1. Host Defense
Dicer
Animals Fig. 8.16
dsRNA
– immune system Dicer cleaves dsRNA
into shorter segments
– RNA interference siRNA
(RNAi)
RISC
• Dicer – dsRNA RISC complex
binds siRNA and
nuclease separates the
strands
• siRNA – short
RISC complex finds
interfering RNA mRNA complementary
to siRNA
• RISC – RNA-
mRNA
induced silencing
complex RISC cleaves mRNA
• Slicer – ssRNA
nuclease RNA fragments degraded by Slicer

3. Fig. 20-7a in the 11th edition

4. Chemical antimicrobial agents used to control
microorganisms that are harmful to humans:
Sterilants destroy all forms of microbial life
; Disinfectants kill microorganisms, but endospores
are typically resistant
Sanitizers reduce the microbial load but may
not eliminate all microorganisms
Antiseptics kill or inhibit growth of
& Germicides microorganisms on living tissue

5. 1888-1955 Alexander Fleming
1929 discovered antimicrobial effects of
penicillin G made by the fungus Penicillium
on Staphylococcus by chance
1945 Nobel Prize in Medicine -
Fleming, Howard Walter Florey and
Ernst Boris Chain

6. Vancomycin
• Glycopeptide antibiotic
• Binds to pentapeptide of the
peptidoglycan precursor
• Produced by a soil microbe
Amycolatopsis orientalis
• Effective against Gram-
positive Bacteria

7. Platensimycin
• Produced by Streptomyces platensis
• Inhibits fatty acid biosynthesis enzyme
Fig. 27.25

8. An example of an echinocandin

9. An example of a polyoxin

10. Bacterial cell with
chromosomal mutation Bacterial cell not
altering target of antibiotic resistant to antibiotic
resistant to antibiotic
Transformation
Transfer of free DNA
Lysis of cell
Previously
susceptible cell
is now resistant
to antibiotic

11. Bacterial cell with R plasmid Bacterial cell not
resistant to antibiotic resistant to antibiotic
Chromosomal DNA Conjugation
Copy and Transfer of R plasmid
Previously
susceptible cell
is now resistant
to antibiotic

12. Fig. 27.29 Candida albicans *
Key: Acinetobacter sp.
Gram-negative Enterococcus faecium*
Gram-positive
Streptococcus pneumoniae
Gram-positive/
acid-fast Mycobacterium tuberculosis*
Fungus
Haemophilus ducreyi
Salmonella typhi
Antimicrobial Haemophilus influenzae
drug resistance Neisseria gonorrhoeae
human pathogens Pseudomonas aeruginosa*
continue to Salmonella sp.
emerge. Shigella dysenteriae
Shigella sp.
Other gram-negative rods
Staphylococcus aureus*
1950 1960 1970 1980 1990 2000 2010
Year

13. Eon Billion Evolutionary Oxygen Metabolic and
Fig. 14.7 years ago event level other highlights
Comparable to
0 Extinction of the dinosaurs
Fig. 11.8 in the
Phanaerozoic Cambrian
11th edition
0.5 Early animals
Multicellular 20%
1.0 eukaryotes
Precambrian
10%
Proterozoic
1.5
First eukaryotes 1% Ozone shield
2.0
Great oxidation 0.1%
2.5 event
Cyanobacteria Oxygenic photosynthesis
3.0 (2H2O O2 + 4H)
Archaean
Purple and green Anoxygenic photosynthesis
3.5 bacteria (H2S S0 + 2H)
Anoxic
First cellular Methanogenesis
4.0 life (CO2 + 4H2 CH4 + 2H2O)
Hadean Formation of
crust and ocean
4.5 Formation of Earth

14. Fig. 11-9 in the
11th edition
(oxygenic)
(aerobic)

15. The Hydrogen Hypothesis – how the
first eukaryotic was formed?
Host cell -
Archaea
Symbiont cell -
dependent on
Bacteria
H2 for electron
producing H2;
source to make
lipid gene transfer;
energy
precursor of
Symbiont cell –
mitochondrion
photosynthetic
cyanobacterial-
like ancestor

17. Fig. 14.15
Fig. 14.14
Fan-shaped
Dichotomous
outgroup

18. Branches show order of descent and node ancestry.
Branch length reprepresents number of nucleotide changes
Fig. 14.14d
Internal nodes
denote common
ancestor
Nodes at the tips
denote species/strains

19. Fig. 11.20 in
11th edition

20. Fig. 11.21
in 11th
edition