A&P #6

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A&P #6
2012-03-10 10:48:06

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  1. describe the prokaryotic cell surface structures & features
    • cell wall: provides shape & stability, contains peptidoglycan(immense, covalently-linked molecule), large polymer resembling a chain link fence, many antibiotics target the cell wall(ex: penicillins)
    • cell membrane: regulates transport of material in & out of cell, it's a biphospholipid membrane
  2. identify the primary shapes & arrangements of prokarotic bacterial cells
  3. bacteria come in 3 major shapes or morphological types: 1st- cocci(sperical bacterial cells), 2nd- bacilli(rod-shaped bacteria-hotdog) some are in between cocci & bacilli(they are oval in shape) and referred to as coccobacilli, (others look like a comma-shape) called vibrios, 3rd- 2 sub-groups(long, thin, coiled, rod-shaped): spirillia (loosely coiled or wavy) & spirochetes (non-rigid, tightly coiled, corkscrew-shaped rods)
  4. define CAPSULE
    protective structure that serves as a defense mechanism
  5. describe the basic cell components of the prokaryotic cell
    cell structures: cytoplasm(primarily water w/ carbs, lipids, & enzymes), ribosomes(protein synthesis centers), nucleoid(chromosome), inclusion bodies(store molecules essential to cell function), some prokaryotes- secrete a capsule(contributes to pathogenicity) & have plasmids(extrachromosomal DNA important for transfer of genetic material)
  6. define PLASMIDS
    self-replicating extrachromosomal DNA that carry one or more pieces of genetic information, not required to sustain life
  7. describe taxonomy of the prokaryotic cell
    all living cells are divided into 5 kingdoms and are classified as either prokaryotes or eukaryotes, the prokaryotes belong to the Kingdom Monera and consist (all the single-celled prokaryons) of the bacteria and cyanobacteria (blue green algae)
  8. define GRAM STAIN
    • (determine thick or thin wall) method groups medically important bacteria into 2 categories:
    • gram-positive- thick, peptidoglycan-rich cell wall that also contains teichoic acid, causes retention of crystal violet (blue) dye
    • gram-negative- thin peptidoglycan cell wall & a lipoprotein-rich cell membrane, releases crystal violet dye when rinsed with alcohol, the safranin (pink) counterstain is retained
  9. describe the size of the prokaryotic cell
    they inhabit nearly everywhere, among the smallest organisms- average size range of bacteria are 0.5-2.0 microns (compared to blood cells- 7.5) despite small size they have maximum surface area for absorption of nutrients
  10. a little more on COCCI
    • spherical, non-motile bacteria
    • subcategories: diplo(pair), strepto(chain), staphylo(irregular cluster), tetra(group of four)
    store molecules essential to cell function such as glycogen
  12. what are the 3 types of CULTURE MEDIA?
    • enriched
    • selective
    • differential
  13. describe ENRICHED MEDIA and give examples
    • contains substances that bacteria love
    • encourages growth of most bacteria
    • ex: sheep blood agar & chocolate agar
  14. describe SELECTIVE MEDIA and give an example
    • contains inhibitor
    • allows certain types of bacteria to grow and inhibits others
    • ex: MacConkey agar
  15. describe DIFFERENTIAL MEDIA and give an example
    • roughly groups bacteria based on fermentation of carbohydrates
    • ex: MacConkey agar
  16. describe AEROBES
    • require atmospheric oxygen
    • exs: streptococcus, staphylococcus, & E. coli
  17. describe ANAEROBES
    • require NO oxygen
    • ex: clostridium species (cause disorders such as: gangrene, botulism, & tetanus)
  18. describe MICROAEROPHILS
    • require decreased oxygen, increased CO2
    • ex: Campylobacter (causes intestinal disorders)
    process of cell division in bacteria
  20. T/F bacterial cells DO NOT have a cell cycle
    TRUE, they are continuously dividing & replicating their DNA
  21. what are the 4 PHASES OF CELL DIVISION?
    • LAG phase
    • LOG phase
    • STATIONARY phase
    • DECLINE (DEATH) phase
  22. describe LAG PHASE
    • GEAR UP phase
    • not greatly increaseing in #
    • metabolically active
    • growing, synthesizing enzymes, & producing large amounts of ATP
  23. describe LOG PHASE
    • period of rapid, exponential growth
    • GENERATION TIME- bacteria will DOUBLE
  24. describe STATIONARY PHASE
    • when # of new cells produced is same as # of cells dying
    • cells are running out of nutrients
  25. describe DECLINE (DEATH) PHASE
    # cells dying is GREATER than # new cells
  26. define SYMBIOSIS
    • "LIVING TOGETHER" (bacteria)
    • forms 3 different relationships:
    • mutalism
    • parasitism
    • commensalism
  27. describe MUTALISM
    both members benefit (ex: E. coli, living in large intestine- nice, warm environment for bacteria & humans benefit from Vitamin K that E coli. produces & vitamin K is essential for clotting process)
  28. describe PARASITISM
    one organism benefits from the relationship & other is harmed (ex: malaria, & tapeworms)
  29. describe COMMENSALISM
    one organism benefits & other neither benefits or is harmed (neutral) (ex: many bacteria that live on our skin- they benefit from nice, warm environment and human (host) is NOT harmed)
  30. describe the role of NORMAL FLORA (aka RESIDENT FLORA)
    • microflora using secretions of the host as nutritional sources
    • present (live) in or on body, but don't cause disease (commensals)
    • exs: skin, hair, Conjunctiva, mouth, nose, throat, urinary, reproductive and GI tracts
  31. describe the role of TRANSIENT MICROFLORA
    • "come & go" organisms
    • exist in same areas occupied by resident flora
    • may become OPPORTUNISTS
  32. define PATHOGENICITY
    cause disease (invade host, multiply, & avoid damage from host's defense)
  33. define VIRULENCE
    • strength (intensity of bacterial & other microbial infections)
    • varies greatly in organisms, but is always factor in infections
  34. what are the 3 SPECIFIC PATHOGENIC MECHANISMS of bacteria & describe?
    • adherence - pili to cling to surface of host, multiply, & form colonies
    • colonization - once in place, bacterial replication forms colonies, may overcome host's defenses
    • formation of a capsule - helps organisms resist host defense processes
  35. define INVASIVENESS
    ability of organisms to penetrate host tissue, ususally via special enzyme
  36. what are some examples of enzymes contributing to invasiveness and pathogenicity?
    • hyaluronidase - aka spreading factor, produced by streptococci, staphylococci, & other pathogens
    • attacks hyaluronic acid, which is the interstitial cement ("ground substance") of connective tissue
    • coagulase - produced by some bacteria that accelerates clotting of blood, often providing protection from host defenses leading to abscess formation
    • species of staphylococcus produce this enzyme
    • streptokinase & staphylokinase - produced by pathogenic streptococci & staphylococci, respectively
    • kinase enzymes digest fibrin & prevent clotting of blood
    • resulting reduction of fibrin allows more rapid diffusion of infectious bacteria into host tissue
    • streptococcus strain of "flesh eating bacteria" produces streptokinase
  37. describe EXOTOXINS
    • very powerful toxins
    • screted by living bacterial cell (mostly from GRAM POSITIVE species)
    • causes: botulism, gas gangrene, tetanus, & staphylococcal food poisoning
  38. describe ENDOTOXINS
    • found primarily in GRAM NEGATIVE bacteria
    • released only when organism dies
    • cause non-specific GI symptoms (exs: diarrhea, cramping, generalized malaise)
    • associated w/ cholera, some types of salmonella, other similar types toxin-associated bacterial food or water-borne infections
  39. define GERMINATION
    spores are dormant
  40. define ENDOSPORE
    • dormant stage of some bacteria
    • form when nutritional & environmental conditions are unfavorable for growth
    • survival under harsh conditions (excessive cold, heat, or dryness)
    • revert to active cells under favorable conditions
  41. list diseases caused by spore-forming bacteria
    clostridia species that cause tetanus, botulism, gas gangrene
  42. describe TRANSDUCTION
    • during transduction, asexual genetic process viruses called bacteriophages, or simply phages transfer genes between mating bacteria
    • (process uses a bacteriophage to insert the resistant DNA into the bacterium)
  43. bacteria can exchange genetic material through which 3 different mechanisms?
    • transformation
    • transduction
    • conjugation
  44. describe TRANSFORMATION
    • when bacterium dies, fragments of its DNA are taken up by neighboring bacteria (picking up left behind fragments)
    • not all bacteria have the ability to take in pieces & parts from other bacteria
  45. describe CONJUGATION ("bacterial sex")
    • requires contact between 2 bacteria
    • utilizes a plasmid (extrachromosomal DNA, not required by bacterium)
    • transfers a greater amount of DNA than transformation or transduction
  46. define PLASMIDS
    • extrachromosomal DNA in cytoplasm of some bacteria
    • bacteria often develop their drug resistance through plasmids, aka resistance transfer factors
    (by transduction, transformation, & conjugation) transfers DNA leading to new strains of bacterium including antibiotic resistant strains
  48. define ANTIMICROBIAL
    agents include substances used to specifically treat infectious microbial diseases
  49. define ANTIBIOTICS
    antimicrobial agents containing substances derived from other organisms
    • antimicrobials can be either broad spectrum or narrow spectrum
    • broad- are affective agains a wide range of microorganisms including both gram positive & negative bacteria
    • narrow- are effective against a limited # of microorganisms or a single taxonomic group (ex: use of penicillin to treat streptococcal pharyngitis)
    inhibits organism growth
  52. define BACTERIOCIDAL
    kills the organism
  53. give examples of how bacteria become resistant to antibiotics
    • resistance to antibiotics increases each year
    • resistance occurs through:
    • overuse of antibiotics
    • plasmids
    • genetic transfer mechanisms
    • development of neutralizing enzymes
    • alteration of pathways used by antibiotic
    • altering cell membrane permeability
  54. briefly describe basic principle of agar disc diffusion laboratory test for determining antimicrobial effectiveness
    • uses paper discs impregnated w/ specific concentration of antimicrobial to be tested
    • results are reported as sensitive, intermediate, or resistant
  55. Commonly encountered bacterial infections: UPPER RESPIRATORY TRACT (above larynx) INFECTIONS
    • pharyngitis- strep throat caused by streptococcus pyogenes
    • other bacterial infections invade ears, eyes, sinuses, & upper bronchioles
  56. Commonly encountered bacterial infections: LOWER RESPIRATORY TRACT INFECTIONS
    • pneumonias
    • top 3 & all contain a capsule virulence factor:
    • haemophilus influenzae
    • klebsiella pneumoniae
    • streptococcus pneumoniae (most common)
  57. Commonly encountered bacterial infections: GASTROINTESTINAL BACTERIAL
    • contaminate food or water
    • exs:
    • salmonella
    • shigella (severe diarrhea)
    • staphylococcus aureus (clusters)
    • E. coli O157:H7
  58. Commonly encountered bacterial infections: NERVOUS SYSTEM
    • meningitis
    • exs: Haemophilus influenzae (children)
    • Neisseria meningitidis (young adults)
    • vaccines are available for both
    • botulism (clostridium botulinum)
    • tetanus (clostridium tetani)
    • toxic shock syndrome (staphylococcus aureus)
  60. describe the nature of CHLAMYDIA
    • obligate intracellular organisms (require eukaryotic host for replication)
    • most common STD in US
    • chlamydia trachomatis causes a variety of human infections including:
    • trachoma (eye infection that may lead to blindness
    • sexually transmitted disease causing pelvic inflammatory disease (PID, in women) & urethritis (in males)
    • conjunctivitis in newborns acquired during birthing process
  61. define PLEOMORPHIC
    assume many different shapes
  62. describe the nature of RICKSETTSIAS
    • obligate intracellular parasite (require eukaryotic host for replication)
    • transmitted by a vector
    • transmitted to humans through bite of the vector
    • Rocky Mountain Spotted fever is a systemic disease that is common in many states in US (carrie by ticks)
    • other diseases include: malaria & rabies
  63. describe the nature of MYCOPLASMAS
    • tiniest free-living organisms
    • DO NOT have a cell wall- PLEOMORPHIC (assume many diff shapes)
    • mycoplasma pneumoniae (causes primary atypical (walking) pneumonia
    organisms requiring a eukaryotic host cell for replication
  65. give examples of arthropod vectors that RICKSETTSIA inhabit
    ticks, lice, fleas
  66. general considerations of viruses
    • obligate intracellular parasites
    • often use host's nucleic acid machinery for replication of the viral genome
    • over 1/2 of all human infection processes are due to viruses
  67. viral classification
    • in general viruses are broadly classified as either RNA or DNA (NOT BOTH) viruses- based on their make-up of their genome
    • RNA viruses also contain code for reverse transcriptase (enzyme that makes DNA from RNA)
    • nucleic acid (RNA or DNA)
    • capsid- protective coat enveloping the nucleic acid & determines shape of virus
    • envelope- present in some viruses & may have glycoprotein spikes (determine host cell specificity & may hide virus from host's immune system)
  69. define CAPSOMERES
    individual protein subunits of capsids
  70. define NUCLEOCAPSID
    combined capsid/nucleic acid arrangement
  71. describe VIRAL ENVELOPE
    are external to the capsid & are acquired from combos of proteins, lipids, & carbs found in cell membrane of the host cell
  72. define SPIKES
    • projections, usually glycoprotein molecules that attach to specific sites on the host cell wall
    • account for the high degree of both host & host cell, specificity of viruses
    • may serve to "hide" the virus from being attacked by host's immune system
  73. describe the 5 steps in VIRAL REPLICATION (KNOW ORDER)
    • 1.ADSORPTION- attachment of virus to host cell
    • 2.PENETRATION- virus enters the host cell (through endocytosis or fusion) & uncoats (takes off its envelope & capsid)
    • 3.SYNTHESIS- utilizes host nucleus to make new genetic material
    • 4.MATURATION- virus is packaged into new complete virons
    • 5.RELEASE- departure of new virons from host cell (host cell may ru[ture or host cell remains intact & releases the virus)
  74. define VIRION
    single, complete virus unit
    • viral infections fall into 2 main categories:
    • acute infections- disease cycle is relatively short, host cell ruptures & virus spreads to neighboring cells (common cold(rhinovirus), influenza( types A & B), some hepatitis viruses)
    • latent/ persistent infections (reappear)- virus becomes relatively inactive but reemerges, provirus remains in host cell, replicates new virions when triggered by some external event (stress, fever, etc.) (herpes virus, epstein-barr virus (mono), HIV)
    • immune system viruses (epstein-barr, HIV)
    • oncogenic viruses (possess oncogenes(cancer-causing genes) that cause uncontrolled & abnormal division of host cells by altering cell cycle "checkpoints" (hep B, hep C, & human papilloma virus)
  77. treatment of VIRAL INFECTIONS
    • antibiotics are INEFFECTIVE
    • antiviral drugs- slow down attachment of virus to host cell, suppress-DO NOT cure-viral infection
    • vaccines- salk-sabin (polio), gardisil (human Papilloma virs-->cervical cancer), & hepatitis A, Heptovax (hepatitis B)
  78. define & describe PRIONS
    • name is derived from proteinaceous infectious particle
    • ALL known prion diseases affect cells of the brain
    • infectious proteins w/out genetic material that come into contact w/ normal proteins & transform them into more infectious prions
    • current collective terminology for prion diseases
    • microscopic holes in the brain- looks like a "sponge"
  80. characteristics of PRIONS
    • generally resistant to inactivation by heating to 90 degrees, temp that will inactivate almost all viruses
    • infection is resistant to radiation treatments which inactivate organisms w/ genomes
    • NOT susceptible to enzymes that inactivate RNA & DNA
    • susceptible to protein denaturing agents
  81. diseases caused by PRIONS
    • bovine spongiform encephalopathy (BSE, aka MAD COW disease)- causes slow loss of neural function & eventual death
    • Creutzfeldt-Jakob disease (human disease is a variation)- slow neural degenerative disease, resulting in eventual death
    • scrapie (in sheep)
    • chronic wasting disease (deer & elk)
  82. general concepts of FUNGI
    • diverse group of heterotrophic organisms
    • importan for the decomposition & recycling of organic material
    • divided into 2 groups: yeasts & molds
    • examples: Candida albicans (yeast infection) & tinea corporis (ringworm, mold)
  83. name the 5 kingdoms
    • protista
    • animalia
    • monera
    • fungi
    • plantae
  84. parasitic organisms
    protozoa (single-celled- from kingdom protista) & helminths (multi-cellular- from kingdom animalia)- live @ expense of the host, transmitted to humans by vectors (biological-mosquito transmitting malaria or mechanical-transmission of parasite eggs to food by flies & other insects)
  85. describe PROTOZOA
    • single-celled organisms
    • trophozoite stage- which is the motile, invasive form of the organism- infective stage
    • cyst stage- which allows organism to survive in dormant state in the external environment
  86. examples of common protozoans pathogenic for humans
    • 1. Giardia Lamblia- ingesting cysts from animal contaminated water, intense GI distress & diarrhea
    • 2. Cryptosporidium- self limiting GI symptoms, if infected can become a carrier, recently associated w/ recreational water use
    • 3. Plasmodium- causes malaria, 350-500 million cases/year worlwide(over million deaths, primarily in African children) humans are intermediary hosts, organism invades RBCs
  87. describe HELMINTHS
    • parasitic worms
    • hosts are either:
    • definitive- harbor parasite when it reproduces
    • intermediate- harbor parasite during a developmental stage in the parasite's life cycle
    • accidental- not partof the normal life cycle
    • they come in 4 groups:
    • flukes, tapeworms, roundworms, and tissue parasites
  88. describe TAPEWORMS
    • segmented worms that contain a head (scolex) & many segments called proglottids
    • hermaphroditic- contain both ovaries & testes
    • infective stage is larvae found in cattle and swine
    • most prevalent- beef & pork (taenia), fish (dibothrocephalus)
    • several cm to meters in length
  89. describe ROUNDWORMS
    • live in lumen of intestinal tract
    • infection occurs by ingestion of egg or by penetration of the skin by the larvae- pinworms (enterobius), ascarids, & hookworms