Defense  Against  Infec.ous  Disease  Part  2  

IB  Bio  12  

Assessment  Statements Obj.

6.3.1 Define  pathogen.   1

6.3.2 Explain  why  an.bio.cs  are  effec.ve  against  bacteria  but  not  viruses.   3

6.3.3   Outline  the  role  of  skin  and  mucous  membranes  in  defense  against  pathogens.   2

6.3.4 Outline  how  phagocy.c  leucocytes  ingest  pathogens  in  the  blood  and  body  .ssues.   2

6.3.5 Dis6nguish  between  an#bodies  and  an#gens.   2

6.3.6 Explain  an.body  produc.on.   3

6.3.7 Outline  the  effects  of  HIV  on  the  immune  system.   2

6.3.8 Discuss  the  cause,  transmission  and  social  implica.ons  of  AIDS.   3

Assessment  statements  from:  Online  IB  Biology  Subject  Guide Command  terms:  hQp://i-­‐biology.net/ibdpbio/command-­‐terms/

3  Main  Lines  of  Defense  

1)  Physical  barriers  –  Skin,  mucous  membranes  

2)  Non-­‐specific  immune  system  –  Phagocy.c  leukocytes  

3)  An6gen-­‐specific  immune  system  –  Lymphocytes  (e.g.  B-­‐cells,  T-­‐cells,  Killer  cells)  

An.bio.cs  are  ineffec.ve  against  viruses!  

h,p://www.youtube.com/watch?v=RedO6rLNQ2o

Over-­‐use  of  an.bio.cs  is  accelera.ng  the  evolu.on  of  more  harmful  bacteria.  We  are  running  out  of  an.bio.cs  that  work  and  are  selec.ng  for  diseases  such  as  MRSA.  

An.bio.cs  are  designed  to  disrupt  structures  or  metabolic  pathways  in  bacteria  and  fungi:  •  cell  walls  and  membranes  •  DNA  synthesis  (replica.on)  •  RNA  polymerase  •  Transla.on    

These  do  not  exist  or  are  very  different  in  viruses,  so  the  an.bio.c  will  have  no  effect.    

Bacterial  drug  resisance,  from  Wiley  Essen#al  Biochemistry.  Find  out  more  here:  hQp://www.wiley.com/college/praQ/0471393878/student/ac.vi.es/bacterial_drug_resistance/index.html

An.bio.cs  are  ineffec.ve  against  viruses!  

Chlamydia  trachoma#s  bacteria.  Are  you  ready  for  the  end  of  an.bio.cs?  Guardian:  hQp://gu.com/p/2jxgj

Analyse  the  graph  below.  Over  .me,  outline  what  has  happened  to:  •  The  number  of  new  approved  an.bio.cs  •  The  diversity  of  new  approved  an.bio.cs    Suggest  reasons  for  your  answers.  Use  the  graph  to  write  your  own  DBQ  prac.ce  ques.ons.    

The  scariest  graph  you’ll  ever  see.  Read  the  ar#cle  by  Maryn  McKenna:  hQp://www.wired.com/wiredscience/2011/02/not-­‐many-­‐an.bio.cs/