Unformatted text preview:

BSCI106 EXAM 2 REVIEW(Lec13): Phylogenetic reconstructions (use ppt; Chap 26; Mastering biology)- Know how to interpret and build a phylogenetic tree o Only endpoints are livingo Branches are groups of closely related organismso Branch points are speciation events, where the lineages divergeo Any point along a line represents a species that is ancestral to all species tothe right of that pointo The far left point on this figure represents a species that is an ancestor of every species shown on the treeo Time is shown along the X axis of a phylogenetic tree, with the most ancient time on the left- Phylogeny- evolutionary history of a species or group of related specieso Increases emphasis on unity- shared ancestorso Inferred from morphological and molecular data- Taxonomy- the ordered division and naming of organisms- Taxon- taxonomic unit at any level of hierarchy (domain to species)- Branch point - represents the divergence of two specieso Represents a species that is the ancestor of all species that fall on lines to the right- Sister taxa - groups that share an immediate common ancestor- Polytomy - branch from which more than two groups emerge;formed by a branch point - Basal taxon - diverges early in the history of a group andoriginates near the common ancestor of the group- What kind of information you can and cannot get from a phylogenetic tree.o CAN: Can see patterns of descent Can get assumptions about relationshipso CANNOT: Cannot see phenotypic similarities (don’t look similar but have a common ancestor) Cannot find out when a species evolved or how much change occurred (no assumptions about time/which evolved first) Shouldn’t be assumed that a taxon evolved from taxon next to it- Homologous character and building a treeo Phenotypic and genetic similarities due to common ancestors1BSCI106 EXAM 2 REVIEWo Homology- Phenotypic and genetic similarities due to shared ancestry Homologous characters are used to infer phylogeny and construct phylogenetic treeso Analogy- similarities due to convergent evolution- Cladistics- approach to systematics in which organisms are placed into groups called clades based primarily on common descent o ?? Principles and limitations- Monophyletic (Clade)- a group composed of a collection of organisms, including the most recent common ancestor of all those organisms and all the descendants of that most recent common ancestoro Clade- group of species that includes an ancestral species and all of its decedentso Derived similarities- single origin, close relationships, not including outgroup- Paraphyletic- (not a clade)- group composed of a collection of organisms, including the most recent common ancestor of all those organisms;o Does NOT include all the descendants of the most recent common ancestoro Primitive similarities- single origin, but no close relationships, can includeoutgroup- Polyphyletic- (not a clade)- group composed of a collection of organisms in whichthe most recent common ancestor of all the included organisms is not included o Usually not included because the common ancestor lacks the characteristics of the groupo Usually considered “unnatural” and are reclassifiedo Covergent similarity- independent origin, but no close relationships- Unequal rates of evolution o Denoted by a break in a tree ex: prokaryotes and plants Paraphyletic- ancestor and only some descendants- Ex: prokaryotes, protists, invertebrates, fish, reptiles Monophyletic- ancestor and all descendants2BSCI106 EXAM 2 REVIEW- Ex: archaea, plants, animals, tetrapods, mammals, birds- Phylogeny : includes two principle techniques for reconstructing phylogenyo Outgroup analysis - distinguishing derived from primitive similarity Primitive similarity- all share similarity, including the outgroupDerived similarity- only the in-group share similarity, not the outgroupo Parsimony  Recognizes convergent similarity The cladogram requiring the fewest evolutionary changes is usually preferred Requires the fewest base-change events (not necessarily true to have least amount of branching)(Lec14): Origins of life (use ppt; book; 59 and 507-510; rest for clarification)- What is life? What does it mean to be alive?o Life is the potential for evolution Information storage (genotype) Replication with variation Metabolism- variation makes a difference (phenotype)- How did life arise?o Macroevolution- pattern of evolution above species levelo Chemical, physical, and natural selection lead to origin of lifeo Stanley Miller’s organic synthesis example (reducing atmosphere)- What are the crucial steps to life? (Understand very well!, not memorize only)o 4 big steps to life  1. Formation of small organic compounds- ex: amino acids, nucleotides, sugars, etc.- Oparin and Haldane hypothesis o Early atmosphere had little oxygeno Early atmosphere was reducingo This favored reactions forming organic molecules Use lightening and UV radiation as energy Oceans were the solution of organic molecules- Miller and Urey experiment o Created a reducing atmosphere Chemical evolution occurs readily if simple 3BSCI106 EXAM 2 REVIEWmolecules with high free energy are exposedto a source of kinetic energyo Formed many organic compounds (amino acids)o Problem- early atmosphere probably not that favorable 2. Formation of complex polymers (macromolecules- proteins and nucleic acids)- Possible without cellular catalysts- Need to concentrate monomers- Need to catalyze reaction inorganically- Not difficult to do- Abiotic synthesis of RNA nucleotides 3. Formation of liposomes to protect complex polymers - Can spontaneously form- Can carry out cell-like processes (reproduce and metabolize)o Store energy across membrane o Take up and release “metabolites” 4. Formation of a system of self-replication- Information and means of replicating it- May have preceded association with liposomes- RNA was first genetic material; provides template for DNA, more stable and more accurate replication- RNA versus DNA as the fist self replication systemo Many believe that RNA was first b/c RNA has both information storage and catalytic properties RNA is free to take on all shapes because it is single stranded which allows it to become a biocatalyst- Cech discovery, experiment, and conclusionso 1989 Altman Cech received Nobel Prize for finding an enzyme (RNA not a protein!) that did


View Full Document

UMD PSYC 355 - EXAM 2 REVIEW

Documents in this Course
Exam 2

Exam 2

13 pages

Exam 1

Exam 1

17 pages

Exam 2

Exam 2

12 pages

Exam I

Exam I

22 pages

Exam 2

Exam 2

12 pages

Exam 2

Exam 2

5 pages

EXAM 1

EXAM 1

5 pages

Load more
Download EXAM 2 REVIEW
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view EXAM 2 REVIEW and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view EXAM 2 REVIEW 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?