Microbiology Exam 2 Flashcards

Chapters 5, 6, 7 and 8

Endosymbiotic Theory

eukaryotic cell evolved when larger prokaryotic cell engulfed smaller prokaryotic cells.

Flagella

-locomotor appendage

-long, cylinder containing microtubules

-covered by an extension of the cell membrane

Cilia

-locomotor appendage

-shorter than flagella

- found only in certain protozoa and animal cells

-function: motility, feeding, filtering

Glycocalyx

- outermost boundary that comes in direct contact w/ the environment

-composed of polysaccharides

-functions: adherence, protection, signal reception

Cell Wall

rigid, provides structural support and shape

Cell Membrane

-bilayer of phospholipids and proteins

-serves as a selectively permeable barrier in transport

-functions in interaction and surface adhesion, secretion, and signal transduction

Nucleus

-most prominent organelle of eukaryotic cell

-nuclear envelope composed of two parallel membranes

-contains chromosomes

Rough Endoplasmic Reticulum (RER)

-function: packaging and transport

Smooth Endoplasmic Reticulum (SER)

-function: nutrient processing, synthesis, lipid storage

Golgi Apparatus

-”central receiving”

-function: modifies, stores, and packages proteins

-composed of flattened sacs called cisternae

Synthesis and Transport Machine

nucleus → RER → Golgi → vesicles → secretion

Lysosomes

-vesicles containing enzymes that came from the Golgi apparatus

-function: intracellular digestion of food particles, protection against invading microbes

Vacuoles

membrane bound sacs that contain particles for digestion, excretion, or storage

Phagosomes

vacuoles merged with a lysosome

Mitochondria

-function: energy production and storage of ATP

Chloroplasts

-function: convert the energy of sunlight into chemical energy through photosynthesis

-found in algae and plants

Ribosomes

-function: protein synthesis

-composed of rRNA and proteins

Cytoskeleton

-function: anchoring of organelles, movement of cytoplasm, amoeboid motion, transport, structural support

Fungi

-unicellular or colonial

-heterotrophic

-parasitic fungi = mycoses

-microscopic:

• hyphae: long filamentous fungi/molds (vegetative: digest/absorb nutrients; reproductive: produce spores)

• yeasts: round ovoid shape, asexual reproduction, have cell wall, lacks locomotor appendages (pseudo hypha: chain of yeasts)

Pneumocystis pneumonia (PCP)

-CA: pneumocystis jiroveci

-Epidemiology: asymptomatic, 30-40% who get it have HIV/AIDS

-Pathogenesis: inhaled spores attach to alveolar walls, they fill with fluid, walls thicken impairing oxygen exchange.

-Symptoms: shortness of breath, slight fever, non-productive cough

-Treatment: trimethoprim sulfamethoxazole (TMP-SMX)

Rose Gardener’s Disease (Sporotrichosis)

-CA: sporothrix schenkii (dimorphic fungi)

-Types:

• cutaneous (skin): most common form, occurs on hand/arm after touching plant

• pulmonary (lung): rare, inhalation of spores

• disseminated (those w/ HIV): infection spreads to another part of the body

-Epidemiology: warmer temp. climates, handlers of thorny plants

-Symptoms: chronic ulcers at site of puncture

-Pathogenesis: spores introduced to wound, pimple develops and enlarges

-Diagnosis: physician obtains swab/biopsy

-Prevention: protective clothing, no vaccine

-Treatment: oral itraconazole (3-6 months); those w/ severity = lipid formulation of amphotericin B, SSKI for cutaneous.

Sporangiospores

formed by successive cleavages called sporangium.

Conidiospores

free spores not enclosed by a sac.

Fungal Identification

-isolation on specific media

-macroscopic and microscopic observation

Roles of Fungi

-adverse:

• mycoses, allergies, toxin production

• destruction of crops and food storages

-beneficial:

• sources of antibiotics, alcohol, organic acids, vitamins

• decomposers of dead plants/animals

• making food

• genetic studies

Valley Fever

-CA: Coccidiodes immitis

-Epidemiology: inhalation of arthrospores, 40% are symptomatic, California/Arizona/S.America,

-Symptoms: resembles TB, coughing, chest pain, fever, weight loss, flu-like, rash

-Pathogenesis: inhalation of spores, tissue damage

-Diagnosis: blood sample, chest x-rays, CT scans, tissue biopsy

-Treatment: clears up on own, oral azoles: ketoconazole (FDA approved), fluconazole (meningitis), IV amphotericin B

Algae

-eukaryotic

-protist

-unicellular, colonial, filamentous

-cell wall

-may or may not have flagella

-photosynthesize w/ chlorophyll

Protozoa

-eukaryotic

-protist

-unicellular

-lack a cell wall

-free living

-heterotrophic

-lack tissues

Algae

-free living

-function: provide basis of food in aquatic habitats, produce oxygen

Protozoa

-have locomotor appendages (flagella, cilia, pseudopods)

-trophozoite: motile feeding stage

-asexual reproduction + sexual reproduction

Giardiasis

-CA: Giardia lamblia

-Facts: lack mitochondria +peroxisomes, has ER, Golgi, cytoskeleton, and flagella, seen by Leeuwenhoek

-Epidemiology: fecal/oral transmission, ingestion of cysts from contaminated water, more prevalent in kids, most frequently diagnosed intestinal parasitic disease in the US.

-Pathogenesis: cysts emerge as trophozoites in colon, attach to bowel, feeds on mucus and reproduce.

-Symptoms: 40% show lactose intolerance, frothy diarrhea, dehydration, weight loss, vitamin deficiencies.

-Treatment: Flagyl (metronidazole), tinidazole, nitazoxanide

-Prevention: boil water, filter water

Malaria

-CA: Plasmodium falciparum

-Epidemiology: “world’s greatest health problem,” 40% are @risk

-Pathogenesis: vector carried (anopheles sp. mosquito), mosquito bites infected person→ picks up gametes → sexual reproduction → bites non-infected person

-Symptoms: flu-like, anemia, jaundice

-Treatment: chloroquinone

Trypanosomes

-pathogenic protozoa

-long, crescent-shaped cell w/ single flagellum

-occur in blood during infection

-transmitted by vectors

Ex:

• T. brucei = african sleeping sickness

• T. cruzi = chagas disease

Entamoeba

-infective amoeba

-Entamoeba histolytica - amebic dysentery

• Symptoms: gastrointestinal disturbances

Parasitic Helminths

-parasitize host tissues

-have mouths for attachment

-have well developed sex organs

• Flatworms

• Roundworms

Robert Koch

-identified pathogens

Friedrich Loeffler and Paul Frosch

-filterable agent cause of certain diseases

Viruses

-obligate intracellular parasites

-need a host

-ultramicroscopic

-do not independently fulfill characteristics of life

-structure: capsid surrounding nucleic acid core

-Genome is either dna OR rna

-lack enzymes and machinery for protein synthesis

Viral Structure

-no resemblance to cells

-capsid

-envelope (not in all viruses)

-nucleic acid molecule (DNA or RNA)

-matrix proteins

-crystalline appearance

Capsids

- all viruses have capsids

• Helical - helix, rod-shaped

• Icosahedral - 3D, symmetrical polygon w/ 20 sides (dice), may/may not have envelope

  • Rotavirus

  • Norovirus

Envelope

-mostly in animal viruses

-spikes: exposed proteins essential for attachment of virus to host cell

-protects the nucleic acid

-dissolves in alcohol

Poxviruses

-atypical virus

-lack capsid and are covered by lipoproteins and fibrils.

-have bacteriophages

Virus Nucleic Acids

-DNA or RNA, never both

-carries genes necessary to invade host cell

-make new viruses

• DNA- ds, ss

• RNA- ss, ds

  • ssRNA ready for translation: postive-sense

  • ssRNA needing conversion: negative-sense

Enzymes for Viral Replication

-polymerases: synthesize DNA or RNA

-replicases: copy RNA

-reverse transcriptcase: synthesis of DNA from RNA

Influenza

-CA: Influenza A and B

-Facts: enveloped polymers of hemagglutinin (HA) and neuraminidase (NA), mutations: antigenic drift [strain in geo. area)/shift [different strain, same host])

-Symptoms: flu-like

-Pathogenesis: kills epithelial cells, HA binds to host cell, NA hydrolisizes mucus releasing new virions

-Epidemiology: adults shed flu virus from the day before symptoms begin, occur during fall/winter months

-Treatment: Tamiflu, Relenza

-Prevention: nasal mist, intramuscular injection

Naming of Viruses

-type

-microscopic appearance

-anatomical/geographic area

-effects on host

-acronyms blending several characteristics

Adsorption

binding of virus to specific molecules on the host cell.

Penetration

genome enters the host cell

Uncoating

the viral nucleic acid is released from the capsid

Synthesis

viral components are produced

Assembly

new viral particles are constructed

Release

assembled viruses are released by budding (exocytosis) or cell lysis

Rabies

-CA: Rabies virus

-Facts: rod-shaped, negative sense linear RNA genome, zoonotic, exposure through bite from rabid animal

-Pathogenesis: virus → bite → neurons → nervous system to brain → rapid replication → salivary glands

-Symptoms: flu-like, weakness, cerebral dysfunction, anxiety, confusion, agitation, delirium, hallucinations

-Prevention: vaccination of pets/people

Fusion

viral envelope fuses directly with host membrane by lipid rearrangement

Endocytosis

entire virus is engulfed in a vacuole.

Where is DNA generally replicated and assembled?

the nucleus

Where is RNA generally replicated and assembled?

the cytoplasm

Cytopathic effects

cell damage altering microscopic appearance

Persistent Infections

-cell harbors the virus and is not lysed.

• herpes simplex virus

• herpes zoster virus

Oncogenic

- animal virus enters host cell and permanently alters its genetic material resulting in cancer

• papillomavirus - cervical cancer

• Epstein-Barr virus - Burkitt’s lymphoma

Bacteriophages

-bacterial viruses (phages)

Steps in Phage Replication

1. Adsorption – binding of virus to specific molecules on
host cell
2. Penetration – genome enters host cell
3. Replication – viral components are produced
4. Assembly – viral components are assembled
5. Maturation – completion of viral formation
6. Lysis & Release 

Lytic Cycle

completion of viral infection through lysis and release of virions

Lysogeny

-spread of the virus without killing the host cell

• Corynebacterium diphtheriae

• vibrio cholerae

• clostridium botulinum

Goals of viral cultivation

1. isolate and identify viruses in clinical specimens

2. prepare viruses for vaccines

3. allow for research on structure and effects

In Vitro

test tubes

• cell (tissue) cultures

In Vivo

alive

• bird embryos

• live animal inoculation

Prions

-misfolded proteins, contain no nucleic acid

-resistant to sterilization

-causes transmissible spongiform encephalopathies

-common in animals

• Creutzfeldt Jakob Syndrome

Microbial Nutrition

process by which chemical compounds are acquired from the environment to sustain life.

Bioelements

basic requirements of life

What are some examples of bioelements?

-carbon

-hydrogen

-oxygen

-phosphorus

-nitrogen

-sodium

-magnesium

Essential nutrients

substance an organism must get from a source outside its cells

Macronutrients

-required for large amounts (macro)

-plays a role in cell structure and metabolism

• ex: proteins, carbohydrates

Micronutrients

-required for small amounts (micro)

-involved in enzyme function and protein structure maintenance

• ex: manganese, zinc, nickel

What is an example of organic nutrients?

(must contain carbon and hydrogen atoms)

-methane

-carbohydrates

-lipids

-proteins

-nucleic acids

What is an example of inorganic nutrients?

(combo of atoms that are NOT carbon and hydrogen)

-magnesium sulfate

-sodium phosphate

-O2

-CO2

-H2O

What are the six compounds found in organic compounds?

1. carbon

2. hydrogen

3. oxygen

4. phosphorus

5. sulfur

6. nitrogen

Which macromolecule is most prevalent in the cell?

proteins

Heterotrophs

must obtain carbon in an organic form made from other living organisms

Autotrophs

organism uses CO2 as its carbon source

Why can’t organic compounds be synthesized by an organism?

they lack the genetic and metabolic mechanisms to synthesize them.

Chemotroph

gain energy from chemical compounds

Phototrophs

gain energy through photosynthesis

Photoautotrophs

1.oxygenic photosynthesis

-produces O2

-chlorophyll is the primary pigment

• ex: plants, algae, cyanobacteria

2.anoxygenic photosynthesis

-production of sulfur

-bacteriochlorophyll is the pigment

• ex: purple/green sulfur bacteria

Chemoautotrophs (lithoautotrophs)

survive only on inorganic substances

• ex: Venenvibrio

What chemoautotroph produces methane gas under anaerobic conditions?

methanogens

• ex: Methanocaidococcus jannaschii

Saprobes

-heterotroph

-free living microorganisms that feed on organic detritus from dead organisms

• ex: opportunistic pathogens, facultative parasites

Symbionts

-heterotroph

-obtains nutrients from living or nonliving source

• ex: obligate parasites

Passive Transport

-doesn’t require energy

-higher concentration → lower concentration

• diffusion

• osmosis - diffusion of H2O

• facilitated diffusion - solutes requiring a carrier

Active Transport

-requires energy and carrier proteins

-gradient independent

• carrier-mediated active transport

• group translocation

• bulk transport - endo/exo/pino cytosis

Isotonic Solution

water concentration is equal inside and outside the cell

Hypotonic

net diffusion of water into the cell

Hypertonic

-water diffuses out of the cell

-shrinkage if the cell membrane (plasmolysis)

What does it mean for carriers proteins to exhibit specificity?

they bind and transport only a single type of molecule

What does it mean for facilitated diffusion to exhibit saturation?

the rate if transport limited by the number of binding sites on transport proteins

Carrier-Mediated Active Transport

1.membrane-bound transport proteins interact w/ solute-binding proteins

2.ATP is activated and generates energy to pump solute into the cell.

Endocytosis

bringing substances into the cell through a vesicle/phagosome

Phagocytosis

ingests substances or cells (pseudopods)

Pinocytosis

ingests fluids and/or dissolved substances (microvilli)