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HTHSCI 2C06 Study Guide - Midterm Guide: Mitosis, Aztreonam, Endocarditis

Health Sciences
Course Code
Ruth Hannon
Study Guide

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2C06 - Pathophysiology - ‘Super 7’ Lists
Week 1 - Microbiology
1. Basic differences in bacteria, mycoplasma, chlamydia, fungi, and parasites
The agents of infectious diseases include prions, viruses, bacteria, rickets, chlamydia, fungi and parasites.
These microorganisms can be separated into eukaryotes (fungi and parasites), organisms containing a
membrane-bound nucleus, and prokaryotes (bacteria), organisms in which nucleus is not separates
Eukaryotes and Prokaryotes are organisms because they contain all the enzymes and biologic equipment
necessary for replication and exploiting metabolic energy
Viruses [which are the smallest pathogens], have NO organized cellular structure, but consist of a protein
coat surrounding a nucleic acid core of DNA or RNA. Unlike eukaryotes and prokaryotes, viruses are
incapable of replication outside of a living cell.
Parasite [protozoa, helminths, and arthropods) are members of the animal kingdom that infect or
colonize other animals, which then transmit them to humans or in some cases directly infect the human
Bacteria: No defined Nucleus, has a genomic material known as DNA, Intracellular and + Motility
o Unicellular
o Prokaryotes due to lack of a nucleus
o Bacterial cell is small, primitive
o Similar to eukaryotic cells, but unlike viruses, bacteria contain DNA and RNA
o No organized intracellular organelles
o Genome consists of only single chromosome of DNA
o Prokaryotic cell is organized into an internal compartment called cytoplasm (reproductive
and metabolic machinery of the cell)
o Cytoplasm surrounded by a flexible lipid membrane called cytoplasmic membrane
o Motile; external whip-like appendages called flagella
o when cocci divide into chains, it is called streptococci; in pairs diplococci and in clusters
o bacteria stick to and colonizes environmental surfaces, structured communities such as
§ biofilms access to nutrients and elimination of metabolic wastes
§ Growth Parameters of Bacteria:
· Nutrition, temperature, light, humidity, atmosphere
· Bacteria (gram-positive organism) if they are stained purple by a primary
basic dye
o Spirochetes
§ Bacteria unusual cellular morphology and mechanism of motility
§ Gram-negative rods but are unique in that the cell’s shape is helical and length of
the organism is many x the width
§ Corkscrew motion via filament propelling the organism
§ Anaerobic organisms

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§ Saprophytic and pathogenic strains
§ 3 genera;
· Leptospira, Borrelia, Treponema
§ Pathogenic;
· Wild and domestic animal infection and sheds organisms via urinary
· From these animals to humans via contact with the infected animal and
urine surroundings
· Borrelia transmitted through infected animals through the bite such as
lice/ ticks
· Treponema spread from person to person via direct contact
o Syphilis (treponema pallidum) most important member of the
Mycoplasmas: No defined nucleus, had genomic material DNA, Extracellular and – Motility
- Unicellular prokaryotes capable of independent replication
- Less than 1/3 size of bacteria
- Small DNA genome approximately one half the size of bacterial chromosome
- Does NOT produce a rigid peptidoglycan cell wall unlike bacteria
- Appearance highly variable, coccoid forms to filaments and are resistant to cell- wall inhibiting
antibiotics like penicillin + cephalosporins
o The Mycoplasmas that affect humans are divided into 3 genera:
· Mycoplasma, ureaplasma, acheloplasma
§ In the human HOST- the mycoplasmas are commensals
§ # of species are capable of producing serious diseases such as pneumonia
(mycoplasma pneumonia) genital and maternally transmitted respiratory
infections in infants with low birth weight (U. urealyticum)
Chlamydia: No defined nucleus, has genomic material DNA, Intracellular and – Motility
o Adenosine triphosphate (ATP)
o Infectious form called elementary body- attaches to and enters the host cell where it
transforms into a larger reticulate body
o STD’s, ocular infections and pneumonia of newborns, upper and lower respiratory tract
infections in kids, teens, and young adults and resp diseases acquired from infected birds
(chlamydia psittaci)
Fungi: Free living, eukaryotic saprophytes found in every habitat on earth
- Some are members of the normal human microflora
- Few flora are capable of causing diseases in humans and most of them are incidental self limited
infections of skin and s/c tissue
- Cause life threatening opportunistic diseases when host defence capabilities have been disabled
- 2 groups:
o Yeasts & Moulds
- Yeasts:
§ Single celled organisms, size of RBC produce by budding process
§ Separate from parent cell and mature into daughter cells
- Moulds:

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§ Produce long, hollow branching filaments called hyphae
o Colonies of yeast are smooth with waxy/creamy texture
o Moulds tend to produce powdery/cottony colonies composed of mats of hyphae called
o Both yeasts/ moulds produce rigid cell wall layer chemically unrelated to the
peptidoglycan of bacteria and not susceptible to effects of penicillin-like antibiotics
- Most fungi are capable of sexual or asexual reproduction
o Fusion of zygotes with production of zygospore
o Asexual involves formation of resistant spores called conidia or sporangiospores
- Moulds, identified in the lab by microscopic appearance of the asexual fruiting structures and spores
- Bacterial pathogens of humans, fungi can produce disease and human host if they can grow at the temp
of the infected body site
- Yeasts such as candida albicans are commensal flora of the skin, mucus membranes and GI tract that are
capable of growth at a wider range of temperatures
- Alterations in either the intact immune system or by disease states/antibiotic therapy can upset normal
flora balance permitting fungal overgrowth and setting stage for opportunistic infections
Parasites- any organism that derives benefits from its biologic relationship with another organism is a
o protozoa, helminthes and arthropods
o Protozoa—unicellular animals with complete complement of eukaryotic cellular
machinery, well defined nucleus and organelles
§ Reproduction- asexual or sexual and life cycles can be simple or complicated
§ Most are Saprophytes but a few have adapted to human environments
§ Produces a variety of diseases including
· Malaria
· Amoebic dysentery
· Giardiasis
§ Protozoan infections- from host to host including 1. Sexual contact 2. Indirectly
through contaminated water/food 3. Arthropod vector
§ Direct/indirect transmission= ingestion of resistant spores shed in the feces of an
infected host
§ Parasitic arthropods of humans and animals include the vectors of infectious
diseases [ticks, mosquitoes, biting flies] and ectoparasites
· Most prominent ectoparasites are mites/scabies, chiggers, lice, and fleas
· Transmission—directly by contact with immature/mature forms of
arthropod or its eggs on the infested host or the clothing/bedding or
2. Characteristics and main functions of the normal flora
- Can be opportunistic pathogens capable of producing an infectious disease when the health and
immunity of the host has been severely weakened by illness, malnutrition or medical therapy
- Not all interactions between microorganisms and humans are detrimental
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