Midterm 2 Flashcards
What are the five major branches of eukaryotic microorganisms?
Fungi: yeasts, molds, or fleshy fungi
Algae: photosynthetic
Protozoans: single celled eukaryotes with animal characteristics
Slime molds: can be single celles or multicellular mold
Helminths: parasitic worms
Describe fungi
Appear as yeast, molds, fleshy fungi
Few fungi are pathogenic (<1%)
Generally grow as filamentous, multicellular organisms
Form filaments called hyphae or unicellular organisms
Have cell wall composed of strong flexible polysaccharides called chitin
What is mycelium?
A collective mass of hyphae
Describe yeast
Single cells that reproduce by budding
Some may become multicellular by connecting budding cells
May require oxygen or grow in absence of oxygen
What is saccharomyces cerevisiae?
A model budding yeast
Describe molds
Rapidly growing
In an appropriate environment, hyphae grow to form a myeclium
Generally, hyphae have cross walls called septa
Some have coenocytic hyphae (no septa)
What is the purpose of septa?
Divide the hyphae into distinct uninuclear, cell-like units called septate hyphae
What are the classifications of fungi?
Basidiomycota: mushrooms and fruiting bodies
Lichens: consists of hyphae of a fungus and Cyanobacteria or green algae, symbiotic
Zygomycota: multinucleate molds
Ascomycota: primary fungi causing food spoilage (penicillium)
Describe ascomycota
Sac fungi, includes molds with septatehyphae and some yeasts
Asexual spores usually produced in long chains from the conidiophore
Detach from chain at slight disturbance and float in air like dust
When does an ascospore form?
Forms when the nuclei of two cells that can be either morphologically similar or dissimilar fuse
Spores are produced in saclike structure called ascus
Describe the life cycle of fungi
All fungi have some form of asexual reproduction
Most can also reproduce sexually which introduces variation
Often occurs during changing environment
Filamentous fungi reproduce by fragmentation of their hyphae and by spore formation
Yeast bud
Describe asexual reproduction by fungus
Sporangia release spores into the environment
Spores can cause infection after inhalation
Sporangiospores form in sporangium and spores release when ruptured
Conidiospores are produces at tip or sides of hyphae, no sac, pinch off at tip of a fertile hyphae - or segmentation of a preexisting végétative hyphae
Describe sexual reproduction of fungi
Introduces genetic variation
Occurs when nutrients are limited or other unfavourable conditions are present
Mating types are designated as + and -
Fungal spores are compact and lightweight
Can be dispersed widely throughout the environment by air, water, other organisms
Name some women with historical influence on STEM
Mary anning: paléontologist in 1800s who found and described many species and introduced extinction but got no credit
Mary Tharp: earth scientist in 1940s who discovered sea floor spreading but dismissed as Girl talk
Rosalind franklin
What is the most common type of infection?
Respiratory infection
Why is the respiratory system prone to infection?
Circulate a lot of air and huge surface area in lungs
In many parts, only a single celles layer separates the external environment from internal
Over 200 types of viruses that can cause common cold alone
What are the three main parts of the respiratory system?
Airway, lungs, and respiratory muscles More specifically: - external nose - nasal cavity - pharynx, larynx, and trachea - bronchi/bronchioles - lungs - diaphragm and respiratory muscles
What are alveoli?
Thin/hallow cavities that are the site of gas exchange in the lungs
What criteria must be met for an infection to be caused an exogenous agent?
- Sufficient number (dose) of infectious agents (airborne or contained in droplet) must be inhaled
- Must remain alive and viable in air
- Organism must find susceptible tissue for attachment/growth
- Once in respiratory tract, must colonize in surface before it can cause disease
What are the most common bacteria found in the normal flora of the upper respiratory tract?
Staphylococcus aureus and S. Epidermidis
What is the défense mechanism of the lungs?
Mucous in lungs
Cilia beat upwards clearing mucous and produce new mucous
What are fomites?
Anything that could harbour infectious agents
How does the respiratory tract get infected?
Damage to the mucosal lining allows bacteria in normal flora to become infectious
Damaged by smoking, dryness, she pollution, laryngitis, allergies
Often viral infections cause damage allowing bacterial species in for secondary
What are most respiratory infections?
90% of acute and 50% of lower respiratory infections are primarily caused by viruses
Describe the common cold
Viral infection of the upper respiratory tract that primarily effects the nose and nasal cavity Most frequent human disease Rhinoviruses are the leading cause 3-5 days Highly contagious and opportunistic No specific treatment
Describe the influenza virus
An infectious viral disease caused by influenza virus
Caused by orthomyxoviruses - group V meg ssRNA viruses
Person to person or by fomites
Cause complications; secondary infections, worsening of chronic conditions such as asthma or congestive heart failure
What are the three genera of influenza?
Influenza A: infects humans, other mammals, birds, and causes all fly pandemics
- cause most severe disease state
Influenza B: infects humans and seals
Influenza C: humans, pigs and dogs
What are the symptoms of influenza?
Fever, headache, fatigue, dry cough, sore throat, rhinitis, myalgia
Gastro-intestinal symptoms (sometimes) - more common in children then adults
Describe the progression of influenza
5-6 days after contact, symptoms appear
Contagious about a day before symptoms to a week after
Initial symptoms are fever, headache, aches, muscle pains, fatigue
Moves into upper respiratory tract and develop sore threat then stuffy nose, sneezing, and dry cough (around 3 days)
Describe viral pneumonia
Pneumonia: severe inflammation of the lungs, specifically alveoli
About half caused by viruses
Causes fevers, nonproductive cough, rhinitis, myalgia, headache
Most cases are mild, severe forms. Ah require hospitalization and be treated with antivirale and humidified air
Describe hantavirus pulmonary syndrome (HPS)
Deadly disease caused by hantaviruses
Carried by rodents - transmission through contact with infected animals, their waste
Begins with childlike symptoms, and progress to acute respiratory stress syndrome
Fatalities in 30 to 40% of cases
Describe SARS
Zoonotic
In 2006, genetic link between human SARS and féline SARS found
Person to person transmission via drop
Can be life threatening, especially in vulnerable populations
High fever, headache, body aches, dry cough, followed by pneumonia
Treatment includes antipyretics, supplemental oxygen, additional ventilator support
Describe the 2002 SARS outbreak
Seems to have originated in mainland China
Spread worldwide for several months before curtailed by help from WHO
Reported to have mortality rate of 9.5%
Symptoms appear 2-10 days but mostly with 2-3 days and 10-20% need ventilation
Describe streptococcal pharyngitis (strep throat)
Caused by group A streptococcus - specifically streptococcus pyogènes
Most common bacterial infection of the throat
Most common in children
Affects back of throat, uvula and tonsils
White or red spots, inflammation
Describe scarlet fever
Group A beta-hemolytic streptococci; S.psyogens
Begins with fever and sore throat, night also exhibit chills, vomiting, abdominal pain
Strawberry tongue due to erythrogenic exotoxin that damage capillaries under the skin - causing the red rash
Describe streptococcus pneumonia
Gram positive, encapsulated alpha-hemolytic diplococcus
Can be found in resident flora
Common cause of mild respiratory illness
Main cause of community acquired pneumonia and meningitis in children and the elderly
How do you treat pneumococcal pneumonia?
Since 2007, resistant strains have become common
Mechanism of resistance to penicillin and cephalosporins is through alteration of cell wall targets, penicillin-binding proteins (PBPs)
Can be overcome if the antibiotic concentration at the site of infection exceeds the MIC of the organism for 40-50% of the dosing interval
Describe mycoplasma pneumoniae
Small bacteria that lacks a cell wall
Hospitalizes 6509 people per year in Canada
Primary atypical/uncomplicated pneumonia - relatively mild
Usually affects people younger than 40
Usually due to crowded areas
Describe chlamydophima pneumonia
One of the major causes of pneumonia or bronchitis
Transmission by respiratory secretions
Most common in school age children
Community acquired pneumonia - easily passed from one individual to another
Describe pertussis
Highly contagious
Caused by Bordetella pertussis - small, aerobic, gras-negative coccobacillus
Slow incubation, begins with cold-like symptoms and leads to severe coughing spells 10-12 days, can last 4-6 weeks, can lead to vomiting
Can cause permanent disability or death
Person to person via droplets
Vaccine available but not widespread
Describe TB
Caused by mycobacterium tuberculosis
Airborne
Infected persons may not show symptoms but may have latent tb
Fever, night sweats, loss of appetite
Some may go into remission or become chronic and debilitating
Transmission prevented by vaccine and antibiotics
Describe histoplasmosis
Contracted from soil, manure, farms caved
Describe coccodiodomycosis
Found in southern US to South America
Désert soil, rodent burrows, archaeological remains, mines
Describe blastomycosis
- Flu-like, often resolved in 2-3 days
- Acute symptoms similar to bacterial pneumonia, including high fever, chills, a productive cough (brown, bloody), chest pain
- Chronic - resembling tuberculosis or lung cancer, symptoms include low fever, productive cough, night sweats, and weight loss
- An aggressive and sever disease that causes ARDS, a life threatening condition that causes lung swelling and fluid buildup in the air sacs
Describe aspergillosis
Generally mild, may lead to secondary pulmonary arpergillosis
