1. Defense against infections disease
Ms. Fargo
With some slides courtesy of Stephen Taylor

2. Assessment Statements Obj.
6.3.1
Define pathogen. 1
6.3.2
Explain why antibiotics are effective 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 phagocytic leucocytes ingest pathogens in the blood and body tissues.
6.3.5
Distinguish between antibodies and antigens.
6.3.6
Explain antibody production.
6.3.7
Outline the effects of HIV on the immune system.
6.3.8
Discuss the cause, transmission and social implications of AIDS.

4. Prokaryotes (no real nucleus) Divide by binary fission
Bacteria
Prokaryotes (no real nucleus)
Divide by binary fission
Can cause:
Food poisoning (e.g. Salmonella)
Ear and eye infections
Cholera, diarrhea

5. Acellular (non-living?)
Viruses
Acellular (non-living?)
Need a ‘host’ cell to carry out functions of life, including reproduction
Can have DNA or RNA
Mutate, evolve and recombine quickly
Cause:
Flu, HIV/AIDS, smallpox, measles, common cold, herpes, ebola
The 1918 flu epidemic killed between 50 and 130 million people.

6. Eukaryotes, reproduce with spores Cause:
Fungi
Eukaryotes, reproduce with spores
Cause:
Athlete’s foot, mould, ringworm
Allergic reactions and respiratory problems
Image from:

7. Protozoa Simple parasites Cause: Malaria Leishmaniasis Toxoplasmosis
Leishmaniasis image from:

14. Bactericidal vs. Bacteriostatic
Bactericidal or fungicdal agents
Kill microbes
Bacteriostatic and fungistatic
Stop further growth
Don’t kill existing cells
It is thought that because the growth of the pathogen is stopped, the body’s immune system will be able to kill it.

15. Antibiotics Can be selectively toxic by targeting such features as the
Bacterial cell wall
70 S ribosomes
This is the size of prokaryotic ribosomes
Enzymes that are specific to bacteria.
In this way, the human eukaryotic cells are unaffected.

16. Antibiotics are ineffective against viruses!
Over-use of antibiotics is accelerating the evolution of more harmful bacteria. We are running out of antibiotics that work and are selecting for diseases such as MRSA.
Antibiotics are designed to disrupt structures or metabolic pathways in bacteria and fungi:
cell walls and membranes
DNA synthesis (replication)
RNA polymerase
Translation
These do not exist or are very different in viruses, so the antibiotic will have no effect.
Bacterial drug resisance, from Wiley Essential Biochemistry. Find out more here:

18. Antibiotics are ineffective against viruses!
Analyse the graph below. Over time, outline what has happened to:
The number of new approved antibiotics
The diversity of new approved antibiotics
Suggest reasons for your answers. Use the graph to write your own DBQ practice questions.
Chlamydia trachomatis bacteria. Are you ready for the end of antibiotics? Guardian:
The scariest graph you’ll ever see. Read the article by Maryn McKenna: