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Bio 111 Exam 2 Notes

by: Mallori Wisuri

Bio 111 Exam 2 Notes Biology 111

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Notes for chapters being tested in Exam 2!
Dr. Metzler
Class Notes
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This 17 page Class Notes was uploaded by Mallori Wisuri on Thursday February 18, 2016. The Class Notes belongs to Biology 111 at Ball State University taught by Dr. Metzler in Winter 2016. Since its upload, it has received 35 views.


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Date Created: 02/18/16
Bio  111  Exam  2     Ch.  6  Notes   2/02/16     • Organization  of  the  Cell   -­‐Microscopy  (online  video)   -­‐Experimental  Techniques  (online  video)   -­‐Structures       • Cell  Theory:     1. Cells  are  the  smallest  living  unit  of  organization   2. All  cells  come  from  other  cells  through  process  of  cell  division       LC:  All  cells  have  a  plasma  membrane?   TRUE;  if  you  are  a  cell  plasma  membrane  separates  you  from  everything  around   you.  All  plant,  prokaryotes  and  eukaryotes  have  a  plasma  membrane.       • Shared  Features  of  Cells   o Plasma  Membrane   o Chromosomes:  genetic  material   -­‐Prokaryotes  (circle)     -­‐Eukaryotes  (linear)   o Ribosomes:  make  proteins   o Cytosol:  goo  gel  component  in  the  cell   o Small:  size     o Dynamic       • Two  types  of  cells   Eukaryotes:   -­‐Animal  cell:  blob  like  structure  because  lack  of  cell  wall,  will  have  vacuole   but  will  not  have  a  central  vacuole.       -­‐Plant  cell:  have  cell  wall  give  them  a  defined  structure,  chloroplast  (green)   which  perform  photosynthesis  and  central  vacuole  which  takes  up  90%  of   the  cell,  plants  have  mitochondria.         • Function  Relates  to  Size  and  Shape   -­‐Specific  structure  that  relates  directly  to  the  function  it  performs     -­‐Examples:   Neuron:  long  connections  with  other  cells   Macrophage:  extensions  to  grab  bad  guys  that  will  make  you  sick.                   LC:  Proteins  are  bigger  then  cells?   FALSE;  Proteins  are  much  smaller  then  cells  and  animal  cells  are  built  of  lots  of   proteins.       • Surface  Area  to  Volume   -­‐Allows  them  to  have  maximum  ability  to  exchange  material     -­‐Bring  in  nutrients  and  expel  waste  material     -­‐If  cell  gets  too  big  it  won’t  be  able  to  exchange  material  fast  enough            to   survive   -­‐Why  cells  stay  small  on  purpose     -­‐Cells  work  hard  to  maximize  surface  area  and  is  why  they  don’t  have  a  smooth   surface  because  this  limits  surface  area.                    -­‐Example:     Small  intestines     Tissue  layer  goes  up  and  down  in  structures  called  villi.  Then  look  at  1   individual  cell  have  microvilli.  This  allows  for  maximum  nutrient  absorbance   when  food  passes  by  it.       • Prokaryotes   -­‐Smaller  than  eukaryotes  (harder  to  find  on  microscopes)   -­‐No  membrane  bound  organelles     -­‐Have  a  cell  wall  structure;  single-­‐celled     -­‐Ribosomes  are  smaller  in  size  compared  to  eukaryotes     -­‐Genetic  material  located  in  nucleoid       • Eukaryotes   -­‐Larger  in  size  than  prokaryotes   -­‐Contain  membrane  bound  organelles   -­‐Highly  organized;  put  everything  into  compartments  (organelles)   -­‐Larger  ribosomes  compared  to  prokaryotes       • Organelles!   o Nucleus     -­‐Most  prominent  organelles   -­‐Near  the  center  of  the  cell     Plant  cell  the  nucleus  is  shoved  to  side     Animal  cell  in  middle   -­‐Control  center  of  cell  structure  that  houses  DNA   -­‐DNA  controls  activity  that  goes  on  inside  of  the  cell   -­‐Double  membrane:  layer  1  and  2;  called  the  Nuclear  envelope   -­‐Nuclear  pores  are  studded  on  the  nuclear  envelope.  Pores  made  up  of   proteins  to  allow  pore  to  open  and  close   -­‐Regulation  of  what  goes  in  and  out     -­‐Nucleolus:  darker  staining  region  in  nucleus;  ribosomes  are  created   and  no  envelope  surround  it   -­‐Chromatin:  form  of  DNA  +  proteins  called  histones  that  help   condense  DNA  (bowl  of  spaghetti)     -­‐Nuclear  lamina:  located  directly  underneath  nuclear  envelope  (Put   rebar  in  concert);  it’s  a  support  structure  that  creates  the  circle  that  is   the  nucleus  (On  DNA  side).     -­‐Example:     Scientist  who  try  to  clone  things  and  remove  nucleus  from  a  cell  and   put  it  in  another  cell.  Shock  the  cell  then  cell  starts  to  divide  and  end   up  with  a  clone.       o Ribosomes   -­‐Don’t  have  a  membrane  and  is  why  they  are  found  in  prokaryotes       -­‐Job  is  to  make  proteins       -­‐Composed  of  2  subunit  (large  and  small)       -­‐Made  up  of  RNA  molecules       -­‐2  varities:   1.  Bound  ribosomes:  attach  to  the  Endoplasmic  Reticulum.   Make  proteins  that  are  going  to  leave  the  cell  or  sit  in   membrane  somewhere.   2.  Free  ribosomes:  floating  around  cytosol  of  cell.  Make   proteins  that  are  going  to  be  floating  around  in  cytosol.       -­‐Ex.  Tadpoles         2/04/16     LC:  Advantage  of  light  microscopy  over  electron  microscopy.     Light  microscope  can  watch  dynamic  movement,  which  you  can’t  in  electron   microscope  because  that  organism/cell  is  dead.       LC:  Image  shown  was  with  what  type  of  microscopy  (pollen  grain).   SEM  because  its  3D  and  looking  out  the  outside  (surface).       LC:  In  microscopy  staining  improves  what?     LC:  What  would  be  the  outcome  f  the  nucleolus  was  disrupted  and  no  ribosomes     Protein  mediated       LC:  What  would  happen  is  lysosomes  wouldn’t  function?       LC:  Why  do  plants  wilt?   Central  vacuole  emptied  out  because  you  did  not  water  the  plant.         o Endomembrane  System     -­‐Has  ability  to  move  proteins  to  the  interior  of  cell  or  to  be  secreted   from  the  cell.     -­‐Play  a  role  in  metabolism  to  synthesis  lipid  and  move  lipids  around.     -­‐Parts  can  help  detoxify  substances                COMPONENTS  INCLUDE  of  Endomembrane  System:   • Nuclear  envelope   • Endoplasmic  Reticulum:  All  membranes  of  ER  are  connected  to  one  another.   Variation(percentages)  in  quantity  of  ER  present;  all  cells  will  have  both   types.     2  types:     -­‐Rough  ER:  bumpy  because  studded  with  bound  ribosomes  on   its  surface.  Flattened  out.  Involved  in  protein  production.  Make   glycoproteins  which  is  a  protein  with  carbohydrate  added  to  it.       -­‐Smooth  ER:  no  ribosomes  on  its  surface.  Tubular  in   appearance.  Importance  in  synthesis  of  lipids,  help  to  detoxify  drugs,   storage  in  calcium  ions  (muscle  contraction).     Ex.  Ovaries/Testis,  Liver,  skeletal  muscle  cells       o Importance  of  the  ER   -­‐Clumping/Tangling  of  proteins  leading  to  diseases  such  as   Alzheimers.  Brain  of  individual  with  this  disease  will  slowly  shrink.       • Golgi:  reads  the  tags  on  proteins  and  determines  where  they  are  suppose  to   go  in  the  cell.     -­‐Made  up  of  flattened  membranes(cisternae)  that  are  not  connected  to  each   other.     -­‐Specific  sides   Cis  side:  receives  proteins  from  the  ER.  Proteins  come  in  vesicles  that   fuse  with  golgi  membrane  stack.     Medial  side:  middle   Trans  side:  faces  out  toward  plasma  membrane  and  where  proteins   exit  the  Golgi.  Proteins  exit  in  vesicles.     -­‐Haley-­‐Haley  disease:  cause  skin  irritation  disease  is  related  to  a  golgi  defect.       • Lysosomes:  Garbage  disposal  of  your  cell.  Can  destroy  any  biomolecule!     -­‐Membrane  sac  spherical  in  shape   -­‐Over  40  different  enzymes  inside  lysosome     -­‐It’s  job  is  to  break  things  down   -­‐pH  inside  of  lysosome  is  slightly  acidic(pH  5).  Enzymes  in  lysosomes  are   only  active  in  pH  of  5.  IMPORTANT  because  if  they  were  to  get  out  of   lysosome  they  would  be  able  to  destroy  everything  in/out  of  cell.  This  is  a   protective  mechanism!   -­‐40  different  genetic  disorders  related  to  lysosomes       o Phagocytosis:  cell  eating   -­‐How  a  lot  of  protist  get  their  food.     -­‐Food  vacuoles  fuse  with  lysosome  and  this  is  how  food  gets  broken   down.     o Autophagy:  self-­‐eating     -­‐Lysosomes  used  to  destroy  damaged  organelles       • Vacuoles:  membrane  bound  sac.     -­‐Several  different  types.     Plants  cells   1.  Central  vacuole:  storage  of  mostly  water,  but  also  can  store  pigments  or   wastes.  Watering  the  plant  generate  turgor  pressure  which  exerts  against  the   cell  was  and  is  why  plants  perks  up.     Animal  Cells     2.  Food  vacuole:  same  concept  in  phagocytosis   3.  Contractile  vacuole:  fills  up  with  water  then  contracts  and  squeezes  water   out  of  cell  in  protists.  This  helps  them  get  ride  of  that  extra  water  from  their   aquatic  environment  so  they  don’t  explode.  Helps  the  organism  maintain  its   osmotic  balance.         • Plasma  membrane       o Energy  Conversion     -­‐Aerobic  respiration:   Mitochondria:  location  for  aerobic  respiration  to  convert  energy  into   ATP.   *Have  a  double  membrane;  inner  membrane  folded  and  called   cristae.  Increase  SA  for  aerobic  respiration  to  take  place.     *Have  own  DNA;  dependent  on  DNA  in  nucleolus  still   *Reproduce  on  their  own   *Posses  their  own  ribosomes     -­‐Photosynthesis:   Chloroplast:  light  is  converted  into  chemical  energy,  which  is   converted  to  make  food.  Plants  make  all  food  and  oxygen.     *Have  a  double  membrane;  inner  membrane  folded  and  called   thylakoids.  Increase  SA  for  steps  of  photosynthesis.     *Have  own  DNA;  dependent  on  DNA  in  nucleolus  still   *Reproduce  on  their  own   *Posses  their  own  ribosomes     o Endosymbiosis  Theory     Mitochondria  and  chloroplast  came  from  prokaryotic  cells  that  eukaryotic   cell  engulfed  and  eventually  lost  their  function  to  be  on  their  own.         (JEOPARDY  GAME)­‐review-­‐ game.php?gamefile=1482820#.Vf9bzXt4hpl         Ch.  6  Video  Lecture  Notes   2/04/16     Microscopy     • Magnify:  making  the  image  bigger   • Resolution:  the  ability  of  micro  to  distinguish  between  two  separate  points.       • Light  Microscopes:  use  different  types  of  light  microscopes  to  manipulate  the   image  you  want.     1.  Brightfield:  are  scopes  where  you  are  just  shining  light   Want  to  see  cells  better  well  want  to  stain  the  cells  to  provide  contrast   to  see  the  shape  of  the  cell,  nucleus,  membrane  etc.  (Brightfield   stained  specimen)   2. Confocal:  light  microscopes  are  specific  wave  of  lights  that  can  excite   fluorescent  dyes  or  give  off  color.     -­‐Hooked  up  to  a  computer     3. Fluorescent:  stain  specimen  with  dye  so  when  you  hit  it  with  a  specific   wavelength  of  light  it  will  give  off  a  color.     -­‐Very  specifically  stain  individual  components  of  the  cell.       o Light  Microscopy:   -­‐Big  pro  lets  us  look  at  living  organisms;  you  can  see  them  moving,   functioning,  see  things  inside  of  them  moving.     -­‐Use  stains/dyes   -­‐Negative  is  that  detail  is  limited  because  most  microscopes  will  max   out  magnification  at  1000X.  Maximum  resolution  is  0.2microns.     -­‐Example:  amoebae       o Electron  Microscopy:  shooting  a  beam  of  electrons  at  specimen  not  a   beam  of  light   1. Scanning  Electron  Microscopy  (SEM)   -­‐Use  them  to  look  at  fine  surface  detail  of  organisms   -­‐Beams  bounce  off  surface  of  specimen     -­‐Kill  the  specimen  and  coat  it  with  thin  layer  of  golds   -­‐3D  image   -­‐Example:  amoebae  looks  differently  and  can  see  its  covered  with   cilia     2. Transmission  Electron  Microscopy  (TEM)   -­‐Use  them  to  look  at  the  very  fine  inside  detail  of  organisms   -­‐Beams  goes  through  the  specimen   -­‐Organism  are  cut  it  very  thin  sections  and  then  coated  heavy   metal  atoms     -­‐Kill  the  specimen     o Cell  Fractionation(animation  on  BB)   -­‐Technique  used  to  purify  organelles     -­‐Take  a  big  tube  of  cells  that  you  need  to  rupture  called   homogenization     -­‐Rupturing  cell  membrane  and  releasing  all  interior  contents  of  cell   -­‐Next,  you  put  the  tube  into  a  centrifuge     -­‐Different  parts  of  cell  have  different  densities  so  by  spinning   homogenized  cells  you  can  separate  out  different   components/fractions  of  the  cell  you  want  to  study       -­‐Pellet  and  supernatant     -­‐Used  for  experiments  to  study  function  of  specific  organelles       Ch.  6  Organization  of  the  Cell     2/09/16     LC:  Do  prokaryotes  perform  cellular  respiration?   Yes,  they  have  to  harvest  energy.  Use  cellular  membrane  to  perform  these  types  of   reactions.     LC:  Did  the  protein  go  through  entire  the  Entire  Membrane  system  based  off  the   radioactive  data?   -­‐No,  but  it  was  in  the  ER.  Started  in  the  ER,  and  then  went  to  the  Golgi,  last  place  it   went  to  the  cell  membrane.  Got  stuck  in  the  membrane  but  never  left  the  cell.     -­‐Proteins  in  the  membrane  don’t  work  properly  in  cystic  fibrosis  patients.         • Peroxisome:  look  very  similar  to  lysosome  or  small  vacuole.  It’s  a  little   membranous  sac  in  the  cytoplasm.     -­‐Doesn’t  have  ability  to  break  down  as  much  as  a  lysosome   -­‐Can  break  down  fatty  acids  and  hydrogen  peroxide.     -­‐Helps  to  get  rid  of  membrane  components  and  hydrogen  peroxide  generated   because  of  aerobic  respiration  pathway     -­‐Catalase  destroys  the  hydrogen  peroxide  (bubbling  when  put  hydrogen   peroxide  in  a  cut  on  skin)   -­‐Defective  enzyme  causes  X-­‐linked  adrenoleukodystrophy  (X-­‐ALD)   -­‐Glyoxysomes  special  versions  found  in  plant  cells.       LC:  Given  organelle  and  match  the  appropriate  function  of  the  cell.     -­‐Macrophage-­‐Lysosome   -­‐Algae  phtotoautotrophs–Chloroplast   -­‐Cardiac  muscles  need  energy-­‐Mitochondria   -­‐Plasma  cells  secrete  antibodies  (proteins)-­‐Rough  ER   -­‐Epididymis  secrete  glycoproteins-­‐Golgi       • Cytoskeleton:  3  components.  They  all  support  the  basic  structure  of  the  cell.     Very  dynamic  structures;  constantly  breakdown  and  build  them  back  up.     1. Microtubules:  movement  of  cell  and  components  inside  cell   -­‐Largest  component     -­‐Hollow  tube  (looks  like  straw)   -­‐Made  of  protein  called  tubulin     -­‐Have  a  plus  end  and  a  minus  end.  Both  ends  tubulin  can  come  on  and  off   (extend  or  shorten  microtubule).  Most  occurs  at  the  plus  end  while  the   minus  end  is  anchored  toward  the  center  of  the  cell.       -­‐Several  Roles:   *Pull  chromosomes  apart  during  mitosis  and  meiosis.  Spindle  fiber  is   built  from  microtubule.     *Serve  as  the  highway  of  your  cell.  Motor  proteins  drag  vesicles  along   microtubules     *Anchor  points  for  organelles.     *Major  component  of  cilia  and  flagella  to  allow  entire  cell  to  move   around         o Centrosome:  microtubule  organizing  center  in  animal  cells(MTOC)   -­‐Inside  are  two  centrioles  are  made  up  of  microtubules.  -­‐Oriented  at   right  angles  to  one  another.   -­‐Plants  do  not  have  these     o Cilia  and  Flagella:  extra  cellular  projections;  important  for  movement.   -­‐9+2  arrangement  of  microtubules.     -­‐Paris  of  microtubules:  9  around  the  outside  and  2  in  the  middle     -­‐Flagella:  acts  like  a  motor  and  spins  in  corkscrew  manner  to  propel   cell(looks  to  us  like  a  whip  like  motion)   -­‐Cilia:  function  like  ore  on  a  row  boat;  flip  back  and  forth.       o Role  of  Dynein   -­‐Motor  protein  help  to  carry  proteins  across  the  cell   -­‐Play  a  role  inside  the  cilia  and  flagella     Ex.  Dynein     -­‐Set  of  microtubules  connected  by  cross  linking  proteins,  cause  the   whole  thing  to  bend  (cilia  and  flagella  to  move).       LC:  Drug  effects  microtubules,  move  chromosomes  in  cell  divisions  of  cancer  cells.       2. Microfilaments:  movement  of  cell  and  components  inside  cell   -­‐Form  cleavage  furrow   -­‐Made  of  protein  called  actin   -­‐Strands  twisted  around  one  another  (2  chains  of  actin)   -­‐Found  right  underneath  plasma  membrane   Roles:   -­‐Muscle  contraction   -­‐Protist  use  microfilaments  to  help  them  move  around  via  amoeboid   movement  by  extending  components  of  cytoplasm.     -­‐Cytoplasmic  streaming  is  seen  in  plant  cells  where  they  actively  circulate   components  in  cytoplasm.         3.  Intermediate  filaments:  important  in  cell  structure.     -­‐No  role  in  movement     -­‐Give  strength  and  stability  in  cell   -­‐Not  dynamic  (You  don’t  build  up  them  up  or  break  down  them  down)   -­‐Made  of  many  different  types  of  proteins  (ex.  keratin)   -­‐Like  a  big  wire  cable  holding  up  a  suspension  bridge   -­‐ALS  is  related  to  defect  in  intermediate  filament.  Skin  has  no  strength  or   stability         • Extracellular  Components     o Cell  Wall   -­‐Most  prokaryotes  and  plant  cells  have  a  cell  wall   -­‐In  single  celled-­‐organisms  the  major  function  is  to  be  protective   -­‐In  plant  cells  the  cell  wall  is  important  structurally     o Extracellular  Matrix  (ECM):  animal  cells  build;  secrete  it  to  outside  of   the  cell.  4  main  components  make  this  up.     1. Collagen:  protein,  big  fibrous  protein  runs  parallel  to  surface  of  cell.   Provides  flexibility/stability.  They  fill  up  the  gaps  between  the  cells.     2. Proteoglycans:  protein  and  carbohydrate  combination.  Provide   collagen  something  to  embed  itself  in.     3. Fibronectin:  connects  collagen  fibers  to  surface  of  the  cell.   4. Integrins:  sitting  in  the  cell  membrane  they  are  the  anchor  point  for   fibronectin.  Important  in  cell  communication.         2/11/16   Ch.  6  continued       • Cell  Connections  (Intracellular  junctions-­‐4  types):  cells  means  of   communication  and  or  holding  the  cell  together.       o Communication  (2  types)     -­‐Plasmodesmata:  allow  for  small  molecules  and  ions  to  directly  pass   from  one  cell  to  another.  Cells  communication  in  a  rapid  manner.  Is  a   hole  in  the  cell  wall  directly  connected  between  2  plant  cells.     -­‐Gap  Junction:  allow  for  small  molecules  and  ions  to  directly  pass  from   one  cell  to  another.  Cells  communication  in  a  rapid  manner.  It  is  not  a   direct  connection  of  membrane.  It  is  produced  by  several  proteins   called  connexins  and  they  insert  them  selves  into  the  membrane.  They   can  open  and  close.     Ex.  Heart  cells  that  beat  together     o Connections  (2  types)  used  in  creating  tissue  layer;  only  found  in   animal  cells.     -­‐Desmosomes:  directly  connected  to  intermediate  filament.  Do  not   have  capability  to  seal  area  off.     Ex.  Skin  to  create  strong  flexible  tissue  layer     -­‐Tight  junctions:  hold  cells  together  so  tightly  they  have  ability  to   completely  seal  an  area  off;  no  molecules  can  pass.   Ex.  Blood  brain  barrier  and  small  intestine  in  epithelia  layer.       Ch.  7  Membranes  Characteristics  and  Transport       • Phospholipid  characteristics:   -­‐Amphopathic:  hydrophilic  and  hydrophobic  qualities   -­‐Form  a  lipid  bilayers  when  put  in  water;  this  is  the  backbone  of  membrane   -­‐Has  a  uniform  shape  overall     • Fluid  Mosaic  Model:     -­‐Membrane  has  fluid  characteristics;  everything  in  the  membrane  has  capability  to   move  around     -­‐Mosaic  because  it’s  made  up  of  more  then  one  thing.     -­‐In  membrane  have  proteins,  cholesterol,  carbohydrate  components.  Carbohydrate   always  added  to  the  protein  or  phospholipid.       • Characteristic  that  membrane  possess       o Fluidity:  cells  work  hard  to  maintain  optimal  fluidity.  Don’t  want   it  to  become  gel  or  move  around  too  much.     -­‐Phospholipids  perform  lateral  movement  (moving  right  to  left)  on   the  same  leaflet/side.   -­‐Phospholipid  perform  flip  flop  where  they  flip  from  one  side  to   the  other  side.  This  rarely  happens;  normally  when  a  cell  is  about   to  die.     -­‐This  movement  depends  on  the  type  of  lipids  that  are  present.   *Saturated(solid)  less  fluid  membrane  because  tails  interact   more  through  Van  Der  Waals.       *Unsaturated(liquid)  more  fluid  because  the  tails  kink.   -­‐Insert  more  cholesterol  molecules  in  the  membrane.  Serves  as  a   buffer  molecule.  Inserts  itself  in  between  fatty  acids  tails.     -­‐The  membrane  will  not  rupture  because  of  the  fluidity  capability   that  allows  the  membrane  to  fill  in  the  gaps  when  being  pulled,   poked,  etc.       LC:  Least  viscous  (most  fluid)  to  most  viscous  (most  solid).   Mostly  unsaturated(kink  tails)-­‐-­‐-­‐partial  amount  of  unsaturated  with  some   saturated-­‐-­‐-­‐-­‐-­‐all  saturated(no  kink  tails)       o Membrane  Proteins  (Mosaic)   Two  types  of  proteins:   1. Integral  proteins:  tightly  connected  to  the  membrane   -­‐Classified  as  a  transmembrane  because  it  spans  the  entire   membrane.     -­‐Inserted  into  the  membrane  and  to  get  the  protein  out  you  would   have  to  destroy  the  entire  membrane.     2. Peripheral  proteins:  it  has  a  lose  connection  to  cytoplasmic  side.     -­‐Don’t  have  to  destroy  membrane  to  free  those  proteins.       -­‐Carbohydrates  can  be  added  to  proteins  and  lipids  (glycoprotein  and   glycolipid)     LC:  What  amino  acid  would  most  likely  present  on  the  transmembrane  domain  of   integral  membrane  protein.     -­‐A  hydrophobic  amino  acid  like  valine.   -­‐What  part  of  membrane  is  transmembrane  siting  it,  its  sitting  in  the  hydrophobic   part.         o Membrane  Protein  Function:   1. Transport(FOCUS  ON)   2. Enzymatic  activity   3. Signal  transduction   4. Cell-­‐cell  recognition   5. Intercellular  joining   6. Attachment  to  cytoskeleton  and  extracellular  matrix       o Asymmetrical:  Extracellular  and  Intracellular  leaflets  look   different  from  one  another.  Because  they  contain  different   proteins.  Which  can  causes  different  sides  to  have  different   functions  because  of  the  proteins  presented  there.           o Selective  Permeability     -­‐Very  small  you  can  easily  pass  through  the  membrane   -­‐Lipid  soluble  and  handle  hydrophobic  core  of  the  membrane   -­‐Charged  you  will  need  assistance   -­‐Big  like  amino  acid,  small  sugars  you  will  need  assistance     LC:  Which  of  the  following  molecules  will  diffuse  most  quickly  across  a  lipid  bilayer   membrane?   -­‐Oxygen,  yes!   Charged  molecules  no   Glucose  is  a  big  sugar  molecule     Water  moves  into  cell  in  a  different  mechanism     o Diffusion   -­‐Does  not  require  a  membrane     -­‐No  net  energy  because  it  is  a  passive  process   -­‐Energy  comes  from  the  random  movement  of  molecule   -­‐Net  movement  down  a  concentration  gradient  (high   concentration  to  low  concentration)  Move  to  equilibrium   -­‐Vast  majority  move  down  but  some  high  because  of  that  random   movement   -­‐Concentration  of  1  molecule  does  not  effect  the  concentration  of   another  molecule     -­‐No  net  flow  means  they  are  not  moving  just  moving  at  equal   rates     2/16/16   Ch.  7  continued       o Osmosis:  movement  of  water  across  a  membrane.   -­‐Special  case  of  diffusion  movement  of  water  molecules   -­‐No  net  energy  because  it  is  a  passive  process   -­‐High  water  concentration  to  low  water  concentration     -­‐Important  in  animal  cells  because  if  these  cells  don’t  balance   water  in  and  out  of  the  cell  it  can  shrivel  up  or  explode.     -­‐Terms  need  to  know/understand.  These  terms  are  describing   solute  concentration!  You  are  paying  attention  to  the  water   movement.     *Isotonic:  equal  solute  concentration  between  cell  and  an   environment  is  balanced.  This  is  the  preferred  state  by  animal   cell,  but  not  plant  cell  because  it  draw  water  out  of  central   vacuole.  Water  moves  in  and  out  of  cell  at  an  equal  rate.     *Hypertonic:  high  solute  concentration;  therefore  water   concentration  is  low.  Water  is  going  to  leave  the  cell  and  the   cell  will  shrivel  up.     *Hypotonic:  low  solute  concentration;  therefore  water   concentration  is  high.  Water  is  going  to  enter  the  cell  and  the   cell  will  lyse/explode.  Plant  cells  prefer  this  situation  because   their  central  vacuole  will  be  at  maximum  and  turgor  pressure   will  form.       LC:     -­‐Cell  1:  in  a  hypotonic  environment  less  solute  outside  the  cell  so  water  will  go  into   the  cell.     -­‐Cell  2:  in  a  hypertonic  environment  more  solute  outside  the  cell  so  water  will  go  out   of  the  cell.       Group  Work(Real  life  osmosis  examples):   -­‐Netty  pot:  this  is  a  hypertonic  solution  to  your  cells.  It  draws  the  water  out  of  the   cells  and  your  nasal  passage  opens  up  and  you  can  breathe  again!   -­‐Contact  solution  in  tap  water:  this  is  a  hypotonic  solution.  Water  will  rush  into  the   cells  on  surface  of  lens(eye)  and  thus  rupturing  them.       o Osmoregulation:  single  celled  organisms  who  live  in  an  aquatic   (hypotonic)  environment.     -­‐Have  a  contractile  vacuole  to  maintain  osmotic  balance.  They   have  to  be  able  to  pump  water  out.     -­‐They  are  not  isotonic  to  their  environment.  Water  is  constantly   coming  across  their  membrane.       LC:  Marine  algae  cell  taken  from  saltwater  environment  and  put  into  a  freshwater   environment,  what  will  algae  cell  immediately  do?     -­‐Absorb  water  being  placed  into  a  hypotonic  environment  volume  of  cell  will   expand.       o Facilitated  Diffusion   -­‐Passive  process   -­‐Molecules  that  are  too  big,  charged,  can’t  deal  with  hydrophobic   portion  of  cell  membrane  will  use  this  process.     -­‐Diffusion  occurs  with  the  help  of  a  transport  protein.  This  protein  is     a  safe  tunnel  to  get  through  the  membrane.     -­‐2  varieties:   *Channel  Proteins   Ex.  Gated  ion  channel,  aquaporin   *Carrier  Proteins:  solute  being  transported  interacts  more  with   the  carrier  protein  and  a  shape  change  occurs.     Ex.  Glucose  transporters       o Active  transport   -­‐Molecules  are  being  moved  against  their  concentration  gradient,   which  is  moving  it  away  from  equilibrium.     -­‐Always  requires  the  use  of  a  transport  protein   -­‐Cellular  energy  needed  in  form  of  ATP;  break  ATP  molecule  down     -­‐Ex.  Sodium  Potassium  Pump:  brings  two  K  in  and  3  Na  out   Ion  pumps  create  membrane  potential.  Creating  BOTH  a  charge   and  concentration  gradient  difference.  Called  an   electrochemical  gradient!  Cell  uses  this  to  do  work.       o Cotransport:  cell  purposefully  sets  up  a  gradient   -­‐Active  transport     -­‐Coupling  active  transport  and  diffusion   -­‐Manipulate  he  situation  to  get  what  they  want       • How  do  we  move  big  stuff  (ALL  are  active  transport)   o Exocytosis:  way  to  remove  things  from  the  cell   -­‐Material  being  removed  is  placed  into  a  vesicle.  This  vesicle  moves   along  cytoskeleton  (microtubules)  and  once  it  gets  up  to  plasma   membrane  then  pits  its  contents  out.     -­‐This  does  not  cause  the  cell  to  get  bigger;  surface  area  to  volume   ratio.       o Endocytosis:  way  to  bring  things  into  the  cell.   -­‐3  different  ways!   *Phagocytosis:  cell  eating;  grab  insoluble  particles  like  food  or   bacteria.  Bring  it  inside  in  a  vacuole  type  structure  and   degrades  the  contents.     *Pinocytosis:  cellular  drinking;  bringing  dissolved  material   inside.  Important  in  the  small  intestines  and  how  we  absorb   nutrients.     *Receptor-­‐Mediated  Endocytosis:  involves  a  receptor/ligand   interaction.     -­‐Way  to  uptake  cholesterol  and  in  the  immune  system   -­‐Very  specific       Ch.  11  Cell  Communication   1/18/2016     • Purpose  of  cell  signaling  is  to  get  cells  or  organism  to  make  a  response.       • Types  of  signaling:   1.  Direct  contact:  cells  physically  touch  each  other.  These  are  cell  junction  like   gap  junctions(in  animal  cells)  and  plasmodesmata(in  plant  cells).       2.  Distance  :  a  few  specific  types.     *Local  signaling:  response  is  local.     -­‐Paracrine  signaling.  Have  a  cell  secrete  signaling  molecule  usually   protein  there  are  cells  close  by  and  that  signaling  molecule  tell  those  cells  to   do  something.   -­‐Synapse:  signal  between  neurons       *Long  distance:  gets  in  circulatory  system  and  the  response  could  be   organism  wide.     -­‐Endocrine  signaling:  hormones  get  into  the  circulatory  system  and   then  this  causes  an  effect  far  away  from  where  it  was  originally   generated.         • Stages  of  Cell  Signaling:     1. Reception:  when  cell  receives  the  signal  molecule.  This  involves  a  ligand   binding  to  a  receptor.  Receptors  can  be  located  on  the  surface  of  the  cell  or   inside  cell.     -­‐Ligand  and  receptors  are  both  proteins.   -­‐Interaction  between  ligand  and  receptor  are  very  specific  .  Most  receptors   will  only  bind  one  ligand.  This  allows  for  a  lot  of  control  of  this  process.     -­‐This  causes  a  shape  change  in  the  receptor.    This  shape  change  will  allow  the   receptor  to  be  activated  and  be  able  to  move  on  to  the  next  stage  in  cell   signaling.       2. Transduction:  transduce  the  signal,  series  of  molecules  that  passes  the  signal   along.  Moves  everything  toward  where  we  are  going  to  get  a  response.   -­‐2  most  frequent  ways:   *Phosphorylation  cascade:  keep  adding  a  phosphorylation  to  the  next   guy  in  line  or  in  the  chain.  Series  of  activation  events  and  they  activate   the  next  guy  and  continued  down  the  line.     -­‐Several  proteins  involved  in  the  process.  Their  names  will  always   involve  kinases!     -­‐Occur  frequently  with  tyrosine  kinase  receptors.     *Second  messengers:  1  messenger  is  ligand  (signal  molecule).  Most   common  second  messenger  is  cAMP.     -­‐Common  with  G  proteins.     -­‐cAMP  or  ions  t  levels  increase  and  activate  another  relay  molecule   -­‐Second  messenger  passageways  are  shorter.       3. Response:  cells  going  to  make  a  response.  The  signal  is  telling  the  cell  to  do   something.     -­‐2  types:   *Nuclear:  effector  molecule  goes  inside  the  nucleus  and  interact  with   DNA.  Effect  protein  synthesis  up  or  shut  it  down.   *Cytoplasmic:  protein  activity  is  affected.  Increase  or  decrease  its   activity.       • Type  of  Receptors:   1. G  protein-­‐coupled  receptors:  located  in  cell/plasma  membrane   -­‐Largest  group  found  in  cells     -­‐G  protein  interacts     -­‐Receptor  binds  to  the  ligand.  This  causes  a  shape  change,  which  then  allows   the  receptor  to  bind  to  the  G  protein.  The  G  protein  then  moves  in  the  plasma   membrane  and  moves  to  an  enzyme  in  the  membrane.  This  then  activates  the   enzyme  and  reception  is  completed.     -­‐Huge  in  sensory  cells/receptions                  2.  Tyrosine  Kinase  receptor:  found  in  the  plasma  membrane.     -­‐Important  in  the  growth  of  cells  and  immune  system     -­‐Heavy  target  for  cancer  cell  mutations   -­‐In  their  cytoplasmic  tails  there  are  several  amino  acids  (Tyrosine).  Kinase   comes  from  the  phosphorylation  which  means  to  add  a  phosphate  group.   -­‐Signal  molecule  bind  to  each  individual  receptor,  which  causes  receptors  to   form  a  dimer,  thus  activating  them.     -­‐Phosphorylated  each  other  tyrosine  once  activated.     -­‐Other  proteins  in  cytoplasm  that  will  interact  with  phosphorylated  tyrosine   and  then  the  signal  is  passed.       3.  Membrane  receptors-­‐Ion  Channel:  form  of  facilitated  diffusion  that  helps  to   send  a  signal.     -­‐Chanel  protein  that  also  functions  as  a  receptor.     -­‐Ligand  binds  to  receptors,  channel  protein  changes  shape  allowing  the   channel  to  open.     -­‐Ions  can  then  move  into  the  cells  and  thus  lead  to  cellular  response.     -­‐Ligands  release  and  channel  protein  closes.     LC:  Which  best  describes  a  cell-­‐signaling  pathway.     -­‐Binding  of  a  ligand  on  one  side  of  a  membrane  that  results  in  a  change  on  the  other   side.       Intracellular  receptors-­‐steroid  hormone:  lipid  like  molecules  and  can  come  across   the  membrane     -­‐Signal  can  be  passed  much  more  simply.     -­‐Receptor  protein  is  located  in  the  cytoplasm  or  nucleus.  The  ligand  molecules  come   across  the  cell  membrane  and  binds  to  the  receptor.  As  a  whole  unit  it  interacts  with   DNA  to  cause  a  response.     -­‐By  passes  the  transduction  step!     • Signal  Amplification:  means  to  increase  the  response  from  a  few  ligand   molecules.     -­‐Allows  the  cell  to  make  massive  response  even  though  it  only  binds  a  few   signal  molecules.     • Specificity:  cells  make  different  kind  of  receptors  and  signal  molecules.     -­‐Different  cells  act  different  transduction  pathways  based  on  proteins  they   possess   -­‐Receptor  is  the  same  but  what  happens  inside  the  cell  is  different.  There  are   different  relay  molecules.         -­‐Due  to  different  cells  expressing  different  genes.         • Apoptosis:  process  of  a  programmed  cell  death.     -­‐Cell  decides  there  is  so  much  wrong  with  it     -­‐For  infected,  damaged  or  old  cells.   -­‐Doesn’t  harm  other  cells  around  it.     -­‐Ex.  Sun  burned  skin  cells     -­‐Signal  for  apoptosis  can  come  from  outside  the  cell  or  the  own  cell  can  do   this  as  well.   -­‐Plays  a  role  when  developing  embryonically.  Ex.  Fingers/toes   -­‐Abnormal  signaling  of  cancer  cells.  They  turn  off  apoptosis  and  cell  can’t  kill   itself.    


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