibiotics do not work on viruses
Describe prions
- Tiny strings of protein
- Name is derived from Proteinaceous infectious
- Cannot be classified as truly “living” - they are infectious agents made of only protein (no nucleic acid)
- They aren’t really microorganisms, but they are able to induce abnormal folding of normal cellular prion proteins in the brain, causing brain damage
________ is a gene in your DNA which encodes for prion protein
PRNP
_______ also known as ____ is a protein in the surface of your cells
Prion protein; PrP
A _______ is an infectious particle made up of misfolded prion proteins
Prion
Describe prion disease
- Rapidly progressive and always fatal
- All known prion diseases are collectively called transmissible spongiform encephalopathies (TSEs) and are untreatable
What is Creutzfeldt-Jakob Disease (CJD)?
- Noted for causing brain degeneration
- Believed to be derived from bovine spongiform encephalopathy (mad cow disease) which wiped out herds in the 80s
What is Kuru?
- Disease that was common among natives in Papua New Guinea, where women and children ate prions - infected human brains as part of traditional burial custom
What are the symptoms of a prion infection?
- Accumulation of abnormal prion protein in brain
- Memory, judgement and intellect are affected
- Insomnia and dementia
- Exactly HOW prions cause disease is unknown but it’s thought that prions convert normal proteins to non-functional ones by causing molecules to change their shape
Are prions easy to get rid of/control?
No, they are highly resistant to traditional sterilization methods because of the extreme stability of prion proteins
Describe fungi
- Mushrooms, molds, and yeasts
- In dentistry, we are concerned with oral candidiasis (thush, denture stomatitis)
Describe oral candidiasis (thrush, denture stomatitis)
- Caused by candida albicans
- May also cause vaginal infection, skin infection, or widespread infection
- Treated with anti-fungal agents
Describe candida albicans
- Present in normal flora of 30% of adults
- It is an opportunistic pathogen
- Causes harmful infections only when given special opportunity - depressed immune system (AIDS), Changes in physiology of body, immature body defense (newborn), trauma to tissue (ill-fitting dentures), long-term antibacterial activity therapy
Describe fungal structure
- Eukaryotic cells
- Mostly strict aerobes, some grow anaerobically, none are strict anaerobes
Describe fungal division
- Can be sexual or asexual
- Branching hyphae form mycelium
- Spherical cells multiply by budding and division
Describe the development of penicillin
- Was the first antibiotic and was developed from the Penicillin notatum mold by sir Alexander Fleming
- Although its derivatives are still in use, most antibiotics are now developed from bacterial strains
- Discovered by accident - agar plate of Staphylococcus bacteria contaminated with Penicillin notatum which inhibited growth
Name some benefits of fungi
Molds are also used to make enzymes, citric acid, and other organic acids used to make bleu cheese, Roquefort, and camembert
Name and describe 3 protozoal diseases
- Trypanosoma brucei - causes African sleeping sickness, ciliated protozoa transmitted by tsetse fly bites, treatable, but no vaccine
- Balantidium coli - pathogenic ciliate that causes dysentery, inflammatory disorder of intestine, usually spreads by contaminated drinking water (🐖💩)
- Plasmodium spp. - cause of malaria, mosquito-borne
Protozoa are divided in 2 groups depending on locomotion. What are those groups?
- Amoeba
- Flagellated protozoa
Describe Amoeba
- Extend a pseudopodium in the direction they want to move and the rest of the cell flows into it (amoeiboid movement)
- When ingesting food particles, it will surround with pseudopodia which fuse together and form into a vacuole (phagocytosis - white blood cells work in this way too)
Describe flagellated protozoa
- Moves in a whip-like flagella movement
- Some are pathogenic for example the Trypanosoma brucei sub-species that are transmitted by tsetse flies
