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Microbiology Test #1

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by: Allison Collins

Microbiology Test #1 BIOL 2230

Allison Collins
GPA 3.88

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About this Document

These notes cover the material on our first exam. I've highlighted important terms and concepts and drawn supplemental diagrams. Good luck!
Anthony L Newsome
Study Guide
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1 review
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"Clutch. So clutch. Thank you sooo much Allison!!! Thanks so much for your help! Needed it bad lol"
America Gulgowski Jr.

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This 18 page Study Guide was uploaded by Allison Collins on Sunday February 14, 2016. The Study Guide belongs to BIOL 2230 at Middle Tennessee State University taught by Anthony L Newsome in Fall 2015. Since its upload, it has received 115 views. For similar materials see Microbiology in Biology at Middle Tennessee State University.


Reviews for Microbiology Test #1

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Clutch. So clutch. Thank you sooo much Allison!!! Thanks so much for your help! Needed it bad lol

-America Gulgowski Jr.


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Date Created: 02/14/16
MICROBIOLOGY  UNIT  1  TEST     Highlight  =  important  term                  Highlight  =  important  concept                   Highlight  =  important  person  or  specific  organism     History  and  general  principles  of  antibiotics     Eukaryotes  –  humans,  plants,  protozoa,  algae   Prokaryotes  –  bacteria  ONLY   All  cells  –  contain  nucleic  acids,  lipids,  proteins,  polysaccharides   Viruses  –  not  cells  –  live  inside  eukaryotes  or  prokaryotes   •   Have  no  metabolism  outside  host  cell   •   Referred  to  as  a  viral  AGENT  –  not  a  viral  CELL     Timeline     1600s  –  Leeuwenhoek  invented  microscopes   1860s     •   Scientists  asking:  where  do  bacteria  come  from?  –  by  this  point  they  understood  that  it   is  not  by  spontaneous  generation  (idea  that  life  can  form  spontaneously)   Louis  Pasteur  –  disproved  spontaneous  generation  (including  bacteria)   •   Experiment:  took  2  sterile  flasks  containing  broth   o   Exposed  one  flask  to  air  –  microorganisms  grew   o   Did  not  expose  the  other  flask  to  air  –  no  microorganisms  grew   •   Pasteurization  –  process  of  mild  heating  to  kill  microorganisms  that  make  things   susceptible  to  spoilage   o   Heated  at  70C/160F   1870s     •   Scientists  also  asking:  can  bacteria  make  people  sick?   Robert  Koch  –  creator  of  Koch’s  Postulates   o   Still  a  cornerstone  of  microbiology   o   Demonstrated  that  a  specific  disease  can  be  caused  by  a  specific  microorganism   o   Established  set  of  criteria  that  must  be  met  before  specific  disease  is  said  to  be   caused  by  an  infectious  agent   •   Koch’s  Postulates   1.   Suspected  pathogenic  organism  should  be  present  in  ALL  CASES  of  the  disease  and   absent  from  healthy  animals.   2.   Suspected  organism  should  be  grown  in  a  pure  culture.     3.   Cells  from  the  pure  culture  of  the  suspected  organism  should  cause  disease  in  a   healthy  animal.   4.   The  organism  should  be  re-­‐isolated  and  shown  to  be  the  same  as  the  original   organism.   Late  1800s   •   Had  been  established  that  microorganisms  can  cause  disease   o   This  begs  the  question:  can  we  reduce  human  illness  by  killing  microorganisms?   Joseph  Lister  –  applied  the  concept  of  disease-­‐causing  bacteria  to  surgery/post-­‐surgical   infections   •   Soaked  surgical  instruments  in  phenol,  which  greatly  reduced  the  number  of  post-­‐ surgical  infections   Next  question  –  can  microorganisms  already  in  the  body  be  killed,  thus  killing  the  disease?   Paul  Erlich  –  found  that  arsenic  will  kill  syphillus  bacteria  but  also  makes  people  ill   o   Thus  the  advent  of  the  chemotherapeutic  agent  –  a  chemical  with  therapeutic  value   Late  1930s   •   “Antibiotics”  not  a  term   •   Sulfa  drugs  were  used,  but  were  not  referred  to  as  antibiotics   o   Sulfa  drugs  inhibit  growth  of  folic  acid,  which  bacteria  need  to  grow   •   World  War  II  –  “antibiotics”  still  not  a  term   o   Penicillin  packets  poured  on  wounds  at  D-­‐Day   Alexander  Fleming  –  discovered  Penicillin  on  accident   •   Was  growing  bacteria  on  agar  plate,  which  unexpectedly  grew  a  green  fuzzy  material   after  several  weeks   •   Where  the  fuzz  existed,  there  was  no  bacteria   •   Learned  that  the  fuzz  was  a  common  food  mold  called  Penicillium   •   Active  chemical  was  termed  Penicillin   1950s   •   Antibiotics  were  thought  of  as  miracle  drugs   •   At  the  end  of  WWII,  they  became  available  to  civilians     General  principles  of  antibiotics   2  states  of  bacteria   •   Vegetative  –  when  eating,  multiplying,  or  metabolizing   •   Spore/dormant  (only  some  bacteria)  –  when  exposed  to  unfavorable  conditions   o   Metabolically  inactive   o   Come  out  of  dormancy  once  conditions  are  favorable  again  –  dormancy  can  last   for  thousands  of  years     Antibiotic  –  a  metabolite  produced  by  one  microorganism  that  inhibits  a  specific  metabolic   pathway  in  another  microorganism   •   This  is  a  microorganism’s  way  of  killing  a  competing  microorganism  for  self-­‐preservation     Types  of  antibiotics     •   Inhibition  of  bacteria’s  cell  wall  synthesis   •   Inhibition  of  bacteria’s  DNA  synthesis   •   Inhibition  of  bacteria’s  protein  synthesis   •   Inhibition  of  bacteria’s  metabolism     Most  biomass  on  earth  is  microbial   •   Most  prokaryotes  reside  underground  in  the  oceanic  and  terrestrial  subsurfaces  –  many   of  these  are  unexplored   o   This  may  be  the  answer  to  formulating  new  antibiotics  when  diseases  become   resistant  to  current  antibiotics   Microorganisms  can  be  both  beneficial  and  harmful  to  humans   •   We  tend  to  emphasize  harmful  microorganisms  (i.e.  pathogens),  but  the  vast  majority  of   microorganisms  in  nature  are  beneficial     The  prokaryotic  cell  in  detail     Distinguishing  features  of  eukaryotic  cells  (everything  but  bacteria)   •   Nucleus  –  set  of  parallel  membranes  that  contain  chromosomes  (23  pairs  in  humans)   o   DNA  is  linear   o   DNA  is  wrapped  around  histones  (proteins)   o   50%  of  DNA  from  each  parent   §   Maternally  inherited  DNA  shows  a  clear  family  history  that  has  only  been   altered  by  chance  mutations   •   Mitochondria  –  site  of  ATP  (energy)  production   o   Has  its  own  DNA     o   All  mitochondria  come  from  the  mother   o   Multiplies  in  cells  depending  on  how  much  energy  a  cell  needs   o   Cells  vary  in  number  of  mitochondria  they  possess     •    Membrane-­‐bound  organelles     Distinguishing  features  of  prokaryotic  cells  (bacteria)   •   DNA  is  not  enclosed  in  membrane-­‐bound  nucleus   •   DNA  circular,  not  linear   •   DNA  is  not  wrapped  around  histones   •   Almost  always  have  cell  walls  composed  of  peptidoglycan   o   This  is  of  great  medical  importance   o   Human  cells  do  not  contain  peptidoglycan,  so  substances  that  inhibit   peptidoglycan  synthesis  harm  bacteria  but  not  human  cells   §   E.g.  Penicillin   •   Has  plasmids  –  circular  DNA  outside  of  chromosomes   o   Antibiotic  resistance  is  often  transferred  by  plasmids     External  to  cell  wall  of  bacteria   §   Capsule/slime  layer/glycocalyx   §   Not  all  bacteria   §   In  order  for  bacteria  to  cause  disease,  it  must  be  able  to  stick  to  your   tissue   •   Ex:  cough,  diarrhea,  UTI  –  body  attempts  to  expel  bacteria   §   A  very  thick  capsule  makes  an  infection  more  difficult  to  treat   •   For  antibiotics  to  inhibit  cell  wall  formation,  protein  synthesis,   etc.,  must  be  able  to  get  into  bacteria   §   The  capsule  is  what  interacts  with  your  immune  system   •   Vaccine  production  is  geared  at  injecting  capsule  of  the  bacteria   into  your  body  so  that  your  immune  system  creates  antibodies  to   it   •   Capsule  vaccine  candidates  –  create  vaccines  with  purpose  of   inhibiting  capsule’s  ability  to  adhere  to  mucus   o   Flagella     §   Not  all  bacteria   §   Long  hair-­‐like  projection   §   May  be  just  one  or  multiple   §   Enable  movement   §   Flagella  vaccine  candidates  –  create  vaccines  with  purpose  of  inhibiting   flagella’s  ability  to  adhere  to  mucus   o   Fimbriae   §   Not  all  bacteria   §   Fine  hairlike  structures  that  aid  in  attachment   §   Ex:  Streptococcus  mutans   •   Adheres  to  tooth  enamel  with  its  fimbriae   •   When  the  bacteria  metabolize  sugar,  create  acid  that  creates  hole   in  enamel  à  cavity   §   Ex:  Neisseria  gonorrhoeae   •   Uses  fimbriae  to  attach  to  urinary  tract   o   Pili     §   Not  all  bacteria  have  them   §   Hairlike  structures,  longer  than  fimbriae/shorter  than  flagella   §   Promote  exchange  of  plasmids     §   Possible  prevention  of  major  diseases  is  to  inhibit  the  production  of   capsule,  flagella,  fimbriae,  pili   o   Lipopolysaccharide  (LPS)     §   Molecule  extremely  important  to  human  health   §   Found  only  in  gram-­‐negative  bacteria   §   Toxic  to  animals  –  especially  humans   §   Pyrogenic  compound  –  causes  fever,  septic  shock,  cell  constriction   •   Ex:  syringe  packaging  says  “non-­‐pyrogenic”  –  means  it  has  been   tested  for  LPS   §   Also  referred  to  as  an  endotoxin   •   Actively  releases  toxins  into  environment  (e.g.  tetanus,  botulism)   §   LPS  can  be  shed  by  bacteria  –  released  into  environment  –  especially   when  bacteria  die   §   Once  LPS  is  in  circulatory  system,  there’s  no  way  to  get  rid  of  it   •   Can’t  be  destroyed  –  can  only  treat  symptoms   §   Anything  put  into  the  body  must  be  tested  for  LPS   •   Use  Limulus  amoebocyte  lystate  assay  (LAL)  to  test  for  presence   of  LPS  –  causes  gel  to  form  around  bacteria  with  LPS   §   Sometimes  treatment  of  bacteria  with  LPS  does  not  involve  killing  the   bacteria  because  when  the  cell  dies  all  LPS  will  be  released  into  the  body     Prokaryotic  cell  wall   §   Composed  of  peptidoglycan,  which  is  a  polymer  –  anything  composed  of  repeating   subunits   §   Composed  of  2  sugar  derivatives  and  4  different  amino  acids   o   Sugars:  N-­‐Acetylglucosamine  M  (NAM)  and  N-­‐Acetylmuramic  acid  (NAG)     Gram-­‐positive  bacteria     §   Have  a  thick  layer  of  peptidoglycan  in  cell  wall     o   Consists  of  alternating  NAM  &  NAG   o   Peptidoglycan  retains  violet  stain  from  Gram  test   §   More  receptive  to  antibiotics  than  gram-­‐negative  because  they  have  no  outer   membrane   §   Also  have  teichoic  acids   §   So  from  outside  to  inside:  teichoic  acids  à  thick  pep.  layer  à  thin  plasma  membrane   Gram-­‐negative  bacteria     §   Have  a  thin  layer  of  peptidoglycan  in  cell  wall     §   Have  a  thick  plasma  membrane   §   From  outside  to  inside:  thick  plasma  membrane  containing  LPS  à  thin  pep.  layer  à   thick  inner  plasma  membrane   §   Turns  pink  after  Gram  test   Gram  stain  –  traditionally  has  4  steps   1)   Crystal  violet,  2)  Gram’s  iodine,  3)  ethanol,  4)  saffron     Damage  to  bacterial  cell  walls  is  an  extremely  important  concept  in  the  treatment  of  bacterial   infections   §   Peptidoglycan  inhibitors  do  not  damage  eukaryotic  cells,  as  they  do  not  contain   peptidoglycan     Some  medically  important  bacteria  lack  a  cell  wall     §   Mycoplasm  pneumonia  –  common  in  young  children   §   Chylamidia  pneumonia  –  common  in  young  adults   §   Penicillin  would  have  no  effect  on  these     Cell  membrane   §   2-­‐layered  structure  composed  primarily  of  lipids  and  proteins   §   Surrounds  cell  –  if  broken,  cell  may  die   §   Basically  same  structure  in  prokaryotic  and  eukaryotic  cells,  but  eukaryotic  cell   membranes  have  sterols,  which  make  it  more  rigid   o   Eukaryotic  cells  are  larger  and  have  membranes  more  prone  to  bursting,  like  a   full  water  balloon   §   Phospholipid  bilayer  -­‐  each  layer  is  composed  of  repeating  structures  with  polar  head   (made  of  phosphate  and  glycerol)  and  2  nonpolar  fatty  acid  tails   o   The  heads  are  polar  and  thus  are  hydrophilic  (seek  out  water)   o   2  fatty  acid  tails  attached  to  head  –  are  nonpolar  and  thus  hydrophobic  (avoid   water)   §   The  hydrophilic  heads  orient  themselves  to  the  outside  of  the  cells,  where  water  is   §   Interspersed  throughout  the  membrane  are  integral  and  structural  proteins       In  order  for  a  drug  to  work,  it  must  get  through  the  plasma  membrane   §   Group  translocation  –  substance  is  chemically  altered  in  passage  across  the  membrane   o   A  phosphate  is  usually  added  to  it   §   Active  transport  –  compound  enters  cell  unchanged   §   If  a  drug  is  chemically  changed  when  passing  through  the  membrane,  it  may  be   ineffective  once  inside  the  cell   o   However,  sometimes  a  chemical  change  is  beneficial     Ideal  cancer  drug  –  nontoxic  but  adheres  to  cancer  cells  (nonexistent  so  far)     Bacterial  DNA  is  a  singular  circular  chromosome   §   500x  longer  than  cell  but  has  no  histone  proteins   §   DNA  is  supercoiled     Ribosomes   §   Site  of  protein  synthesis   §   Differ  in  size  from  eukaryotic  cells   §   Some  antibiotics  function  in  attaching  to  the  end  of  a  ribosome,  thus  inhibiting  protein   synthesis   Plasmids  –  circular,  extrachromosomal  DNA   Endospore  -­‐  highly  resistant  differentiated  bacterial  cell  produced  by  certain  gram-­‐positive   bacteria     Important  spore-­‐forming  bacteria   Clostridium  tetani   §   Causes  tetanus  –  releases  toxin  that  keeps  muscles  from  relaxing  (AKA  tetany)  –  lockjaw   §   C.  tetani  spores  can  only  multiply  in  absence  of  oxygen  –  i.e.  they  are  anaerobic   §   Rusty  nail  has  spores  on  its  surface,  but  they  can’t  germinate  until  they  enter  a  deep   puncture  wound   o   Other  bacteria  in  the  wound  are  aerobic  and  use  up  the  present  oxygen,  making   a  favorable  environment  for  the  anaerobic  C.  tetani  spores   Clostridium  botulinum     §   Produces  toxins  that  prevent  muscles  from  contracting  (flaccid  paralysis)   §   Can  cause  food  poisoning   o   Improperly  canned  foods   o   When  aerobic  bacteria  use  up  the  present  oxygen,  the  anaerobic  spores  can  now   germinate   §   Less  likely  in  acidic  foods   §   Honey  causes  botulism  in  infants   o   Adults  have  trillions  of  flora  in  intestines  that  overpower  spores  –  prevent   germination   o   Infants  do  not  have  that  flora,  so  C.  botulinum  causes  flaccid  paralysis  -­‐   suffocation   o   SIDS  –  unknown  cause   o   In  a  few  cases  have  been  able  to  culture  C.  botulinum  in  fecal  sample   §   Botox  –  causes  facial  muscles  to  relax     o   Too  much  can  cause  facial  drooping   Bacillus  anthracis   §   Causes  anthrax   §   Aerobic  bacteria   §   When  airborne,  is  breathed  in  à  spores  germinate  in  lungs   §   Biological  weapon  fears     Cell  chemistry     Microorganisms  are  70%-­‐90%  water   55%  protein,  20%  RNA   Rest  is  made  of  lipids,  polysaccharides,  lipopolysaccharides,  DNA     4  classes  of  molecules  in  bacteria       Simple  sugars   §   Monomeric  (simple)  constituents  of  polysaccharides   §   Open  chain  or  ring  structure   §   Backbone  of  nucleic  acids  (RNA  and  DNA)   Fatty  Acids   §   Monomeric  constituents  of  lipids   §   Hydrophilic  and  hydrophobic  ends   §   Basic  structure:  CH -­‐CH3-­‐CH 2H =COO2  2   Nucleotides   §   Monomeric  constituents  of  nucleic  acids   §   DNA:  2-­‐deoxyribonucleic  acid     §   Lacks  oxygen  at  2’  carbon  (H  at  2’  carbon)   §   RNA:  ribonucleic  acid   §   Has  oxygen  at  2’  carbon  (OH  at  2’  carbon)   §   Each  nucleotide  composed  of  3  separate  units   §   5-­‐carbon  sugar  (ribose  or  deoxyribose)   §   Nitrogenous  base   §   Either  one-­‐ring  structure  (pyrimidine  base)  or  two-­‐ring  structure   (purine  base)   §   Molecule  of  phosphate  (PO )   2 §   RNA  vs.  DNA   §   RNA  is  single-­‐stranded   §   RNA:  5-­‐carbon  sugar  is  called  ribose  sugar  (has  oxygen)   §   DNA:  5-­‐carbon  sugar  is  called  deoxyribose  sugar  (lacks  oxygen)   §   Nitrogenous  bases  in  RNA  include  uracil  and  in  DNA  include  thymine   §   3  types  of  RNA   §   mRNA  (messenger)   §   tRNA  (transfer)   §   rRNA  (ribosomal)   §   Single  stranded  nucleic  acid  –  3  things  to  remember   §   At  5’  end,  the  phosphate  group  is  exposed   §   Phosphate  group  is  attached  to  5  carbon   §   At  3’  end,  the  OH  or  H  is  exprded   §   OH  or  H  is  attached  to  3  carbon   §   Location  of  nitrogenous  bases   §   Is  either  a  one-­‐ring  structure  (pyrimidine)  or  two-­‐ring  structure  (purine)   Amino  Acids   §   Monomeric  constituents  of  protein   §   All  amino  acids  have  a  COOH  (carboxylic  acid)  and  NH (amin2   group   §   Amino  acids  differ  only  in  the  nature  of  the  side  group  –  represented  by  “R”   o   20  different  amino  acids   §   Centrally  located  carbon   §   H  molecule   §   Many  amino  acids  can  be  linked  by  a  peptide  bond  –  this  forms  a  polypeptide   o   This  linkage  forms  a  protein   o   When  amino  acids  link,  amino  group  of  one  attaches  to  carboxylic  acid  group  of   the  other   o   One  H  from  amino  group  and  OH  from  carboxylic  acid  group  are  cast  off  à  H O 2  o   Since  water  is  cast  off,  this  process  is  called  dehydration  synthesis     Proteins  occur  in  4  levels  of  organization   o   Primary  –  straight  line  –  not  functional   o   Secondary  –  twisted  –  not  functional   o   Tertiary  –  twisted  to  the  point  that  molecule  becomes  globular  –  functional     o   Quaternary  –  even  more  twister  –  functional       Denaturation     o   When  heat  is  added  to  a  protein,  bonds  are  broken  and  the  protein  regresses  to  a  linear   (primary)  appearance   o   Once  cooled,  will  probably  not  return  to  original  form     Enzymes   •   Type  of  protein  that  lowers  the  energy  required  for  a  reaction   •   Biological  catalysts  –  do  not  change  themselves  when  active   •   Crucial  in  function  of  drugs  to  cure  diseases   •   Many  drugs  are  enzyme  inhibitors   o   Most  antibiotics  function  through  enzyme  inhibitors   •   Indicated  by  a  name  ending  in  “-­‐ase”   o   e.g.  DNA  polymerase   •   Many  require  a  cofactor  in  order  to  function   o   Cofactor-­‐  non-­‐protein  component   §   e.g.  iron,  zinc,  vitamin  B12   •   Enzyme  function   o   Enzyme  has  active  site  into  which  a  substrate  (any  material  onto  which  an   enzyme  acts)  can  fit   o   Enzyme  and  substrate  fit  together,  forming  an  enzyme-­‐substrate  complex   o   The  substrate  separates  from  the  enzyme  as  a  changed  substance  –  i.e.  the   product   o   Enzyme  is  not  changed  and  is  ready  to  begin  the  process  again   •   Remember:  enzymes  are  protein,  and  the  active  site  is  a  very  small  part  of  the  protein     Inhibition  of  enzyme  activity   •   Competitive  inhibition  (active  site)   o   Inhibitor  can  fit  into  the  active  site  rather  than  the  substrate,  so  different  product  is   produced   o   Ex:  sulfa  drugs   •   Non-­‐competitive  (allosteric)  inhibition   o   Inhibitor  doesn’t  fit  into  the  active  site,  but  blocks  it  so  that  no  product  is  produced     o   Ex:  cyanide     These  are  effective  ways  to  control  bacterial  and  viral  growth   •   Look  for  enzymes  to  selectively  inhibit   •   Cancer  growth  is  problematic  because  it  lacks  unique  enzymes   •   Viral  growth  is  difficult  to  control  because  they  redirect  the  inhibitor  and  use  it  to  create   more  of  the  virus     Biochemical  pathways   Definition:  a  sequence  of  enzymatically  catalyzed  chemical  reactions     Cell  (microbial)  metabolism   •   Catabolic  reactions  –  produce  energy  in  form  of  ATP   o   Breakdown  of  materials   •   Anabolic  reactions  –  use  energy  to  synthesize  products     Catabolism  –  primarily  sugars   o   Occurs  in  both  eukaryotes  and  prokaryotes   o   3  general  stages   1.   Glycolysis  –  process  of  breakdown  of  sugars  to  pyruvate   •   “lysis”  =  breaking  down   2.   Krebs  cycle  –  main  products  are  NADH  and  FADH   2 3.   Electron  transport  chain   o   Production  of  NADH  and  FADH results  in 2  nsport  of  oxygen  to  electron  transport   chain   o   Therefore,  Krebs  cycle  can’t  occur  in  absence  of  oxygen     Energy  production     •   Transfer  of  energy  from  nutrients  is  by  removal  of  electrons     •   This  usually  involves  the  removal  of  hydrogen   •   This  is  called  dehydrogenation   •   The  major  carriers  of  H  are:   •   Nicotinamide  adenine  dinucleotide  (NAD)   •   Flavin  adenine  dinucleotide  (FAD)   ***need  to  know  full  names  for  test***   •   The  energy  carried  by  these  molecules  is  used  to  make  ATP  from  ADP  in  the  electron   transport  chain     o   ETC  is  located  in  the  membranes  of  the  mitochondria   §   Since  bacteria  have  no  mitochondria,  ETC  is  located  in  plasma  membrane   •   Damage  to  the  plasma  membrane  inhibits  ATP  production   §   Most  ATP  is  produced  in  the  ETC   •   There  are  many  different  proteins,  polysaccharides,  and  lipids   o   All  are  degraded  through  activity  of  a  few  common  metabolic  pathways   o   Most  microorganisms  remove  electrons  from  carbs  (polysaccharides)  as  primary   source  of  energy   §   Glucose  –  most  common  carb  source   §   Adding  sugar  to  a  wound  gives  bacteria  a  preferred  energy  source  over   body  tissue   o   Proteins  and  lipids  will  suffice  in  absence  of  polysaccharides   o   Lipid  catabolism:  Beta  oxidation   §   Body  uses  oxidation  when  there  are  no  carbs   o   Proteins  broken  into  amino  acids  in  order  to  pass  through  cell  membrane   §   Body  digests  its  own  tissue  when  there  are  no  carbs  or  lipids             General  principles  of  respiration   Aerobic  and  anaerobic  respiration  are  similar  in  principle   Fermentation  is  fundamentally  different  from  those  processes     Aerobic  respiration   •   Definition:  uses  oxygen  as  the  terminal  electron  acceptor  in  a  membrane-­‐bound   pathway  for  ATP  generation   •   Most  prokaryotes  and  all  eukaryotes   •   Requires  external  terminal  electron  acceptor   o   Oxygen  enters  from  outside  the  body   •   Catabolism  –  breaking  down   •   Basic  steps:  Glycolysis  à  Krebs  cycle  à  electron  transport  chain   o   Product:  ATP   •   Electrons  are  in  the  form  of  hydrogen   •   At  the  end  of  electron  transport  chain,  H  must  bond  to  something   o   Oxygen  is  waiting  at  the  end  of  ETC  to  accept  H   o   Hydrogen  and  oxygen  bind  to  produce  H2O     Anaerobic  respiration   •   Uses  compounds  other  than  oxygen  as  the  terminal  electron  acceptor  in  a  membrane-­‐ bound  pathway  for  ATP  generation   o   Ex:  nitrates,  sulfates   •   Yields  less  ATP  than  aerobic  because  anaerobic  respiration  does  not  include  Krebs  cycle   o   Anaerobic  bacteria  don’t  grow  as  quickly   •   Anaerobic  bacteria  are  problematic  for  deep  wound  infections   •   Periodontal  disease   o   Gingival  pockets  between  teeth  start  to  erode  (receding  gums)  –  especially  in  the   elderly   o   Bacteria  accumulate  with  poor  dental  hygiene     o   Inflamed  gingiva  –  gingivitis   o   Solution:  cut  back  gums     Fermentation   •   Catabolism  of  substrates  by  mechanism  other  than  respiration  –  not  all  cells  can  do  it   •   Bacteria  and  yeast  yield  ethyl  alcohol  (EtOH)   o   Many  other  important  substances  are  produced,  especially  acids   •   Typical  fermentation  reaction   o   Only  small  amount  of  ATP  produced  –  is  all  produced  during  glycolysis   o   Polysaccharides  à  Monosaccharides  à  Pyruvate   §   These  three  steps  comprise  glycolysis   §   Pyruvate  breaks  down  in  one  of  two  ways:   •   Pyruvate  à  lactic  acid  and  other  acids   o   e.g.  yogurt,  sauerkraut,  pickles   o   Inhibit  growth  of  pathogenic  bacteria  (i.e.  spoilage)   o   Yogurt  contains  acidophilus   •   Pyruvate  à  acetaldehyde  à  ethanol   o   Commercially  important,  e.g.  citric  acid,  acetone   •   Doesn’t  require  oxygen  so  all  fermentation  pathways  are  anaerobic   o   Oxygen  may  be  present  but  not  used   •   Remember:  in  fermentation,  ATP  produced  only  in  glycolysis   •   Fermentation  begins  with  glycolysis  and  ends  with  formation  of  end  products   o   EtOH  is  only  one  possible  product  -­‐  other  possibilities  include  lactic  acid,  acetic   acid   o   Contain  stored  energy  –  not  completely  broken  down   o   Does  not  require  external  electron  receptor   o   Organic  substrate  acts  as  electron  donor  and  product  of  that  substrate  acts  as   electron  acceptor     Enzymes  affect  respiration  and  fermentation   •   Things  that  affect  enzyme  activity   o   Temperature   §   98.6F  (37C)  –  optimal  temperature  for  enzyme  function  in  human  body   §   Most  pathogenic  bacteria  also  do  best  with  98.6F     §   Fever:  body  trying  to  fight  sickness  –  might  inhibit  pathogenic  enzyme   activity   o   Substrate  concentration   o   pH       Microbial  growth  and  control     •   Microbial  growth  means  increase  in  number,  not  size   •   Most  antibiotics  are  directed  at  inhibiting  DNA,  RNA,  and  protein  synthesis   •   Binary  fission  is  a  type  of  asexual  reproduction   •   E.  coli  divide  every  20-­‐30  minutes  under  optimum  conditions   o   Enormous  growth  potential  –  in  10  hr,  1  cell  à  1  million  cells     Bacterial  growth   •   Bacteria  have  enormous  growth  potential     •   Introduce  bacteria  to  new  environment  à  go  through  growth  curve     o   Lag  à  exponential  growth  (log)à  stationary  à  decline  (death)   •   Lag  –  new  environment,  DNA  and  RNA  synthesis,  but  little  or  no  cell  division   •   Log  or  exponential  –  maximum  cell  multiplication   o   Each  increment  on  Y  axis  represents  10x  multiplication  of  previous  value   o   Most  sensitive  to  antibiotics  at  this  time  –  inhibits  DNA/RNA/cell  wall/protein   synthesis   §   Esp.  Penicillin   o   Maintained  for  relatively  short  time  –  use  up  space,  resources  –  self-­‐limiting   •   Stationary  à  death   o   Toxin  production  is  greatest,  nutrients  at  lowest  level   •   Death  –  more  cells  dying  than  multiplying     Effect  of  environmental  factors  on  growth  –  4  main  factors   §   Temperature   o   37C  (normal  body  temp)  –  pathogens  grow  best  at  this  temp   o   High  fever  –  not  optimal  growth   o   Freezing  inhibits  growth  but  doesn’t  kill  bacteria   o   Some  bacteria  grow  at  boiling  temps   o   Listeria  monocytogenes:  important  human  pathogen  that  grows  at  refrigerator   temps     §   Psychrophiles  –  bacteria  that  grows  best  below  15C   •   Mesophiles  –  most  pathogens  –  up  to  39C   •   Thermophiles  –  at  about  60C   o   Water  heaters,  hot  springs,  etc.     •   Hyperthermophiles  –  100C   o   Survive  due  to  amino  acid  substitutions  in  enzymes     o   Proteins  not  denatured  by  heat   Eukaryotic  cells:  highest  survival  temp  is  some  amoebae  at  60C     •   pH   o   Most  bacteria:  6.5  -­‐  7.5   o   Most  environments:  5  –  9   o   Fungi  are  acid  tolerant,  ex:  fruit  (fungi  are  eukaryotes)   o   Few  bacteria  grow  below  pH  of  4   §   Ex:  gastric  fluids,  vinegar   §   Exception:  Helicobacter  pylori  –  causes  ulcers  in  stomach  at  pH  of  1-­‐2   •   Relatively  new  discovery  –  ulcers  now  treated  with  antibiotics   instead  of  antacids   •   Carried  by  cats  –  zoonotic  bacteria?   •   Found  in  wells   o   Water  availability     •   Hypertonic  vs.  hypotonic  environment   •   Refers  to  amount  of  dissolved  salt  in  environment  vs.  in  bacteria   •   Water  always  wants  to  reach  equilibrium   •   Hypertonic:  higher  concentration  of  salt  outside  of  bacteria   §   If  any  bacteria  are  present,  water  will  flow  out  of  it  –  bacteria  dies   •   Surface  of  skin:  high  concentration  of  salt,  especially  with  sweat   •   Staphylococcus  aureus  –  grows  in  hypertonic  environments   §   Causes  MRSA  (skin  infection)   •   Oxygen  requirements   o   Obligate  aerobes  –  need  oxygen  to  multiply   o   Obligate  anaerobes  –  only  multiply  without  oxygen   o   Facultative  anaerobes  –  can  multiply  without  oxygen,  but  will  use  it  if  present   §   Ex:  E.  coli     Sending  electrical  current  through  bacteria  may  destroy  capsule/slime   •   Continuing  research     •   This  will  affect  sterilization  of  I.V.  catheters  and  heart  valves     Culture  media     Chemically  defined  media   •   Exact  chemical  composition  is  known   •   Very  difficult  to  make  –  not  typically  used  in  undergrad  lab  courses   Complex  media   •   Varies  from  batch  to  batch  and  contains  complex  additives   •   e.g.  serum,  blood,  milk,  meat  byproducts   o   skim  milk  agar   •   Agar  plates   o   Made  from  seaweed   •   TSA  –  trypticase  soy  agar  –  commonly  used  agar   •   Blood  agar  –  most  commonly  used  medium  in  hospital   o   Sheep  blood   •   Chocolate  agar  –  not  really  chocolate   o   Blood  turns  brown  when  cooked                                              


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