Chapter 4 Flashcards
Paleontology
The study of the history of life on earth as seen through fossils
It is believed that bacteria, archaea, and eukaryotes evolved directly from the _______________, which was neither prokaryotic nor eukaryotic.
last common ancestor
Complex multicellular organisms evolved as individual cells in the organism lost the ability to survive apart from the ___________.
Colony
Eukaryotes that are traditionally studies by microbiologists
Primarily protozoa, microscopic algae, fungi, and helminths.
Which eukaryotic organism is always unicellular?
when considering organisms traditionally studies by microbiologists
Protozoa
Which eukaryotic organism may be unicellular or multicellular?
(when considering organisms traditionally studies by microbiologists)
Fungi and algae
Which eukaryotic organism is always multicellular?
when considering organisms traditionally studies by microbiologists
Helminths (but have unicellular egg or larval forms)
Outcome 1 in 4.1: Relate the bacterial, archaeal, and eukaryotic cells to the Last Common Ancestor.
These microorganisms evolved directly from the LCA, which was neither eukaryotic nor prokaryotic.
Outcome 2 4.1: List the types of eukaryotic microorganisms, and identify which are unicellular and which are multicellular.
-Protozoa, Algae, Fungi, Helminths
Protozoa= always unicellular Algae/Fungi= may be uni or multi Helminths= always multicellular (eggs/larva are uni)
The first primitive eukaryotic cells were likely single-celled and independent, but over time ________ and formed ________, evolving to have specific _____.
- Aggregated
- Colonies
- Functions
Outcome 1 4.2:
Differentiate among the flagellar structures of bacteria,
eukaryotes, and archaea.
Eukaryotes: 10x thicker than bacterial flagella, structurally more complex, covered by an extension of the cell membrane, 9+2 arrangement; cilia may be present and function in feeding, motility, and filtering structures, very small compared to flagella but are shorter and more numerous
Outcome 2 4.2:
List similarities and differences between eukaryotic and
bacterial cytoplasmic membranes.
Outcome 3 4.2:
Briefly list the components and characteristics of each
organism type.
Outcome 4 4.2:
Explain how endosymbiosis contributed to the
development of eukaryotic cells.
Glycocalyx of Eukaryotic cells
- outermost layer that comes into direct contact with environment
- called extracellular matrix
- composed of polysaccharides
- appears as network of fibers, a slime layer, or a capsule
- protection, adherence to surfaces, reception of signals from other cells and the environment
Cell Wall of Eukaryotes
-protozoa/helminths do not have
Fungi do:
- cell walls are rigid
- provide structural support
- different from composition of bacterial/archaeal cells
- have an inner layer of polysaccharide fibers composed of chitin or cellulose
- outer layer of mixed glycans
Order of Cell Wall Outer to Inner:
mixed glycans->glycoprotein->chitin or cellulose and the cell membrane which is not part of the cell wall
Cell Membrane of Eukarya
- phospholipid bilayer (proteins embedded)
- sterols (rigid form of lipid, allows more stability in membrane compared to non-eukaryote cells)
- selectively permeable
Internal structures of eukarya
- membrane bound organelles
- organelles account for 60-80% of cell volume
- organelles contained in fluid called cytosol/cytoplasm (except nucleus)
Nucleus
- separated from cell cytoplasm by nuclear envelope
- nucleoplasm
- pores/passageways
- nucleolus (site of ribosomal RNA synthesis)
- chromatin can be found in nucleolus (linear DNA, later forms chromos)
Endoplasmic Reticulum
- series of membrane tunnels
- transportation and storage
- smooth and rough
- RER is continuation of nuclear envelope and transports/packages materials from nucleus to cytoplasm *ribos attaches
- SER functions in nutrient processing and synthesis/storage of nonprotein macromolecules such as lipids
Golgi Apparatus
- protein modification and transport to final destination
- stacked cisternae (composition)
- forms vesicles to be secreted outside of cell
Lysosome
- buds of golgi
- digestion of food, removal of cell debris
Vacuole
- contain fluids or solid particles to be digested, excreted, or stores
- Protozoa living in freshwater habitats use structures called contractile vacuoles to regulate osmotic pressure
Mitochondria
- aerobic (with oxygen) respiration
- extracts chemical energy from nutrient molecules and stores it a ATP
- mitochondria (and chloroplasts) divide independently of cell
- contain DNA and ribos
- suggested that they may have once been bacteria cells that evolved
-protozoa have mitosomes
Chloroplasts
- found in algae and plant cells
- convert sunlight into chemical energy for photosynthesis
- oxygen gas biproduct
Ribosomes
- 80S variety
- protein synthesis
Cytoskeleton
- flexible framework
- anchors organelles
- moves RNA and vesicles
- permits shape changes
- movement in come cells
- actin filaments (contraction, crawling, pinching)
- intermediate filaments (10nm, structural reinforcement of cell)
- microtubules (long hollow tubules= transport substances from one part of the cell to another, mitosis, movement of cilia and flagella)
Characteristics of each organism type:
Genetics
Eukaryotes have nucleic acids, chromos, nucleus and nuclear envelope
Bacteria/Archaeal: only have nucleic acids and chromos
Viruses: only have nucleic acids
Characteristics of each organism type:
Reproduction
Eukaryotes: have mitosis, sex cell production, and binary fission
Bacteria and Archaeal: only have some sex cell production and binary fission, NO MITOSIS
Viruses: none
Characteristics of each organism type:
Biosynthesis
Eukaryotes: independent, golgi, endoplasmic reticulum, and ribosomes
Bacterial/Archaeal: only independent and ribosomes
Viruses: none
Characteristics of each organism type:
Respiration
Eukaryotes: mitochondria
Bacteria/Archaea: no mitochondria
Viruses: no mitochondria
Characteristics of each organism type:
Photosynthesis
Eukaryotes: some have pigments and chloroplasts
Bacteria/Archaea: some have pigments, NO chloroplasts
Viruses: NEITHER
Characteristics of each organism type:
Motility/Locomotion Structures
Eukaryotes: Some have cilia and flagella
Bacteria/Archaea: some have flagella, NO CILIA
Viruses: NONE
Characteristics of each organism type:
Shape/Protection
Eukaryotes: YES-> membrane SOME-> cell wall SOME-> glycocalyx
Bacteria/Archaea: YES-> membrane YES-> cell wall SOME-> glycocalyx
Viruses: SOME HAVE MEMBRANES “ENVELOPES”
Characteristics of each organism type:
Complexity of Fx
Eukaryotes: COMPLEX
Bacteria/Archaea: COMPLEX
Viruses: SOME-> complex
Characteristics of each organism type:
Size in general
Eukaryotes: 2-300 micrometers
Bacteria/Archaea: 0.5-3 micrometers (although much smaller/larger bacteria exist)
Viruses: 0.2 micrometers
Endosymbiosis
theory that eukaryotic cells came to be when primordial cell types engulfed bacteria or other primordial cell types that later became organelles inside the more complex cells
4.3 List two detrimental and two beneficial activities of fungi
(from the viewpoint of humans).
4.3 The Fungi:
Differentiate among the terms heterotroph, saprobe, and
parasite.
In medical micro we are most concerned with the fungi known as ______ and _____.
yeasts and molds
Fungi:
Yeast cell
-round to oval shape
-cell wall
-asexual reproduction
grows “buds” on surface which then become separate cells
Although the majority of fungi are either unicellular or colonial, a few complex forms such as mushrooms and puffballs are truly ________.
multicellular
cells of the microscopic Fungi exist in two basic forms:
yeasts and hyphae
Form of Fungi:
Hyphae
- long, threadlike cells found in bodies of fungi of the filamentous type
- these are called molds
Pseudohypha
A chain of easily separated, spherical to sausage-shaped yeast cells partitioned by constrictions rather than by septa
- formed when buds remain attached in a row
- because of formation not a true hypha like that of molds
Dimorphic
fungal cells that can take either a mold or yeast form depending on growth conditions such as temperature
*several fungi that cause human disease are dimorphic
Nearly ____ species of fungi can cause human disease
300
CDC Types of Fungal Disease in Humans
- Community acquired infections caused by environmental pathogens
- Hospital associated infections caused by fungal pathogens in clinical setting
- Opportunistic infections caused by low-virulence species infecting already-weakened individuals
Community Acquired Infections
Who is affected: general population
Example: ringworm, a fungal infection
Sites of Sx: skin in various regions inc. scalp, groin, feet
Example: Coccidioidomycosis (valley fever) caused by fungus that lives in soil and dust
Site of Sx: flulike in resp. tract and rest of body
Hospital-Associated Infections
Who is affected: patients in LTC and hospital
Examples: various fungi that contaminate healthcare facilities
Sites of Sx: could be anywhere
Opportunistic Infections
Who is affected: people with compromised immune systems, or disrupted microbiota
Example: Mucormycosis caused by a fungus found in soil, leaves, compost, and rotting wood
Sites of Sx: lungs and sinuses, skin also
Example: candidiasis caused by a yeast infection
Site of Sx: tongue, vagina, skin, wherever the microbe normally lives in small numbers
Mycoses
term for fungal infections
Transplant patients, cancer patients, and HIV pos patients are much more susceptible to _________ infections.
Opportunistic
Aspergillus flavus
a mold that synthesizes a potentially lethal poison called aflatoxin; consumption can lead to liver cancer
Fungi and Agriculture
; estimated that 40% of yearly fruit crop is consumed by fungi
; can be damaging to field plants like corn and grain and to domestic animals that may ingest these crops
; essential role in decomposing organic matter and returning essential minerals to the soil
; increase roots’ ability to absorb water
The yeast Saccharomyces
produces the alcohol in beer and wine and the gas that causes bread to rise
Heterotrophic and fungi
an organism that relies upon organic compounds for its carbon and energy needs
Saprobes and fungi
they obtain substrates from the remnants of dead plants and animals in the soil or aquatic habitats
Substrates
the specific molecule upon which an enzyme acts
Parasite and fungi
fungi can also be parasites on the bodies of living animals or plants;
; obtains nutrients and protection from host and causes some degree of harm to the host
Often found in nutritionally poor or adverse environments
Fungi
Various _____ thrive in substrates with high salt or sugar content, at high temperatures, and even in snow and glaciers
; fungi
Mycelium
the filamentous mass that makes up a mold; composed of hyphae
_______’s cells grow in loose associations or colonies
Fungi’s
Septum/Septa
a partition or cellular cross wall, as in certain fungal hyphae
; some septa may be solid and allow no communication
; other septa may have small pores that allow for flow of organelles and nutrients between adjacent septum compartments
Vegetative hyphae (fungi)
responsible for the visible mass of growth that appears on the surface of a substrate and penetrates in to digest and absorb nutrients
; can give rise to reproductive hyphae
- vegetative mycelium are responsible for fungal production of spores
Fungi Benefits
-can help produce organic acids, alcohol, vitamins, and antibiotics
How many species of protozoa are there?
about 12,000
Protozoan are ______ cells containing all major eukaryotic organelles
single
Protozoan organelles are specialized for what functions?
feeding
reproduction
locomotion
Endoplasm-inner layer housing the nucleus, mitochondria, and food and contractile vacuoles
Ectoplasm-outer layer, clear, involved in locomotion, feeding, and protection
Protozoan cytoplasm composition
Pseudopods, flagella, and cilia in protozoans
“false feet”
help protozoan move through fluids
True or False:
Protozoan have a cell wall.
False
; because of this they have more flexibilty
Protozoan cell membrane
regulates movement of food, wastes, and secretions
; cell shape can remain constant (as in most ciliates) or change constantly (as in ameobas)
Size of most protozoan cells
3-300 micrometers
*giant amoebas and ciliates can be 3-4mm in length.
Main limiting factor of protozoa
availability of moisture
; their primary habitats are fresh and marine water, soil, plants, and animals
*even extremes in temp and pH are not barriers to them
; hardy species are found in hot springs, ice, habitats with very low or high pH
Special feeding structures of protozoa
Oral Grooves: carry food particles into a passageway or gullet that packages the captured food into vacuoles for digestion
Some protozoa absorb food directly through their cell membrane
Pathogenic species may live on the fluids of their host, such as plasma and digestive juices, or can actively feed on tissues
Greek for “first animals”
Protozoa
Mainly harmless, but the few pathogenic species of this eukaryotic organism are responsible for millions of infections each year
Protozoa
Protozoa are __________ and require food in complex organic forms
heterotrophic
Free living species of ________ scavenge dead animal or plant debris or graze on bacteria and algae
protozoa
Trophozite
a vegetative protozoan (feeding form) as opposed to a resting (cyst) form.
Four groups of protozoa based on their motility
- Sarcodina (pseudopods)
- Ciliophora (cilia)
- Mastigophora (flagella)
- Sporozoa (gliding motility)
Example of a disease caused by Amoeboid Protozoa
Entamoeba histolytica -> Amoebiasis (intestinal + other symptoms)
Reservoir: humans, water, food
Naegleria, Acanthamoeba -> brain infection
Example of a disease caused by Ciliated Protozoa
Balantidium coli -> Balantidiosis (intestinal + other symptoms)
Reservoir: pigs, cattle, primates
Example of a disease caused by Flagellated Protozoa
Trichomonas vaginalis -> Trichomoniasis (vaginal sx)
Reservoir: human
Giardia lamblia -> Giardiasis (intestinal distress)
Trypanosoma brucei, T, cruzi -> Trypanosomiasis (intestinal distress and widespread organ damage)
Leishmania donovani -> Leishmaniasis (either skin lesions or widespread involvement of internal organs)
Example of a disease caused by Apicomplexan Protozoa-Nonmotile
Cyclospora cayetanensis -> Cyclosporiasis (intestinal and other sx)
Reservoir: water, fresh produce
Plasmodium vivax -> Malaria (cardiovascular + other symptoms)
Toxoplasma gondii -> Toxoplasmosis (flu like/silent infection)
Cryptosporidium ->Cryptosporidiosis (intestinal + other symptoms)
Outcomes for 4.4:
Describe the protozoan characteristics that illustrate why
protozoa are informally placed into a single group.
Give an example of a disease caused by each of the four
types of protozoa
- they have an inner and outer layer of cytoplasm (endoplasm and ectoplasm)
- no cell wall
- can move through fluids with attachments
- have cell membranes that regulate waste, secretions, and food
- Amoeboid Protozoa -> Amoebiasis (intestinal)
- Ciliated Protozoa -> Balantidiosis (intestinal)
- Flagellated Protozoa: Trichomoniasis (vag sx)
- Apicomplexan Protozoa-Nonmotile -> cyclosporiasis (intestinal)
Tapeworms, flukes, and roundworms are _______
Helminths
Two major groups of pathogenic helminths
Flatworms (phylum Platyhelminthes)
Roundworms (phylum Aschelminthes, also called NEMATODES)
Characteristics of Flatworms (phylum Platyhelminthes)
very thin, often SEGMENTED body plan
Characteristics of Roundworms (phylum Aschelminthes)
elongated, cylindrical, UNSEGMENTED body
Flatworm Subdivisions
Cestodes, or tapeworms (named for their long, ribbon-like arrangement)
AND
Trematodes, or flukes (characterized by flat, ovoid bodies)
True or False:
All flatworms and roundworms are parasites by nature
False; many live free in soil and water
All helminths are ________ animals equipped to some degree with organs and organ systems.
Multicellular
In pathogenic helminths, the most developed organs are those of the __________ system.
Reproductive
Ascaris lumbricoides
Roundworm; Nematodes
Disease: Ascariasis
Enterobius vermicularis
Roundworm; Nematodes
Disease: Pinworm
Trichinella spiralis
Roundworm; Nematode
Disease: Trichina worm
Onchocerca volvulus -> River blindness
Dracunculus medinensis -> Guinea worm
Roundworms; Nematodes
Schistosome japonicum - > blood fluke
Flatworm; Trematodes
Taenia solium -> pork tapeworm
Diphyllobothrium latum -> fish tapeworm
Flatworms; Cestodes
Pinworm size
worms range from 2-12mm long
Egg Laying of Helminths
- Eggs picked up from environment from another infected person directly or by touching articles that person has touched
- Eggs hatch in intestine and female and male worms mate
- Female worm deposits eggs at anus and causes itchiness making host scratch and spread eggs on surfaces
- Fertilized eggs are vulnerable to heat, cold, dryness, and predators
- Helminths can lay 25,000-25 million eggs a day to ensure completion of life cycle
*Hard outer shell of eggs for protection
About ___ species of helminths cause disease in humans.
Pathogenic helminths are frequently called _____.
50
Parasites
Distribution and Importance of Parasitic Worms
- distributed in all areas of world
- about 50 species that cause disease in humans
- high incidence in tropical areas
- yearly cases are in the billions and not confined to developing countries
- conservative estimate of 50 million helminth infections a year in North America alone
