-
Defenses of the GI tract
- mucus
- secretory IgA
- peristalsis
- some fluids have antimicrobial properties: saliva, stomach fluid, and bile
- GALT tissues (gut associated lymphoid tissues): tonsils, adenoids, lymphoid tissue, in the esophagus, Peyer's patches, and appendix
-
Define peridontitis
What can it cause?
- Extension of gingivitis into the periodontal membrane and cementum
- Increases the size of pockets between the tooth and the gingival
- Can cause bone resorption enoughg to loosen and lose the tooth
-
The most common infections disease of human beings is:
Dental Carries
-
1) Initial stage of periodontitis:
2) If this persists it can:
- 1) gingivitis
- 2) develop extension of gingivitis into the periodontal membrane and cementum; and increase the size of pockets between the tooth and gingiva. Can also cause bone reabsorption enough to loosen and possibly lose teeth. (the definition of periodontitis)
-
Mumps is caused by:
Initial symptoms
- The paramyxo virus
- Fever,malaise, ms pain
-
The initial symptoms of mumps may be followed by...
- Inflammation of the salivary glands producing popherlike swelling of the cheeks
- AKA- parotitis
-
__________ is a ________ that causes gastric ulcers
Also linked to a variety of gastrointestinal ailments:
- Heliobacter pylori; bacteria
- Gastritis
- Deodenal ulcers
- Severe ulcers
- Long term infection can cause stomach adenocarcinomas
-
0157:H7
Enterohemorrhagic E. coli (EHEC)
-
EHEC causes symptoms of:
- bloody diarrhea
- some pts can develop hemolytic uremic syndrome (HUS)
- Can also cause neurological symptoms
-
Salmonella typhi AKA
Typhoid fever
-
Shigella symptoms
- Causes acute diarrhea
- Causes the most severe forms of dysentery (watery stools)
-
Enterotoxigenic E. coli (ETEC) AKA
Symptoms
- Traveler's diarrhea
- fever, nausea, vomitting, watery diarrhea
-
Campylobacter
Source
In rare cases can lead to
- Most common BACTERIAL cause of diarrhea in US
- Is an STD that affects sheep, goats, and cattle and can cause spontaneous abortions in women late term
- Comes from chicken
- In rare cases, it can cause Guillian-Barre syndrome
-
Clostridium difficile
Major cause of...
Can cause...
Treated with...
- Major cause of diarrhea in hospitals: nosocomial infection
- Causes pseudomembranous colitis
- Produces 2 enterotoxins that create areas of necrosis in the wall of the intestine
- Is treated with Flagyl
-
Vibrio cholera
Symptoms
- Symptoms begin abruptly
- Copious watery feces called secretory diarrhea
-
Cryptosporidium
In certain people...
Can cause...
In AIDs pts, may develop into chronic persistent cryptosoridial diarrhea
-
Rotavirus
- Causes damage to the intestine
- Primary VIRAL cause of diarrhea worldwide
- Infects humans, calves, and piglets from fecally contaminated food
-
Ascaris lumbricoides
- Larvae/ worms
- Can emerge from the nose and mouth
-
Necator americanus
- Larvae/ worms
- Infects by penetrating the bare feet
- Can be carried through the blood to the heart and lungs
-
Facilitated diffusion
- Utilizes a carrier protein
- Exhibits saturation which limits the rate of a substance if there are a low number of binding sites on the transport proteins
-
Active transport
Examples
- Requires the expinditure of energy
- Items that require actve transport are: AA, organic acids, phosphates, and metal ions
- Example is endocytosis
-
Environmental factors that affect microbes
- Microbial cells cannot control thier temp, so they assume the ambient temp of thier environment
- Optimum temp: promotes the fastest growth
- pH
- Osmotic pressure
- Barometric pressure
-
Psychrophile
- A microorganism that has an optimum temp below 15d C and is capable of growing at 0d C
- Listeria is an example
-
Mesophile
- Optimum growth temperature of most mesophiles is 20-40d C (room temperature)
- Most human pathogens are mesophiles and have optimum between 30-40d C
-
Thermophile
- A microbe that grows optimally at temperatures greater than 45d C
- Likes warmer environment
-
Obligate (strict) aerobe:
Cannot grow without oxygen
-
Facultative
An aerobe that is also capable of growth in the absence of oxygen
-
Obligate (strict) anaerobes
Cannot tolerate any free oxygen in the immediate environment and will die if exposed to it.
-
Aerotolerant anaerobes
Do not utilize oxygen, but can survive and grow to a limited extent in its presence
-
Microaerophile
Does not grow at normal atmospheric concentrations of oxygen but does require a small amount of oxygen in metabolism
-
Majority of organisms live or grow in habitats b/t _______ pH
6-8
-
Osmophiles vs. Halophiles
- Osmophiles live in high solute (sugar) concentrations
- Halophiles prefer high salt concentrations
-
Mutualism
A type of symbiosis in which both organisms benefit
-
Commensalism
A type of symbiosis in which one organism is benefited and the other is unaffected
-
Parasitism
A type of symbiosis in which one organism is benefited and the other is harmed
-
Synergism vs. Antagonism
- Both are types of non-symbiotic relationship
- Synergism- Free living organism; organisms benefit, but isnt necessary
- Antagonism- Free-living species that arise when members of the community compete; one microbe secretes a chemical substance into the environment that inhibit or destroys another microbe in the same environment
-
Binary fission
The basis of population growth
-
2 ways microbial growth occurs
- Growth takes place on 2 levels
- - cell snthesizes new cell components and increases in size
- - the number of cells in the population increases
-
The population growth curve
- Is a predictable pattern
- Has 4 phases
- Lag phase: flat period, first part of curve, not yet multiplying at optimal rate
- Eponential growth phase: maximum cell division
- Stationary growth phase: death balances out the rate of multiplication, depleted nutrients and oxygen stores
- Death phase
-
Enumeration of bacteria
Total cell count
-
Chromosomes in bacteria are ________ in shape
circular
-
Basic unit of DNA structure is a
Nucleotide
-
-
Nitrogenous base pyrimidines
-
Helicase
Binds to the DNA at origin and unzips the DNA helix by breaking hydrogen bonds
-
Function of DNA poymerase III in DNA replication
- Can only continue to add nucleotides to an already existing chain, so start with RNA primers put on first by enzyme primase
- Proofreads the chain for mistakes
-
Primary function of primase
Synthesizing an RNA primer
-
Function of DNA polymerase I in DNA replication
- Removes RNA primers and replaces them with DNA
- Closes gaps
- Repairs mismatches
-
Primary function of ligase
- Final binding of nicks in DNA during during synthesis and repair
- Connects the Okazaki fragments
-
Occasionally an incorrect base is added to the growing chain. If this is not corrected, ________ result
Mutations
-
Okazaki fragments
Short fragments of DNA which are linked together by ligases
-
The master code of DNA is used to synthesize an RNA molecule through a process called:
Transcription
-
The information in the RNA is used to produce proteins through a process called
Translation
-
Each triplet represents a code for a particular _________
Amino Acid
-
When the triplet code is transcribed and translated, it dictates the type and order of Amino Acids in the __________
Polypeptide chain
-
RNA vs. DNA
- RNA
- - A single stranded molecule
- - Contains uracil
- - Sugar is ribose
- DNA
- - Double stranded
- - Contains thyamin
- - Sugar is deoxyribose
-
Function of mRNA
- Carries out DNAs message
- A transcription of a structural gene or genes in the DNA
-
Function of tranfer RNA
- The key to Translation
- A copy of a specific region of DNA
- Brings AA to ribosome during tranlation
-
Function of rRNA
Forms the major part of a ribosome and participates in protein synthesis
-
Biota
Beneficial or harmless resident bacteria commonly found on and/or in the human body
-
Prokaryotic ribosome is composed of tightly packed _____ and __________
rRNA; Protein
-
The second stage of gene expression
Translation
-
Modifications to proteins may be necessary if:
- The starting AA is clipped off
- Cofactors are added
-
Operons
- Collections of genes
- All are regulated as a single unit
-
2 types of operons
- Inducible: the operon is turned on (or induced) by the substrate of the enzyme for which the genes code
- Repressible: turned off by the product synthesized by the enzyme
-
Mutations
- An alteration in the nitrogen base of DNA
- When phenotypic changes are due to changes in the genotype
-
Wild type vs. mutant strain
- Wild type: a microorganism exhibits a natural, nonmutated characteristic
- Mutant strain: when the microorganism bears a mutation
-
Spontaneous mutation:
Random change in the DNA arising from errors in replication
-
Induced mutation:
Results from exposure to known mutagens
-
Point mutations:
Involve addition, deletion, or substitution of single bases
-
What are the 4 types of point mutations?
- Missense
- Nonsense
- Silent
- Back
-
Missense vs. nonsense
- Missense: change that leads to placement of a diffferent AA
- Nonsense: changes a normal codon into a stop codon
-
Silent mutation:
Alters a base but does not change the AA and thus has no effect
-
Back mutation
When a gene undergoes a mutation and then reverses back to its orginal base composition
-
Frameshift mutations:
Mutations that occur when one or more bases are inserted into or deleted from a newly synthesized DNA strand
-
Polymerase I and Polymerase III can both read for mutations
-
Recombinant organism:
Any organism that contains (and expresses) genes that originated in another organism
-
Types of Intermicrobial Exchange
- Conjugation- Donor cell with pilus; direct; genes transferred- toxin production
- Transformation- Free donor DNA; Indect; genes transferred- Polysaccharide capsule
- Transduction- Defective bacteriophage is carrier of donor DNA; Indirect; genes transferred- Toxins
-
Bacteriophage
A virus that specifically infects a bacterial cell
-
Repair of mutations- DNA that has been damaged by UV radiation
Restored by photoactivation or light repair
-
Repair of mutations- Excision repair
- Excise mutations by a series of enzymes
- Remove incorrect bases and add correct one
-
Repair of mutations- Most DNA damage is resolved by
Enzymatic systems specialized for finding and fixing such defects (DNA polymerase I and III)
-
Jaundice
- Yellow discoloration of the skin and other membranes caused by accumulation of bilirubin
- Associated with liver infection as with Hepatitis infections
-
Eosiniphilia
An increase in eosinophil concentration in the bloodstream commonly due to helminth infections
-
-
Hep B
- Fluid-borne
- Can develop into liver disease
- Can be oncogenic
-
Hep C
- Blood-borne
- Oncogenic
- Usually will need transfusions
-
-
Staphylococcus aureus
- Exotoxin
- Found in potato salads, custards, and pastries
- Heating wont prevent disease
- Wont alter the smell or taste of the food
-
Clostridium perfringens
- Exotoxin
- Caused when vegetables or beans have not been cooked thoroughly enough to destroy endospores
-
Bacillus cereus
- Exotoxin
- Found in foods that are kept warm for long periods of time
-
Giardia
- Stools have a greasy, malodrous quality
- Causes lots of flatulence
-
Taenea solium
Intestinal distress as the primary symptom
-
Contributing factor to dental caries
-
When symptoms are violent and incubation period is short, ________________ should be considered rather than ______________
Intoxication; infection
-
Food poisening is usually caused by an
Exotoxin
-
Virulence factors
- Specialized mouthparts
- Enzymes
- Cuticle or other covering
-
The definitive host is where the ________ __________ is found
Adult worm
-
Trace elements
Micronutrients (Zinc, Nickle, Mn) that occur in small amounts and are involved in enzyme function and maintenence of protein structure
-
Essential nutrients must be
provided to the organism in the diet
-
Obligate intracellular parasite
Must grow and live inside the host
-
Heterotrophs
An organism that relies on organic compounds for its carbon and energy needs
-
Where do heterotrophs get thier carbon?
From glucose (in organic form)
-
Autotrophs get their carbon from
Inorganic sources (CO2)
-
CHOPS N
- Carbon
- Hydrogen
- Oxygen
- Sulfur
- Nitrogen
-
Roles and resources of CHOPS N
-
Conjugated enzymes
Contain protein and non-protein molecules
-
Endoenzyme vs. exoenzyme
- Endoenzyme is the breakdown of molecules inside of the cell (function of virulence factors)
- Exoenzyme breaks down molecules outside the cell
-
Cofactors
- Support the work
- Metallic cofactors: activate enzymes and bring the active site and substrate closer together; inorganic
- Coenzymes: form an alteration of a substrate; removes a chemical group; Vitamins are one of the most important components of coenzymes; organic
-
Haloenzyme
- A conjugated enzyme
- A combination of a protein and one or more cofactor
-
Catalase
Breaks down hydrogen peroxide
-
Oxidase
Adds electrons to oxygen
-
Urease
Splits urea into an ammonium ion
-
Nitrate reductase
Reduces nitrate to nitrite
-
DNA polymerase complex
Synthesis of DNA
-
Fermentation end products
- Alcoholic beverages
- Dairy products
- Vitamins
- Hormones
- Antibiotics
-
Constitutive vs. regulated enzymes
- Constitutive: Present in bacterial cells in constant amount
- Regulated: The extent of transcription and translation is influenced by changes in the environment
-
3 ATP formation mechanisms
- Oxidative phosphorylation
- Substrate level phosphorylation
- Photophosphorylation
-
Competitive inhibition
Blocks the active site
-
Non-competitive Inhibition
Has 2 binding sites: regulatory and active
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