1. Classification + Diversity of Life

2. Unit Outline Classification (Chapter 17.1)
introduction
Linnaeus and binomial nomenclature
modern taxonomy
dichotomous keys
Diversity (Chapter 17.2 and 18)
Six Kingdoms of Life
Viruses
Bacteria

3. Introduction to Classification
classification - grouping of objects or information based on similarities
taxonomy - branch of biology that groups and names organisms based on their characteristics (science of classification)
Aristotle’s system - animal or plant
This system stayed in place until a more useful one was developed in the 1700s.

4. Carolus Linnaeus aka Karl von Linne
developed a system known as binomial nomenclature
consists of a Genus and species name
written in Latin
italicized or underlined
first name capitalized, second lower case
tells something about organism

5. Modern Taxonomy
combines Linnaeus’s system of classification due to similarities and combines it with evolutionary thought.
phylogeny - the evolutionary history of organisms
organisms are grouped based on “shared derived characteristics” and “most recent common ancestors”

6. Hierarchical Taxonomic System
began with Linnaeus and has been constantly modified since.

7. Complete Classification of Homo sapiens

8. Dichotomous Keys

9. What is a Virus? Infectious particle consisting of a genome
either single- or double-stranded
either RNA or DNA
inclosed in a capsid - protein that surrounds it.
Replicate using metabolic machinery of host cells: bacteria, plant, animal
Possibly evolved from plasmids or transposons

10. Structural components of viruses
Genome: genes are contained on a single linear or circular nucleic acid molecule
Capsid: protein shell, often large numbers of identical subunits (capsomeres)
rod-shaped (helical)
polyhedral
complex
Envelope: derived from membranes of hosts

11. What is a “phage”? Bacteriophage: complex viruses that attack bacteria
Host Range: proteins on the outside of virus only recognize a few specific receptors on host cell surfaces.

12. Three patterns of Genome Replication
DNA viruses
RNA viruses
retroviruses
reverse transcriptase

13. Viral Life Cycles
Lytic cycle
Lysogenic cycle

14. Defenses against Infection
restriction enzymes
barriers
antibodies
vaccines

15. Bacteria
short generation span aids their evolutionary adaptation to changing environments
circular bacterial chromosome found tightly packed in a region called the nucleoid.
100x the DNA of a virus
1/1000 of the DNA of a eukaryote
plasmids are also found in many strains
genetic recombination produces new strains

16. Binary Fission
replication of chromosome proceeds in two directions from the single point of origin prior to binary fission.
most bacteria in a colony are identical (clones)

17. Genetic Recombination: Bacteria
Transformation: (recall Griffith’s exp.)
bacteria take up naked DNA
Transduction: (recall Hershey and Chase)
phages transfer genes from one bacterium to another
generalized and specialized transduction
Conjugation and Plasmids
2 cells temporarily join by appendages called sex pili

18. Most Common Shapes cocci: spherical bacilli: rod-shaped
spirilli and spirochetes: helical

19. Bacterial Cell Wall Structure
contain peptidoglycan: matrix of sugars with polypeptide cross-links
gram-positive
gram-negative
capsule

20. Bacteria Adapt Rapidly
short generations
transduction, transformation, conjugation
antibiotic resistance
endospores

21. Four Metabolic Categories
photoautotrophs
chemoautotrophs
photoheterotrophs
chemoheterotrophs
saprobes
parasites
nitrogen fixing bacteria = Rhizobium
Relationship to oxygen

22. Ecological Impacts decomposers symbiosis: symbiont and host
mutualism
commensalism
parasitism
Research and Technology

23. Disease and Bacteria opportunistic pathogens Koch’s postulates
Bacterial Pathogens
exotoxins
endotoxins

24. Classification Quiz What is taxonomy? Who is the father of taxonomy?
What is binomial nomenclature?
List the 7 taxa (levels) in order from most to least inclusive (biggest to smallest).
Write a scientific name using the correct rules we learned in class.

25. Quiz-cont’d.
Finish this sentence: A dichotomous key is used to _________________________.
See Dichotomous Key…
See Cladogram …