Biosci 221 - Exam 1

Chapter 1, Protists (algae and protozoa), fungi. and helminths

Bacteria

cells lacking a nucleus

Archaea

nonbacterial cells that lack a nucleus

Protists

mostly unicellular eukaryotes

Fungi

chemoheterotrophic organisms that are usually nonmotile and grow by absorbing nutrients from their surroundings

Helminths

parasitic worms that are multicellular, eukaryotic, invertebrate animals, most are macroscopic but have microscopic life stages

Viruses

noncellular microbes that must infect a host cell

One or 2 sentences regarding any of the scientists included in the Ppt.

* Robert Hooke built the compound microscope and thus the first to observe cells
* Antonie van Leeuwenhoek was the first to observe single-cell microbes (bacteria and protists), documenting their size and shape for identification with a single lens microscope

One or 2 paragraphs worth of info about Louis Pasteur and Robert Koch

* Louis Pasteur discovered:
* Discovered fermentation was caused by a single-celled, living yeast
* Developed the “swan-neck” flask that kept boiled contents free from microbes and used this flask to show that even without oxygen microbes can grow (disproving spontaneous generation)
* Was the first to recognize that attenuated strains of a microbe could still confer immunity to the disease. He learned that certain microbes required different treatments in order to be attenuated which led to his rabies vaccine.
* Robert Koch:
* Germ theory (specific microbe causes specific disease)
* Chain of infection (spread of disease; the infectious agent, source of infection, portal of exit, mode of transmission, portable entry, and susceptible host)
* devised techniques of __pure culture__ to study a single species of microbe in isolation
* Koch’s postulates

Koch's Postulates

four criteria designed to establish a causal relationship between a causative microbe and a disease

Postulate 1

The microbe is found in all cases of the disease but is absent in healthy individuals. 

Postulate 2

The microbe is isolated from the diseased host and grown in pure culture. 

Postulate 3

When the microbe is introduced into a healthy, susceptible host, the same disease occurs.

Postulate 4

The same strain of microbe is obtained from the newly diseased host.  

Importance of microbes to the Earth and people

Microbes act as decomposers, degrading biological waste and helping keep the environment clean

Some do nitrogen fixation, helping plants absorb nitrogen from the soil

Some do photosynthesis giving us oxygen 

Some can be used in meds like penicillin

Microbes also live in our bodies; i.e. good gut bacteria protect against infection by pathogens and help digestive processes

Types of scientists or fields of study in microbiology

agricultural microbiology (managing plant pathogens and plant-associated microbes) and forensic microbiology (analyzing microbial strains as evidence in criminal investigations)

Taxonomy

An ordered group of ranks used to classify organisms from general to specific (Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species)

Binomial nomenclature

Formal naming system for living things that all scientists use

How do you properly write scientific names?

The genus name is capitalized and the species is lowercase, italicized or underlined if you can't italicize; the abbreviated first letter of the genus is capitalized and the full name of the species is in lowercase (can only be abbreviated after it has already been written fully)

History of microbes on Earth

Hydrothermal vents in the ocean?

Some of the organelles in eukaryotic cells were once prokaryotic microbes; the larger cell engulfed or took in the smaller cell.

Endosymbiosis

A condition of living within the body or cells of another organism; explains the origin of mitochondria and chloroplasts

Prokaryotic cells versus Eukaryotic cells

cells that lack a nuclear membrane and have no membrane-bound organelles are called prokaryotes while eukaryotes are cells with a nucleus

Algae

photoautotrophic, usually have a cell wall

Protozoa

chemoheterotrophic, no cell wall but have a pellicle

What is the difference between algae and protozoa?

protozoa must find and ingest their food from their environment, while algae are photosynthetic and can make their own food

Chemoheterotroph

Carbon source = organic

Energy source = chemical breakdown of carbon source

Photoautotroph

Carbon source = inorganic

Energy source = sunlight

Paralytic Shellfish Poisoning (PSP)

caused by *Alexandrium*

eating shellfish that contain these toxins can cause paralysis

Diatoms

eukaryotic single-celled algae

Dinoflagellates

eukaryotic group of single-celled algae

“red tide” gives off toxins

Harmful Algal Blooms (HABs)

when colonies of algae grow out of control and produce toxic or harmful effects on the environment

**two** of the important uses of algae

Spent biomass can be used as fertilizer

Its bioactive compounds can be used in pharmaceuticals

*Entamoeba histolytica* (life cycle)

1. ingested
2. undergo schizogony and excyst in small intestine
3. binary fission
4. encyst in large intestine
5. cysts exit in feces

*Giardia* (life cycle)

1. ingested
2. undergo plasmotomy and excyst in small intestine
3. binary fission
4. encyst near colon
5. cysts exit in feces

*Plasmodium* (life cycle)

(see picture)

*Trichomonas*

STI

does not form cysts

can be asymptomatic

*Giardia*

Diarrheal disease

cysts can survive hours in the pool

1-10 billion cysts released daily

infective dose approximately 10 cysts (low)

*Trypanosoma cruzi*

Chagas’ disease

a neglected disease

vector = a reduviid bug bite

largest cause of preventable heart disease in the world

*Leishmania*

A neglected disease

vector = sand fly

3 different forms (cutaneous, mucocutaneous, and visceral)

*Naegleria fowleri*

This free-living protist gets into your sinuses

100% fatality

*Acanthamoeba*

Free-living amoeba which causes keratitis (corneal infection)

is caused by cleaning contacts with water

*Entamoeba histolytica*

Diarrheal disease

a very common protist infection worldwide

usually taken care of by water treatment

*Toxoplasma gondii*

Foodborne

congenital transmission (organisms cross the placenta)

potential inhalation of dried cysts

*Plasmodium*

Malaria

Vector = mosquito

*Cryptosporidium*

Diarrheal disease

fecal-oral route of transmission

can survive in the pool

cause of the largest waterborne outbreak in the U.S. (Milwaukee)

Mycoses

fungal infections which can be caused by inhalation or contact with asexual spores

True pathogens

can cause disease in any susceptible host

Opportunistic pathogens

rarely cause disease in healthy individuals

Concerns about mycoses

Difficult to treat as there are a limited number (14) of antifungal agents known, most of which are relatively toxic

Is a frequent cause of **HAI**s, or healthcare-associated infections

Hard to develop a medication that could harm the fungal cell but not our cell b/c both cells are eukaryotic

*Aspergillus flavus*

Produces **Aflatoxin B** (the most potent carcinogen known)

can infect crops, lethal to poultry and livestock

*Aspergillus fumatigus*

Farmer’s Lung

opportunistic pathogen

associated with people working outside in fields and agriculture

*Cryptococcus neoformans* and *C. gatti*

Neoformans are opportunistic while gatti is emerging

found in pigeon and chicken droppings and can therefore be found in the soil

the leading cause of death in AIDs patients in Africa

*Candida albicans*

Candidal intertrigo, candida thrush, candida meningitis

most common fungal HAI

50% fatality rate

*Candida auris*

Urgent threat

highly antibiotic-resistant that has spread quickly around the world (and in healthcare settings)

*Coccidioides immitis*

Valley Fever

is a true pathogen

endemic (regularly occurring) in the U.S.

windy conditions help spread its fungal spores

often misdiagnosed

hardly reportable

*Histoplasma capsulatum*

Spelunkers disease

a true pathogen

grows in humid, high nitrogen areas where there is bird and bat guano

endemic in the U.S.

not reportable in CA

often misdiagnosed

*Blastomyces*

A true pathogen

acquired from the environment (inhalation) not person to person hardly reportable

*Sporothrix*

Cause of sporotrichosis (rose gardener’s disease)

from getting poked or scratched

*Trichophyton*

Trichophyton is a dermatophytic fungus, which is often responsible for nail, hair follicle, and superficial skin infections (i.e. Tinea pedis is athlete’s foot)

Dr. George Washington Carver

* Documented fungal diseases of plants
* He sent over 1000 fungi to the U.S National Fungus Collection
* This was essential in identifying fungi occurring in the U.S. to develop control measures such as breeding for the resistance to the diseases of the crops

*Pneumocystis*

* Small, unicellular fungi that cause pneumonia (PCP)
* Forms secretions in the lungs that block breathing
* Opportunistic infection and used to be the leading cause of death in AID patients

*Stachybotris*

Sick building syndrome

“toxic black mold” found in water-damaged structures

*Claviceps purpurea*

* Ergot
* Plant pathogen (that grows on rye) that is responsible for significant toxic poisonings throughout history
* I.e. St. Anthony’s Fire — killed 1000s in the Middle Ages
* Now used in many meds as a vasoconstrictor

Parasitic Helminths…

have a high rate of reproduction,

are usually host-specific

usually does not kill the host

have different methods to evade the immune system

Class Trematoda

flukes

leaf-shaped

mollusks are usually the intermediate host(s)

the vertebrate is usually the definitive host

digestive system

Class Cestoda

tapeworms

long/ribbon-like bodies

scolex for attachment (with reproductive segments called proglottids)

usually also require two or more hosts

no digestive system

Phylum Nematoda (roundworms)

cylindrical

usually only one host

complete digestive system

very diverse and numerous group

Intermediate (or Secondary) host

the host in which larval development occurs

Definitive (or Primary) host

the host in which mature organisms live and undergo sexual reproduction

*Clonorchis sinensis*

Chinese liver fluke

from consuming fresh water fish

*Schistosoma*

Blood fluke

neglected disease

burrows into the skin

snail is intermediate host

Cercarial dermititis

Swimmer’s Itch (bad rash)

*Taenia solium ** (and Cysticercosis)

Found in uncooked/undercooked pork

fecal/oral route

leading cause of epilepsy in the world

*Ascaris lumbricoides*

Ingested

fecal/oral route

invasive

most common helminth infection in the world

*Necator americanus*

Hookwork (has cutting mouthparts)

burrows through the skin (in between the toes)

blood in stool and anemia

*Enterobius vermicularis*

Pinworm

the most common infection in the U.S.

passes through fecal/oral route so its hard to control

*Trichinella spiralisis*

from eating contaminated/undercooked pork

less common now b/c of regulations (can’t feed pigs trash)

most common in area where people eat wild game