Intro To Eukaryotic Organisms Flashcards
What are some identifying characteristics of eukaryotes?
- Have a membrane surrounding their DNA
- Have a nucleus
- Have internal-membrane bound organelles
- Are larger, 10-100 um in diameter
- Have more complex structure
What organisms are eukaryotes?
Algae, fungi, Protozoa , animals, plants
What are the eukaryotic appendages?
Flagella
Cilia
What is the difference between the rough and smooth Endoplasmic Reticulum?
Rough: associated with ribosomes; makes secretary and membrane proteins
Smooth: makes lipids
What are the components of the cytoskeleton?
Microtubules
Intermediate filaments
Microfilaments
Centrosome(kinda)
What is the function of microtubules?
Form the mitotic spindle and maintain cell shape
What is the function of the centrosome?
Microtubules organizing center
What is the function of the intermediate filaments ?
Fibrous proteins that hold organelles in place
What are the functions of microfilaments?
Fibrous proteins; form the cellular cortex
What is the function of the Nucleolus?
Enclosed region where ribosomes are formed
Describe the eukaryotic flagella
Long appendages present singly or in bundles that propel the cell with a whip-like motion
What is the flagella composed of?
Composed of tubulars and microtubules
Describe the Cilia of eukaryotes
Similar to flagella in structure and function, but cilia are much smaller and more numerous
Cilia move in an undulating manner
Cilia are found __________ to the cell
Peritrichously
Which organism would move faster between those with cilia or those with flagella?
The one with cilia
Where is chlorophyll found?
In chlorophyll containing organelles found in phototrophic eukaryotes- plants, unicellular and multicellular algae and protists
How do chloroplasts appear under a light microscope?
Relatively large and and readily visible with the light microscope
Describe briefly, the structure of chloroplasts
Composed of two phospholipid bilayer membranes and contain 70s ribosomes and DNA
What are thylakoids?
A flattened membrane disc containing all other components needed for photosynthesis
When did the first eukaryotic organism evolve?
Thought to evolve 1.5 billion years ago
What is endosymbiosis?
A process where one prokaryote lives inside the cell of another organism to the benefit of both
What is the endosymbiosis hypothesis?
Mitochondria and chloroplasts are thought to have evolved from bacteria that were engulfed by larger cells
What is primary endosymbiosis?
Involves the engulfment of a bacterium by another free-living organism
What is Secondary endosymbiosis?
Occurs when the product of primary symbiosis is engulfed and restrained by another free-living eukaryote.
Explain the result of secondary endosymbiosis
Secondary endosymbiosis has occurred several times and has given rise to extremely diverse groups of algae and other eukaryotes
How do organisms in the Kingdom: Protista reproduce?
Binary fission
Multiple fission
Sexually by contagion
What is binary fission?
Splits into two asexually
What is multiple fission?
Producing more than 2 individuals
How can protists be classified?
Into 2 major groups:
- plant-like
- animal-like
- fungi-like
In 11 phyla
Where are protists usually found ?
In aquatic environment, some are terrestrial while others can be present in a suitable host
What sizes are Protista?
Mostly unicellular, microscopic or macroscopic.
How do protists acquire nutrients?
These are a heterogenous groups that include, heterotrophic, photoautotrophic or a combination of both forms
What are examples oof animal-like protists?
- Sarcodinia
- Ciliophoria
- Zooflagellates
- Leishmaniasis
- Sporozoa
- Malaria
Describe Sarcodinia
Free-living animals-like protists that inhabit aquatic and soul environments
They utilize pseudopodia for locomotion, feed by phagocytosis on bacteria, other protists, and organic materials
What are entamoebas?
- Parasites of vertebrates and invertebrates
- Forms cysts that are transmitted from person to person
Give examples of entamoebas
E.g. entamoeba histolytica -amoebic dysentery
E.g. Naegleria spp. - primary amoebic meningoencephalitis
Describe Ciliophoa
- Complex and unicellular animal-like protists
- utilize cilia for locomotion
- defined shape and 2 nuclei
- some associated with diseases in humans
How does Ciliophora reproduce?
Reproduce asexually by binary fission and sexually by conjugation
Give a general description of zooflagellates
- Lack plastids
- Reduced mitochondria(often anaerobic)
- lack key enzymes
List the types of zooflagellates
- Diplomonads
- Parabasalids
- Euglenoids
- Kinetoplastids
Describe Diplomonads
- a type of zooflagellate
- 2 nuclei
- Multiple flagella
- E.g. Giardia-intestinal giardiasis
Describe Parabasalids
- a type of zooflagellates
- Flagella and undulating membrane
- May have genes from bacteria
- e.g. trichomonas-sexually transmitted
Describe Euglenoids
- a type of Zooflagellates
- Characterized by anterior pocket with 1 or 2 flagella
- Autotrophic, mixotrophic or heterotrophic
- e.g. Euglena
Describe Kinetoplastids
- a type of zooflagellates
- 1 flagella
- Single large mitochondria associated Kinetoplast
Give examples of diseases caused by kinetoplastoids
Trypanosoma-African trypanosomiasis
American trypanosomiasis
Leishmania organism which causes leishmania
Describe the structure of sporozoa
- Possess “apical complex” consisting of microtubules and other components that is used to infect host cell
- Have apicoplast(non-photosynthetic plastid)
Describe the pathogenicity of Sporozoa
- Parasites of animals and humans and some cause serious disease
- multiple life stages, reproduce asexually and sexually
- vector transmitted, require 2 or more different host
Give examples of Sporozoa
Plasmodium, Cryptosporidium and toxoplasma
Describe Malaria infection
- Malaria infection
- Stages in liver
- Stages in red blood cells
- Certain merozoites develop into gametocytes
- Gametocytes ingested by mosquito
- Sporizoites form within mosquito
What is the causative agent of Malaria?
Plasmodium spp.
What transmits Malaria?
Mosquito, Anpheles spp.
Describe the life cycle of Plasmodium spp. / malaria
Complex life cycle involving asexual (vertebrate host) and sexual (mosquito) reproduction
How does Malaria affect the world?
Associated with high morbidity and mortality worldwide
Who does Malaria infect?
Infects vertebrate hosts, including, humans
Describe the life cycle of Chlorophyta
Complex life cycle involving sexual and asexual stages
Describe the variations of chlorophyta
Microscopic or macroscopic, unicellular or multicellular, motile or non-motile
Describe the structure of chlorophyta
- contain beta carotene and xanthophylls in addition to chlorophyll A and B
- cell wall contains cellulose and store food from starch
- similar to plants
Where is green algae usually found?
Mostly found in freshwater, some marine or soil, or symboints.
Endolithic algae found in layers near rock surfaces
What is Chlorophyta ?
A division of lower plants that comprises the green algae
List 2 plant-like protists
- green algae
- red algae
What is Rhodophyta?
A division of lower plants that contains the red algae
Describe the structure of Rhodophyta/red algae
- Contain phycoerythrin and phycocyanin in addition to chlorophyll A
- Double cell walls- the outer layers contain the polysaccharides agarose and agaropectin that can be extracted from the cell walls by boiling
Where are Rhodophyta usually found?
Most abundant in coastal warm waters in tropical oceans or freshwater
Give examples of Rhodophyta
Agar(Gelidium), alginates (var. sources), carrageenan (Chondrus)
Describe the rhodophyta life cycle
-eukaryotic, mostly multicellular, reproduce sexually as well as asexually
Give examples of fungus-like protists
- water molds “egg fungus”
- cellular slime methods
Describe the structure of water molds “egg fungus”
- Fungus like morphology but not related to fungi
- cell wall contains cellulose and not chitin
How do water molds reproduce?
Reproduce sexually and asexually
What is the official name for “egg fungus”?
Water molds
Describe water molds “egg fungus” in the environment
Non-photosynthetic and include many saprobes and parasites and appear as white fluffy growths one dead organisms
Describe Cellular slime molds
-Individual haploid cells and form diploid only under certain conditions
Describe cellular slime molds in the environment
- ingest bacteria by phagocytosis
- cells aggregate to form a multicellular pseudopodium from which arise fruiting body
- some cells become spores
What kingdom are fungi in?
Mycetae
How many species of fungi are there?
100,000 species
How can fungi be categorized?
Microscopic fungi
Macroscopic fungi:
Yeasts
Molds
Some are dimorphic (yeast like and filamentous forms exist)
Usually unicellular or colonial
Describe yeasts
- Round or oval shape
- Unique mode of asexual reproduction
- Some form psuedohyphae(false filaments)
Describe molds
- Long, threadlike cells
- Filaments arrangement(hyphae)
Give the general mechanism of fungal nutrition
- penetrates the substrates
- secretes enzymes
- breaks down the enzymes into small molecules
- absorbs the molecules
Fungal nutrition has large Importance in…
Medical and agricultural
Describe possibilities to fungal nutrition
Heterotropic
Acquire nutrients from substrates
Most fungi are saprobes
Can also be parasites
What are the functions of hyphae?
- Vegetative hyphae(mycelia)- visible mass of growth on the substrate surface; penetrates the substrate to digest and absorb nutrients
- reproductive(fertile) hyphae- from vegetative hyphae; responsible for the production of spores
How do most microscopic fungi grow?
In loose associations or colonies
Describe the appearance of microscopic yeast fungi
Soft, uniform texture and appearance
Describe the physical appearance of filamentous fungal colonies
Cottony, hairy, or velvety textures
What is mycelium?
The woven, intertwining mass of hyphae that makes up the body or colony of a mold
What are the organizational features of hyphae?
- Septa- divide the hyphae into segments(most fungi have septate hyphae)
- Nonseptate hyphae- one long, continuous, multinucleate
Describe fungal sexual reproduction
- increases genetic variation
- Majority of fungi produce sexual spores at some point
- Sexual reproduction involves fusion of haploid “+” and “-“ mating types
Give examples of fungi that asexually reproduce
- sporangiospores
- conidospores
Describe Conidiospores
- Also known as conidia
- Free spores
- Develop either by pinching off the tip of the fertile hypha or by segmentation of a vegetative hypha
Describe Sporangiospores
- formed by successive cleavages within the sporangium
- Sporangium attached to the sporangiophore
- released when the sporangium ruptures
Nearly all fungi are _______________ and don’t need _________
Free-living
Host
How does human infection by pathogenic fungi usually occur?
Usually via accidental contact
What types of pathogenic fungi are humans not resistant to?
- Primary pathogens.
2. Opportunistic pathogens
What are the benefits of fungi?
- Decomposing organic matter and returning essential minerals to the soil
- Mycorrhize increase the ability of plant roots to absorb water and nutrients.
- Production of antibiotics, alcohol, organic acids, vitamins, food flavorings
How do Mycoses/ fungi negatively impact humans?
Not just infections but also allergies, poisoning, agricultural damage
What are parasites?
An organism that lives on or in a host organism and gets its food from or at the expense of its host
Why do parasites not kill?
Parasites cannot grow and multiply without a host so they don’t kill their host but it can spread diseases and some can be fatal
How do parasites differ from predators?
Parasites are much smaller than their host and reproduce at a faster rate
What are the 3 classes of parasites that cause disease in humans?
- Protozoa
- helminths
- ectoparasites
What type of respiration do protozoan parasites typically use?
Usually facultatively anaerobic
How much species of protozoan parasites are there?
Estimated 100,000 species but approx. 25 are important to humans
Give a brief description of the anatomy and physiology of protozoan parasites
-unicellular, animal-like microbes, most have some form of motility
- physiologically simple
- Acquire nutrition via pino or phagocytosis or enter via specialized site/structure
Describe the life cycles of protozoan parasites
- Most reproduce by simple asexual cell division (binary fission) of the active feeding cell
- Many undergo formation of a cyst
- A few others (e.g., Plasmodium spp. ) have a complex life cycle that includes asexual and sexual phases
What is the entamoeba histolytica as a pathogen
Intestinal protozoan parasites
Entamoeba histolytica: uses psuedopodia for locomotion, May invade the colon and cause bloody diarrhea-amoeba dysentery.
Also causes amoebic liver abscess, reproduce asexually
What is the Balantidum coli as a pathogen?
Intestinal protozoan parasites
Ciliate protozoan that lives in the colon of pigs, humans and rodents and lead to colonic ulceration, reproduces asexually
What is the Giarda lamblia as a pathogen?
Intestinal protozoan parasites
Flagellate protozoan with world-wife distribution, lives in the small intestine and results in malabsorption, reproduces asexually
What is Cryptosporidium parvum as a pathogen?
Intestinal protozoal parasites
Non-motile protozoan, more prevelant in the immunicompromised patients, reproduces sexually and asexually
Describe Cyclospora cyatenensis as a pathogen
Intestinal protozoal parasites
Non-motile protozoan, parasites the small intestinal mucosa and may cause diarrhea for several weeks, reproduces sexually and asexually
Describe Trichomonas vaginalis as a pathogen
Trichomonas vaginalis: flagellate protozoan, sexually transmitted, reproduces asexually
Name the intestinal protozoan parasites
- entamoeba histolytica
- Balantidium coli
- Giarda lamblia
- Cryptosporidium parvum
- Cyclospora cyatenesis
- Trichomonas vaginalis
Name the extra-intestinal/Blood and tissue Protozoa
- plasmodium spp.
- leishmania spp.
- trypanosoma
- Toxoplasma gondii
Describe Plasmodium spp. as a pathogen
Non-motile parasite, causative agent of malaria, transmitted by Anopheles mosquito.
There are 4 species that infect humans: P. falciparum, P. Vivax, P. Ovale and P. malaria
Describe Leishmania spp. as a pathogen
Extra-intestinal/blood and tissue protozoan
Flagellate protozoan, transmitted by sand flies, can lead to visceral, cutaneous and mucocutaneous leishmanias
Describe Trypanosoma as a pathogen
Trypanosoma: flagellate protozoan cause
In Africa -sleeping sickness (transmitted by the Tsetse Fly)
South America- Chaga’s disease (transmitted by the Reduviid bug)
Describe Toxoplasma gondii as a pathogen
Extra-intestinal/blood and tissue Protozoa
Non-motile Protozoa, transmitted by the ingestion of oocytes from cat faeces.
Infection can lead to severe manifestations and is also a cause of neonatal toxoplasmosis
Describe the structure of Metazoan parasites
Eukaryotic, multicellular animals that have digestive, circulatory, nervous, excretory and reproductive systems
Has bilateral symmetry, head and tail, and tissue differentiation (endoderm, mesoderm and ectoderm)
Where do Metazoan parasites spend their lives?
Spend most of their lives in host
What is another name of Metazoan parasite?
Helminths
What is are the classifications of helminths?
Nemahelminths(roundworms)
Class- nematoda
Phatylhelminthes(flatworms)
Class Trematoda(flukes) Class Cestoda(tapeworms)
Give the general features of nematodes(round worms)
- They have cylindrical bodies and complete digestive tracts
- Body is covered with a cuticle. The oral opening may have hooks or suckers to attach to mucosal epithelium.
- There are separate male and female sexes which mate and produce eggs within the human host
- The worms, larvae or eggs may be diagnostic. Eggs typically have a characteristic shape, cell wall density and cap (“operculum”) on one or both ends
Describe Ascaris
Round work and intestinal nematodes
- found world-wide in conditions of poor hygiene
- causes eosinophilia
Describe Enterobinus
Pinworm and intestinal nematodes
-prevalent worldwide, found mainly in children
Describe Trichuris as a pathogen
Trichuris(whipworm)
- prevalent in warm, humid conditions
- Can cause diarrhea, rectal prolapse and Anaheim’s in heavily-infected people
Describe Ancylostoma and Necator as pathogens
Ancylostoma and Necator(hookworms)
A major cause of Anaemia in the tropics
Describe strongyloides as a pathogen
- inhabits the small bowel
- Infection more severe in immunocompromized people(e.g. HIV/AIDS, malnutrition, intercurrent disease)
Give examples of tissue nematodes
- toxocara
- trichinella
Give examples of Filarial nematodes
- Onchocerra
- Wuchereria and Brugia
Describe toxicara as a pathogen
- a tissue nematode
- a world wide infection of dogs and cats
- Human infection occurs when embryonated eggs are ingested from dog or cat faeces
Describe Trichinella as a pathogen
- a tissue nematode
- Associated with consumption of infected and unfrozen or poorly cooked meat
- Encysted larvae occur in striate muscle and symptoms occur based on location
Describe Onchocerra as a pathogen
A filarial nematode
- Transmitted by black fly
- Causes visual impairments, blindness severe itching of the skin in infected individuals
Describe Wuchereria and Brugia as a pathogen
Wuchereria and Brugia
- filarial nematodes
- the major causative agent of lymphatic filariasis
What are the General features of Trematodes(flukes)?
- Trematodes have a dead-end digestive system, nutrients are taken and expelled from the same opening
- Trematodes and cestodes are both classified into the phylum, Platyhelminth/flatworms
Describe the life cycle of Trematodes
Trematode life cycle involves more than one host, a mollusk and a vertebrate
Give examples of Trematodes(flukes)
- Fasciolopsis (intestinal fluke)
- Fasciola (liver fluke)
- Paragonimus(lung fluke) and Clonorchus(Chinese liver fluke)
Describe Fasciolopsis as a pathogen
- Fasciolopsis (intestinal fluke)
- A common parasite of human and pigs
- One of the largest Trematodes to infect man lives in the upper intestine
- Chronic infection leads to inflammation, ulceration and hemmorhage of the small intestine
Describe fasciola as a pathogen
- A parasite of sheep, humans become infected when ingest metacercariae that have encysted on watercress
- The adult trematode lives in the intra-hepatic bile ducts of the liver. “Fascioliasis” can lead to severe anaemia in humans
Describe Paragonimus (lung fluke) and Clonorchis(Chinese liver fluke)
- a wide spread in the Far East and South East Asia
- The parasite is acquired by ingestion of infective metacercariae in raw or pickled crustaceans
Give details of the anatomy of Cestodes/tapeworms
Tapeworms have flat segments called proglottids develop sequentially from a head called the scolex
The worm has no digestive tract but absorbs nutrients directly into the proglottis and scoleces
Give the function of the scolex
The scolex of the cestodes(tapeworms) contains suckers and/or hooks used to attach to the intestinal epithelium
What are the usual hosts of Cestodes(tapeworms)?
Humans are usually the definitive hosts. When they are the immediate hosts more serious disease occurs
Describe the sexual reproduction of cestodes(tapeworms)
Tapeworms are hermaphroditic, each proglottid producing sperm and egg, and engaging in self-fertillization , releasing fertilized eggs.
Proglottids May break off sequentially from the elongating tapeworm bodies as well
Give examples of intestinal tapeworms
Taenia(beef tapeworm)
Taenia(pork tapeworm)
Describe the pathogenicity of Taenia(beef tapeworm)
Occurrence worldwide
- acquired via ingestion of contaminated, uncooked beef
- a common infection but causes minimal symptoms
Describe the pathogenicity of Taenia(pork tapeworm)
- occurrence worldwide
- Acquired by ingestion of contaminated, uncooked pork that contains cystercerci
- less common, but causes cysticercosis-a systemic disease where cysticerci encyst in muscles and in the brain and may lead to epilepsy
Give an example of systemic tapeworms
Eichinococcus(dog and rodent tapeworms)
Describe the pathogenicity of Systemic tapeworms
- hyadatid disease occurs when the larval stages of these organisms are ingested
- The larvae May develop in the human host and cause space-occupying lesions in several organs e.g. brain, liver
Patient has space-occupying lesions on liver,brain and other organs, what is at play?
Echinococcys-systemic tapeworm
A woman obtains a pathogen from a black fly and becomes visually impaired and has severe itching, what is the pathogen?
Onchocerra-filarial nematode
A patient is immunocompromised, what pathogens are they at risk of receiving?
Strongyloides- intestinal nematodes of the small bowel
Cryptosporidium parvum- intestinal protozoan
A patient has been exposed to both the TseTse fly and reduviid bug, what diseases and pathogen are they at risk of?
Tryponasoma
Africa-sleeping suckness(tsetse fly)
South America -Chaga disease(reduviid bug)
What is a fungus?
A heterotrophic eukaryotic organism whose cell wall is made of chitin
