Algae
Diverse group of eukaryotic organisms
Use light to convert carbon dioxide and water to carbohydrates
Includes both microscopic unicellular and macroscopic multicellular organisms
Algae
Classification of algae Algae not a distinct classification term Grouped for identification based on numerous
properties Photosynthetic pigments Cell wall structure Type of storage products Mechanism of motility Mode of replication
Names are derived from major color displayed by group
Algal habitats Found in both fresh and salt water and soil Aquatic algae major producers of oxygen
Also important users of carbon dioxide Algae often grow where other life forms can’t
Often first to become established in barren environments
Algae
Structure of algae Can be both micro and macroscopic Can float free or be propelled by flagella or
filaments Macroscopic algae are multicellular
Contain numerous structures for specific functions
Holdfast anchors organism to firm substrate Stapes hold blades which are the major
photosynthetic portion of algae Gas-containing bladders to help maintain blades in
proper position for maximum sunlight
Algae
Algae
Structure of algae Cell wall
Rigid structure made mostly of cellulose
Diatoms have silicon dioxide incorporated in cell wall
Cell structures Have membrane bound nucleus
containing DNA Have both chloroplast and
mitochondria Chloroplast for photosynthesis Mitochondria for respiration
Algae
Algae reproduction Most single cell algae
reproduce through binary fission
Chromosome goes through mitosis
Some algae reproduce through fragmentation
Portion of parent organism breaks off to form new organism
Sexual reproduction through meiosis also occurs
Algae Algae do not cause disease
directly Numerous algae produce toxin
Toxins are poisonous to humans
Some species such as dinoflagellates produce neurotoxins
Dinoflagellates eaten by shellfish and produce toxin
Toxin accumulates in shellfish tissues
Human eat shellfish and suffer paralytic shellfish poisoning
Protozoa
Microscopic unicellular organisms
Lack photosynthetic capability
Usually motile Reproduce by asexual
fission
Classification of protozoa Not a unified group
Lumped together as unicellular organism lacking chlorophyll
Traditionally divided into groups based on mode of locomotion
Some belong to phylum Sarcomastigophora Includes two subphyla
Mastigophora Sarcodina
Protozoa
Protozoa
Classification of protozoa Mastigophora
Includes flagellated protozoa Most significant include
Giardia lamblia, Leshmania species Trichomonas vaginalis and Trypanosoma species
Sarcodina Move by means of pseudopodia Entamoeba hystolytica produces disease in
humans
Classification of protozoa Other phylum include
Ciliophora Organism have cilia Balantidium coli only pathogenic ciliate
Apicomplexa Cause most serious protozoan disease
Plasmodium species causes malaria Microspora
Cause sever infection in immunocompromised
Protozoa
Protozoa
Protozoan habitats Majority are free-living
Found in marine, fresh water and terrestrial habitats Essential decomposers Require large amounts of moisture Important part of food chain
Protozoa eat bacteria and serve as food for larger species
Help maintain ecological balance in soil Important in sewage disposal
Results in decrease of sewage solids
Protozoa
Structure of protozoa Cell wall
Lack cell wall Shape determined by material beneath plasma
membrane Cell structures
Have membrane bound nucleus and organelles Lack photosynthetic chloroplasts
Have specialized structures for movement Cilia, flagella or pseudopodia
Protozoa grouped by mode of locomotion
Protozoa
Protozoan reproduction Life cycles complex
Often require more than one habitat or host
Polymorphic Can exist as trophozoite or as
cyst Both sexual and sexual
reproduction common Many replicate via binary fission Many replicate by schizogony
Many fissions Nucleus divides numerous times
then cell produces numerous single celled organisms
Fungi
Describes a taxonomic classification of organisms No longer includes slime molds and water molds
Fungi require organic compounds for energy and as a carbon source
Most are aerobic or facultative anaerobe Large number of fungi cause disease in plants
Only a few cause disease in humans
Classification of fungi Can be both micro and macroscopic Cell wall consist of chitin No flagellated cells Four groups of true fungi
Zygomycetes Basidiomycetes Ascomycetes Deuteroomycetes
A.k.a fungi imperfecta
Classification in groups based on sexual reproduction Except d where sexual reproduction is not seen
Fungi
Classification of fungi Zygomycetes
Includes common bread mold Rhizopus Ascomycetes
Includes the fungi of Dutch elm disease Basidiomycetes
Includes common mushroom and puffballs Deuteromycetes
Includes medically and commercially important species including the penicillium
Fungi
Fungi Classification of fungi
Grouping of fungal forms Yeasts
Single celled fungi Spherical, oval or cylindrical Reproduction through binary fission or budding
Molds Filamentous fungi contain hyphae collection of hyphae called mycelium Reproductive spore is single celled germinates to develop hyphae cells
divide into new form Dimorphic fungi
Can grow as yeast or mold depending on environment Many pathogenic fungi are dimorphic
Fungi
Fungal habitats Found in virtually every
habitat Mainly terrestrial
Fungal spores found throughout the earth
Uncountable numbers found in air
Major cause of asthma
Growth requirements of fungi Slightly moist environment
with high humidity 70% or higher
pH range varies Most grow well in
slightly acidic environment
Most are aerobic Some yeast facultative Some fungi obligate
anaerobes
Fungi
Fungal diseases in humans Cause disease in one of four ways
Allergic reaction Result from inhaling fungal spores
React to fungal toxin Many have hallucinogenic properties Certain species produces alflatoxin implicated in cancer
Mycoses Fungi grows on or in the body
Economic impact Destroy human food supply causing starvation
Fungi Symbiotic relationships of fungi
Form several symbiotic relationships with other organisms
Lichens result from relationship between fungi and photosynthetic organism
Relationships are very close Fungus provides protection and
growing platform Other organism supplies nutrient
Mycorrhizae symbiosis with roots of plants
Increases absorptive property of roots
Allow plant partners to grow in dryer climates
Fungi
Economic importance of fungi Many are important commercially
Saccharomyces used in production of beer, wine and bread
Many important for cheese production Penicillin, griseofulvin as well as other antimicrobials
are made from fungi Elimination of disease causing fungi from
commercial crops vitally important Fungi used in genetic and biochemical studies
Yeast genetically engineered to produce human insulin
Slime Molds and Water Molds
Used to be considered types of fungi They are completely unrelated Good example of convergent evolution
Two organisms develop similar characteristics and adaptations but not related on molecular level
Slime Molds and Water Molds Acellular slime molds
Terrestrial organisms Non motile Reproduction depends of formation of
dispersible spores Acellular slime molds readily visible in
environment Plasmodium formed from nucleus
spreads over surface of decaying matter
Cellular slime molds Has vegetative form made of ameba-
like cells Single cells congregate into form
called slug Slug forms fruiting body and spores
Slime Molds and Water Molds
Water molds A.k.a Oomycetes Members of heterokonts Do not have chlorophyll Once considered fungi
Due to morphology Form masses of white thread on decaying
matter Zoospores cause serious disease of food
crops
Multicellular Parasites:Arthropods and Helminths
Arthropods include Insects such as
mosquitoes responsible for transmission of malaria and fleas which transmits plague
Ticks responsible for transmission of Rocky Mountain Spotted Fever and Lyme disease
Lice responsible for transmission of typhus and other fevers
Mites transmit scabies
Helminths include nematodes, cestodes and tremetodes Cause disease by
invading host tissues and robbing nutrients
Nematodes invade gastrointestinal tract and blood stream
Cestodes associated with meats especially pork
Transmission results from consumption of uncooked meat
Trematodes Can be found discharged
in waters such as lakes and ponds