Exam 3 Flashcards
How is the phylogenetic tree determined? (3.9)
- Relatedness based on comparing sequences of Small Subunit Ribosomal RNA (SSU rRNA)
- –Bacteria and Archaea: 16S rRNA
- –Eukarya: 18S rRNA
Phylum [definition] (3.9)
Group sharing a common ancestor
Genus [definition] (3.9)
Well defined group of one or more strains
By what system are microbes named? (3.9)
- A binomal system
- Genus and species
Thermus aquaticus [bacteria] (21.2)
- Grows at 70 - 75 C
- Source of Taq polymerase for PCR
- In phyla Thermus
Deinococcus radiodurans [bacteria] (21.2)
- Not thermophilic
- Extremely resistant to radiation and dessication
- In phyla Deinococcus
Cyanobacterium [phyla overview] (21.4)
- Primary producers in many ecosystems
- Undergo oxygenic photosynthesis
- –Water oxidized (electron donor), produces oxygen
- –Two photosystems
- –Calvin cycle to fix CO2 into carbohydrate
- Contain subcellular structures
- –Chlorophyll
- –Thylakoids
- –Carboxysomes
- —–Found in cytoplasm
- —–Where calvin cycle takes place with the use of the protein RubisCO
Anabena [bacteria] (21.4)
- Type of cyanobacteria
- Gram negative
- Aquatic
- Both oxygenic photosynthesis and nitrogen fixation take place
- –Problem with this: Enzyme nitrogenase for Nitrogen fixation is sensitive to the O2 produced by oxygenic photosynthesis
- –Solution: Differentiate vegeatative cells into hetercyst cells devoid of O2 that fix N2
- Fig. 21.12
Chlamydia [phyla] (21.6)
- Part of phylum Chlamydiae
- Gram negative
- Obligate intracellular bacteria
- –Require a host cell to reproduce, similar to a virus (but it is NOT a virus)
- Human and animal pathogens
Chlamydia trachomatis [bacteria] (21.6)
- Part of phylum Chlamydiae
- Causes #1 reported STI in the US
- Unique developmental cycle - Contains two distinct cell types (dimorphic)
Chlamydia Cell Types [two types] (21.6)
i) Elementary Body (EB)
- –Dormant, infectious
- –Attaces, enters, & develops into a reticulate body
ii) Reticulate Body (RB)
- –Reproductive, non-infectious, intracellular
- –Develops back into EB – leads to cell lysis
Spirochaetes [phyla overview] (21.7)
- Flexible, helical shape
- Flagella contained within the periplasm – underneath the outer membrane
- –Axial filament
- –Flagella rotation turns the whole cell
- Pathogens
Treponema pallidum [bacteria] (21.7)
- Cause of syphillus
- In phyla Spirochaetes
Borrelia burgdorferi [bacteria] (21.7)
- Cause of Lyme Disease
- Tick bite, causes bulls-eye rash
- In phyla Spirochaetes
Bacteroidetes [phyla overview] (21.8)
-Obligate anaerobes
Bacteroide [bacterial genus] (21.8)
- In phyla Bacteroidetes
- Anaerobic
- Gram negative
- Major component of intestinal microflora
- Degrade complex dietary polysaccharides
Proteobacteria [phyla overview] (22)
- Largest group
- Contains five major classes: Alpha, Beta, Gamma, Delta, and Epison
- Diverse cell forms & metabolism
- –Heterotrophs, phototrophs, and lithotrophs all contained in this phyla
Alpha Proteobacteria [class overview] (22.1)
- Some are photoheterotrophs
- –All that undergo photosynthesis do so anoxygenically (do not produce oxygen)
- Some are endosymbionts
Rhodospirillum [bacterial genus] (22.1)
- Part of class Alpha Proteobacteria
- A photoheterotroph
- Undergoes anoxygenic photosynthesis
Rhizobium [bacterial genus] (22.1)
- Part of class Alpha Proteobacteria
- An endosymbiont
- Produces root nodules on plants
- Symbiotic relationship with plants – It fixes N2 into ammonia for the plants to use, and in return, the plant gives it a place to live & food
- Essentially a fertilizer
Agrobacterium [bacterial genus] (22.1)
- Part of class Alpha Proteobacteria
- Causes plant tumors (galls)
- Not a symbiotic relationship with plants– it kills them
Rickettsia [bacteria genus] (22.1)
- Part of class Alpha Proteobacteria
- Occurs in animals
- Obligate intracellular bacteria (requires host to reproduce)
- Cause of Rocky Mountain Spotted Fever
- –From tick bites
Caulobacter [bacterial genus overview] (22.1)
- Gram negative
- Aquatic
- Dimorphic
- –Gives rise to two distinct cell types
Caulobacter Cell Types [two types; bacterial genus] (22.1)
i) Swarmer cell
ii) Stalked cell
Caulobacter Swarmer Cell (22.1)
- Motile ; Contains a flagella
- Cannot replicate its DNA – must transform into stalked cell to do so
- To transform into stalked cell, it ejects its flagellum, and a stalk will grow in its place
- Fig. 22.10
Caulobacter Stalked Cell (22.1)
- Non-motile
- Contains a stalk
- –Increases surface area of cell, attachment
- Has a Holdfast at the tip of the stalk
- Can replicate
- –Creates new swarmer cells, NOT new stalked cells
Caulobacter Stalk Holdfast (22.1)
- Made of polysaccharides
- Very sticky
- –Bonds more strongly than superglue
Beta Proteobacteria [class overview] (22.2)
- Some are lithotrophs
- –Oxidize nitrate, sulfur, and iron
- Some are important human pathogens
Nitrosomonas [bacterial genus] (22.2)
- Part of class Beta Proteobacteria
- A lithotroph
- Oxidizes ammonia to nitrite
- First step of nitrification
- –Important part of processing wastewater
Neisseria meningitidis and Neisseria gonorrhoeae [bacteria] (22.2)
- Part of class Beta Proteobacteria
- Cause of meningitis and gonorrhea
- Gram negative
- Diplococcus
Gamma Proteobacteria [class overview] (22.3)
- Includes a lot of enterics
- –Bacteria in human & animal intestinal tract
- Facultative anaerobes
- –Prefer oxygen but can live without it
- Includes some non-enterics as well
Escherichia coli [bacteria] (22.3)
- Part of class Gamma Proteobacteria
- Some strains are normal inhabitants of the intestinal tract (enteric)
- Some strains are pathogenic
- –O157:H7
Salmonella [bacterial genus] (22.3)
- Part of class Gamma Proteobacteria
- Enteric
- Cause of food poisoning
Proteus [bacterial genus] (22.3)
- Part of class Gamma Proteobacteria
- Cause of urinary tract infections (enteric)
- Has a ton of flagella covering its entire surface (peritrichous)
- –This helps it stay in the urinary tract even with the flow of urine
Psuedomonas aeruginosa [bacteria] (22.3)
- Part of class Gamma Proteobacteria
- Opportunistic pathogen
- –Will generally not hurt healthy people
- –Infects people with cystic fibrosis, burn patients, etc with compromised immune systems
Shewanella [bacterial genus] (22.3)
- Part of class Gamma Proteobacteria
- Non-pathogenic
- Found both aquatically and in soil
- Conducts extracellular electron transport
Myxococcus [bacterial genus] (22.4)
- Part of class Delta Proteobacteria
- Gram negative
- Social
- Found in soil
- Attack other bacteria in “packs”
- Gliding motility (no flagella)
- Under nutrient limiting conditions, cells assemble into fruiting bodies
- –Contain dormant myxospores
Epsilon Proteobacteria [class overview] (22.5)
- Smallest class in this phyla
- Two major genera that cause human disease
- –i) Campylobacter
- —–Causes Septicemia & Gastroenteritis
- –ii) Heliobacter
- —–Causes Gastritis and Peptic Ulcer Disease
Firmicutes [bacterial phyla] (23)
- Low G+C
- –Low in guanine and cytosine in DNA
- Gram Positive
- Contains pathogens
- –Staphylococcus (MRSA)
- –Streptococcus
Bdellovibrio [bacterial genus] (22.4)
- Part of class Delta Proteobacteria
- Uses its flagella to slam into other bacteria
- Parasitizes other bacteria
- Enters & grows inside of the periplasm
- Lyses the host cell
Clostridium [bacterial genus] (23.1)
- In phyla Firmicutes
- Forms spores
- Low G+C, Gram Positive
- C. botulinum
- –Makes a neurotoxin (Botox)
- C. difficile
- –Causes colitis
- –Inflammation of colon
Bacillus [bacterial genus] (23.2)
- In phyla Firmicutes
- Forms spores
- Low G+C, Gram Positive
- B. subtilis
- –Non-pathogenic
- B. anthracis
- –Pathogenic
- B. thuringiensis
- –Makes insecticidal toxin (Bt corn)
Bacillus Sporulation (23.2)
- Adaptive response to starvation
- Takes 8 - 10 hrs to kill a spore
- Two cell involved in sporulation
- –i) Mother cell - Lyses & releases mature spore
- –ii) Forespore - Mature spore
- Spore: Dormant, stress-resistant, but can germinate (become an actively growing cell) when the environment becomes favorable
Three Key Events in Bacillus Spore Formation (23.2)
i) Septum forms asymmetrically (not in the center)
ii) Mother cell engulfs the spore and gives the spore an outer membrane
iii) Mother cell then adds a cortex of peptidoglycan and protein, then lyses to release the mature spore
Spore Cell Morphology (23.2)
- Chromosome in the innermost part of the spore
- Inner membrane covers the chromosome
- Cortex of peptidoglycan and protein (from mother cell) covers the inner membrane
- Outer membrane (from mother cell) covers cortex layer
- A coat of protein makes up the outermost layer of the cell
How does a Cell Know When to Undergo Sporulation? (23.2)
- Sporulation requires gene expression at precise times and places
- Signal Transduction Cascade
- Sigma Factor Cascade
Signal Transduction Casade (23.2)
- A two component system
i) Sensor kinases sense starvation (changes in environment)
ii) Response regulators activate transcription of early spore genes
Sigma Factor Cascade (23.2)
- Guides RNA polymerase to certain promoters
- The sigma factors tell the cell to begin translation of sporulation genes
Actinobacteria (24)
- High G+C, Gram Positive Bacteria
- Genus: Mycobacterium
- Genus: Streptomyces
Mycobacterium [bacterial genus] (24.1)
- Part of phyla Actinobacteria
- High G+C, Gram Positive
- Two important species: tuberculosis & leprae
- Acid-fast cell walls
- Waxy lipids
Streptomyces [bacterial genus] (24.1)
- Part of phyla Actinobacteria
- High G+C, Gram Positive
- Form hyphae & mycelia
- Source of many antibiotics
What are the two groups of eukaryotic microorganisms? (25, 26)
- Protists
- Fungi
Five Main Characteristics of Eukaryotic Organisms (5.1)
i) Sexual & Asexual Reproduction
ii) Have a membrane-bound nucleus
iii Contain plasma membranes (lipid bilayers)
iv) Many have cell walls
v) Have membrane-enclosed organelles
How does a eukaryotic organism undergo asexual reproduction?
i) Binary Fission
ii) Budding
How does a eukaryotic organism undergo sexual reproduction?
- Sexual cells called gametes fuse together to form a diploid zygote
- Undergo meiosis
Endoplasmic Reticulum (5.4)
- An organelle
- Carry the ribosomes
- Where protein synthesis occurs
Golgi Apparatus (5.4)
- An organelle
- Where proteins undergo chemical modification, packaging, and preparation for secretion from the cell
Mitochondria (5.6)
- An organelle
- Powerhouse of the cell
- ATP by electron transport & oxidative phosphorylation
- Site of the TCA cycle
General Features of Protists (25.1)
- Usually unicellular
- Contain algae, slime molds, and protozoa
- –Algae and slime molds: Photosynthetic
- –Protozoa: Chemoorganotrophic
- Found both terrestially and aquatically
- Motile via cilia, flagella, or psudopodia
- Undergo sexual and/or asexual reproduction
- Some are parasitic, but not all
How are protists an important link in food chains? (25.1)
- Plankton in aquatic habitats
- Radiolarians, Diatoms, Formaniferans
- –Silica, calcium carbonate walls
- –Reef formation, beach sand, limestone
Ciliates (25.1)
- Protists with two types of nuclei
i) Micronucleus
ii) Macronucleus
Micronucleus (25.1)
- Small nucleus in ciliates, part of the macronucleus
- “True” nucleus– this is the one that undergoes mitosis
- Contains genes for sexual reproduction
Macronucleus (25.1)
- Large nucleus in ciliates
- Thousands of short, linear chromosomes
- Genes devoted to growth & feeding
- Does not help in the replication of the cell
Vacuoles (5.3)
- Two types
i) Contractile - –Osmoregulatory
- –Expel water
ii) Phagocytic - –Food digestion
Encystment (25.1)
- Development into dormant stage of a protist
- Protection, transmission
Excystment (25.1)
- Escape from cyst to metabolically active, motile form of a protist
- Trophozoite
Metabolism and Nutrition in Protists (25.1)
- Metabolism
- –Can be photosynthetic (oxygenic)
- –Can be chemoorganoheterotrophs & mixotrophs (mix of organic & inorganic)
- Nutrition
- –Solid nutrients by phagocytosis
- –Soluble nutrients by facilitated diffusion and active transport
Chlamydomonas [protist genera] (25)
- Single-celled green alga
- Contains a cell wall made of cellulose
- Performs oxygenic photosynthesis
- Motile
- –Two flagella
- Stigma (eyespot) plays role in phototaxis
- –Moves based on light in surroundings
- Both sexual & asexual
Dictyostelium [protist genera] (25.3)
- A cellular slime mold
- Free-living amoeboid cells aggregate together to form a motile ‘slug’– comprised of 20,000+ individual cells
- –Use cAMP for signaling
- The slug eventually stops moving and forms a fruiting body with spores
- Spores germinate, give rise to free-living amoeboid cells again
Giardia [protist genera] (25.2)
- Parasite
- Human pathogen
- –Cysts ingested
- –Trophozoites attach to intestine via ‘sucking discs’
- –Disrupts nutrient uptake; H2O flood causing severe diarrhea
- –Animal reservoirs, human carriers
Alveolata [protist group] (25.5)
-Includes the dinoflagellates, ciliates, & apicomplexans
Dinoflagellates [protist group] (25.5)
- Cause of “red tide”– fluorescence in ocean
- –Generally found in marine plankton
- Phototrophy, heterotrophy, & mixotrophy all observed
Ciliates [protist group] (25.5)
- Includes about 12,000 different species
- –All are chemoorganotrophic
- Most have two types of nuclei– macronucleus and micronucleus
Apicomplexans [protist group] (25.5)
- Important causes of human disease
- –Cryptospoidosis (caused by Cryptosporidium_
- –Toxoplasmosis (caused by toxoplasmosa)
- –Malaria (caused by Plasmodium falciparum)
Cryptosporidosis (25.5)
- Human disease cause by protist Cryptosporidium
- Transmitted in contamintaed water (feces from infected person or animal)
- Milwaukee 1993: 400,000 cases
- Oocysts ingested
- –Oocysts: Small, chlorine-resistant, & stable
- Excystment to become trophozoites in intestine
Toxoplasmosis (25.5)
- Oocysts from raw or undercooked meat or cat feces
- Mice are a natural reservoir
- Cats are hosts – required to complete sexual cycle
- Ingested oocysts become tachyzoites – localize in neural & muscle tissue
- –Can enter brain
- –Can cross placenta
Malaria (40.3)
- Caused by four species of Plasmodium
- –The one we care about it Plasmodium falciparum
- Transmitted by the bite of infected female Ancopheles mosquito
Plasmodium falciparum Sexual Cycle inside Human Host (40.3)
- –The cycle that occurs within the human host is the ASEXUAL cycle. This protists’ sexual cycle occurs in the mosquito, but we don’t need to know about it
i) Sporozoites injected into human host with the saliva of the mosquito - –Within minutes, these sporozoites hone in on liver cells
ii) Sporozoites penetrate liver cell
iii) In liver, sporozoites become merozoites
iv) Merozoites release from liver, covered in liver cell membrane (‘trojan horse’)
v) Merozoites attach & affect red blood cells & reproduce, then lyse host cell & affect more red blood cells – cyclic - –The parasite forms knobs on the red blood cell surface which cause them to attach to the blood vessel wall so that they will not be processed by the body before the merozoites can reproduce
- In the Sexual Cycle (not in human host), Gametocytes taken up by mosquito & give rise to sporozoite form
Clinical Signs of Malaria (40.3)
- Periodic chills and fever
- –Have subsiding periods when the merozoites are moving to new host cells
- Anemia
- Liver and spleen - Hypertrophy
Malaria - Control, Prevention, Treatment (40.3)
- Mosquito Control - Wetland drainage, insecticides, Bed netting
- Drugs
- –i) Chloroquine
- —–Parasite degrades hemoglobin as nutrient source. When it does this, it releases a toxic heme. The parasite then polymerizes this toxic heme into a non-toxic form. This drug blocks that polymerization, causing the toxic heme to kill the parasite
- –ii) Malarone
- —–Blocks electron transport and pyrimidine synthesis
- —–Not super important, but apparently this drug has a common side effect of causing very vivid and colorful dreams
Histoplasma capsulatum [fungi] (26)
-A fungi that can take the form of a mold (with sexual reproduction) or a yeast (with asexual budding reproduction)
General Features of Fungi (26)
- Eukaryotic
- Size: Single-celled yeast to 3-mile-wide Honey Mushroom
- Lack chlorophyll
- Contain plasma membranes
- Cells walls composed of chitin (polymer of NAG)
- Saprophytes
- –Nutrients from dead organic matter
- Absorptive
- –Secrete enzymes, then absorb nutrients (pre-digestion)
- Very important decomposers
Mycology (26)
Study of fungi
Mycoses (26)
Diseases caused by fungi
Mycotoxicosis (26)
- Poisoning by fungal toxin
- Aflatoxins - Intercalate into DNA; Carcinogens
- –Aspergillus [fungi containing aflatoxins]
- Ergot alkaloids - Cause delusions, convulsions
- –Calviceps [fungi containing ergot alkaloids, found on wheat]
Distribution of Fungi (26.1)
- Mostly terrestrial
- Can be part of human microflora
- Can be pathogens
- Can form associations
- –Lychens: Fungi and Cyanobacteria
- –Myccorhizal Fungi: Fungi on Plant Roots
- —–Mutualism of fungi with other species & kingdoms of life
Yeasts (26.1)
Unicellular fungi
Saccharomyces cerevisiea [fungi] (26.1)
- Type of yeast
- Ferment & used in beer, wine, bread
Candida albicans [fungi] (26.1)
- Type of yeast
- Microflora of mouth, vagina, & intestinal tract
- Cause of Thrush
Molds (26.3)
- Filamentous fungi
- Hyphae
- Mycellium - Mass of hyphae
Describe Fungal Asexual Reproduction (26.1)
- Offspring are genetically identical to parent
- Three mechanisms
- –i) Binary Fission
- –ii) Budding
- –iii) Spore production
- —–Condidospores (Ex: Aspergillus), Sporangiospores
Describe Fungal Sexual Reproduction (26.1)
- Often occurs under stress or limiting nutrients
- Offspring genetic intermediates of parents
- Haploid cells of opposite mating types fuse
- –Pheromones signal between opposite mating types
- In yeast, mating types are designated as ‘a’ and ‘alpha’
- In other fungi, the hyphae meet and fuse
