● Naming species: it can be difficult
○ Issues with language, personal biases, and different naming conventions affect the naming process
○ So there needs to be a universal naming system for naming organisms ○ Carolus Linnaeus:proposed that Latin should be the common language for naming (wrote Systema Naturae)
■ Said each organism gets two names “binomial nomenclature” ● Genus, species (ex. Homo Sapiens)
■ Came up with the system of hierarchical nomenclature
● Kingdom, Phylum, Class, Order, Family, Genus, Species We also discuss several other topics like What are the four steps of the cross bridge cycle?
■ (1977) Carl Woese: added Domain to the system of hierarchical
● Domain: Bacteria, Archaea, Eukarya
■ Because this system had difficulties with displaying evolutionary
relationships, it led to Phylogenetics
● Phylogenetics: a field that uses techniques and tools for reconstructing evolutionary relationships based upon evidence of common ancestry
○ Common ancestry is observed by fossils sharing the same characteristics (ex. hair on mammals)
■ Also by using genetic comparisons If you want to learn more check out What does falsework mean?
○ Phylogenetics is a tool used in systematics
● Systematics: method or approach for classifying and naming organisms in an evolutionary framework
● Cladograms(phylogenetic trees): shows relationships between organisms ○ The base of the tree is the common ancestor, with branches that show different characteristics (everything below it lacks that characteristic, everything above it possesses that characteristic)
■ ex. Lamprey, Shark, Salamander, Lizard, Tiger, Gorilla, Human
■ ex. Carl Woese’s Domains: common ancestor (base), Bacteria, Archaea, Eukarya
● Bacteria and Archaea: prokaryotes (on the branch)
● Eukarya: membranebound nucleus (on the branch)
● Carl Woese found that bacteria and archaea differ in how they synthesize/make proteins ● Ch. 27
● Virsuses:infect every group of organisms on the planet We also discuss several other topics like What are the 2 types of analysis?
○ Morphology is used to classify viruses based on two characteristics ■ Some sort of genetic material (RNA vs. DNA)
■ The type of capsid:outer protein covering that encases the genetic material (all viruses have a capsid)
○ Also classified based upon genetic material (some where main genetic material is RNA, some where main genetic material is DNA)
■ RNA viruses are much more likely to mutate and change form
■ The genetic material carries instructions on how to hijack cells and how to produce new viruses
● Virus structure:
○ Tail: used for leverage to penetrate the cell wall
● Bacteriophages: viruses that only infect bacteria
○ Very complex “virions”
○ Virion: individual virus
○ Tail fibers and whiskers: affect host recognition (if they don’t recognize the cell type they won’t fasten on to it)
○ Lytic Cycle: phases bacteriophages go through to replicate
■ Attachment: where they penetrate the cell wall of the bacteria
● Then injects it’s genetic material into the cell We also discuss several other topics like What happens because of precarity?
■ Synthesis stage: once it’s inside the cell, the viral DNA takes over the cellular replication and protein synthesis machinery to make parts of a new virus
■ Assembly stage: all viral pieces come together, forming virions
■ Release: where individual virions rupture and break through the cell, and enter the environment to infect other bacteria
○ Lysogenic cycle: the host cell does not die (different from Lytic Cycle) inactive phase for the virus
■ Integration: the viral DNA becomes part of the bacterial DNA (leads to prophage)
■ Propagation: where it replicates with the host cell genome when the cell divides (can continue through many cycles until something breaks the cycle)
■ Cell stress: food availability, environmental change, toxins (antibiotic) ■ Induction: viral DNA exits the genome Don't forget about the age old question of What is the ancient roman republic?
If you want to learn more check out How do we learn gender roles?
● Then goes on to the Lytic Cycle