Bio 311D Week Notes (2/17-2/22)
Bio 311D Week Notes (2/17-2/22) BIO 311D
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This 8 page Class Notes was uploaded by Liam Murphy on Monday February 22, 2016. The Class Notes belongs to BIO 311D at University of Texas at Austin taught by Dr. Mark Bierner in Winter 2016. Since its upload, it has received 318 views. For similar materials see Introductory Biology II in Biology at University of Texas at Austin.
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Date Created: 02/22/16
The History of Life on Earth; Phylogeny 2/17/22 ▯ Vocab: ▯ Phylogeny: the evolutionary history of a species/group of species ▯ Stromatolites: solid structure created by single-celled microbes called cyanobacteria (blue-green algae). The cyanobacteria form colonies and trap sediment with their sticky surface coatings. The trapped sediment reacts to calcium carbonate in the water to form limestone (fossilized record of early prokaryotes) ▯ Autotrophic prokaryotes: An organism capable of synthesizing its own food from inorganic substances, using light or chemical energy ▯ Serial endosymbiosis theory: the notion that complex living cells results from evolutionary processes in which earlier cells merge in a series of successive combinations to eventually form larger, more complex molecules ▯ ▯ Key concepts: Key events in life’s history include the origin of single-celled and multicelled organisms and the colonization of land Phylogenies show evolutionary relationships Phylogenies are inferred from morphological and molecular data The first single-celled organisms appeared on Earth approximately 3.5 billion years ago. About 3 billion years elapsed before the colonization of land occurred approximately 500 million years ago To construct phylogenies, biologists use systematics, a discipline focused on classifying organisms and determining their evolutionary relationships The study of fossils have helped geologists establish a geologic record of Earth’s history The first single-celled eukaryotic There is fossil evidence that cyanobacteria and other photosynthetic prokaryotes coated damp territorial surfaces well over a billion years ago. However, larger forms of life did not begin to colonize land until about 500 million years ago ▯ ▯ Questions: ▯ Tell me about the major evolutionary events depicted in this illustration (slide 14) Depicts earths begin and when each vital event occurred, ending with the production of humans o After the origin of earth, prokaryotes (bacteria and archea) A billion and a half years without eukaryotes o Eukaryotes: linear DNA organized into chromosomes and completed with proteins called histones Evolution is a long overall process ▯ What does the picture tell you about understanding evolutionary biology and understanding the concept of time in evolution? Everything is connected and related to one another ▯ What were the first single-celled organisms, and where does the earliest evidence of their origin come from? Prokaryotes, formed from earths volcanic existing conditions ▯ How long were prokaryotes the only life forms on Earth? Around 1 and a half billion years Prokaryotes were heterotrophs (molecules in oceans stay alive, metabolize, and get their energy) Needed photosynthetic prokaryotes to create oxygen ▯ What’s the relationship between the evolution of photosynthesis and the appearance of atmospheric oxygen? Photosynthesis: H2O + CO2 + sunlight CH20 + O2 No oxygen in water yet, so now oxygen gets in water. First oxygen combines with iron creates iron oxide, eventually oxygen building up in the water becomes more oxygen saturated, High to low concentration, oxygen gets to atmosphere and changes ▯ What are cyanobacteria and what was their role? ▯ What did the increase in atmospheric oxygen mean for the evolution of prokaryotic organisms? All prokaryotes are anaerobic and oxygen can be bad news killed a lot of them anaerobic ones Eventually: anaerobic is glycolysis, mitochondria symbiotic relationship between prokaryotic and aerobic bacteria o Leads to an eventual increase ▯ What are the defining features of eukaryotic cells? Membrane bond organelles: nucleus, mitochondria, chloroplasts (plants), ER, Golgi Linear nuclear DNA associated with histone proteins ▯ What is the endosymbiont theory of how eukaryotic features evolved from prokaryotic cells? Steps: o 1. Start with two independent bacteria o 2. One bacterium engulfs the other o 3. One bacterium now lives inside the other o 4. Both bacteria benefit from the arrangement o 5. The internal bacteria are passed on from generation to generation ▯ What is the evidence for the endosymbiotic origin of mitochondria and plastids? The inner and outer membrane of mitochondria and chloroplasts, inner are more similar to outer of prokaryotes (autotrophic for chloroplasts and aerobic for mitochondria) Must double the organelles to reproduce: o Mitochondria and chloroplasts reduce, and prokaryotes reproduce by binary fission Protein synthesis in mitochondria and chloroplast is similar to protein synthesis in prokaryotes ▯ What did the evolution of muticellularity make possible? Specialization ▯ Why were multicellular eukaryotes limited in size and diversity until the late Proterozoic (ca. 570 MYA)? Water is the environment so minerals and nutrients in, wastes out all through the membrane If you have a bunch of cells together that start to get thick, hard for interior cell to get stuff and get rid of wastes Need circulatory system in order for the organism to get larger Being able to have diffusion in and out of the cell limits the size until there is a transport system ▯ What is the “snowball Earth” hypothesis? various times when earth was frozen, life survived near thermal vents, equatorial areas ▯ What was the Cambrian explosion (535 to 525 MYA)? Ediacaran organisms were small and soft bodied Cambrian was when major lineages of all animals were established ▯ What sorts of adaptations were associated with the colonization of land by plants? Water organisms don’t have to worry about drying out but organisms on land need to worry about water ▯ What sorts of adaptations were associated with the colonization of land by plants? ▯ What was the deal with fungi? ▯ What was the deal with arthropods? ▯ What was the deal with tetrapods? ▯ When did humans show up? 2.5 million years ago ▯ ▯ ▯ ▯ Vocab: ▯ Taxonomy: classification of organisms ▯ Systematics: the study of and classification of organisms with the goal of reconstructing their evolutionary history and relationships (ex: phylogenetic classification) ▯ Binomial nomenclature: the system of nomenclature in which two terms are used to denote a species of living organism, ▯ PhyloCode: taxonomy all based off of taxonomy (but not that easy and used that much) ▯ Homologous: (of organs) similar in position, structure, and evolutionary origin but not necessarily in function ▯ Morphological homology: A structure found in two (or more) different species, but derived from a common ancestral structure is said to be homologous in those species. The structure may or may not be used for the same function in the species in which it occurs. ▯ Analogous: (of structures) performing a similar function but having a different evolutionary origin, such as the wings of insects and birds ▯ ▯ ▯ Main Points: Do not assume the taxon on the phylogenetic tree evolved from the taxon next to it Phylogenies are inferred from morphological and molecular data o These analyses can reflect evolutionary relationships only if the characters used result from common ancestry ▯ Questions: What is the first and second part of binomial nomenclature? o the first one indicating the genus (category that ranks above species and below family, and is denoted by a capitalized Latin name Leo) o the second the specific epithet (descriptive phrase expressing a quality characteristic of the person or thing mentioned) What are the advantages of using Latin or Latinized? o Was the scientific language, and was used to communicate, and a standardization How is the term taxon used (plural is taxa)? o Can use it any level Why do we classify organisms? o So we can recognize things and know what they are How is this type of classification done classically? o If they look like one another then they are classified with one another Does it reflect historical evolution? o No not really What do phylogenic tress purport to show? o Helps show relatedness due to ancestral history o Hypothesis about evolutionary relationships Why is it a hypothesis? o Much of it is used with scientific guesses and DNA sequence data, not all the evidence is there Things that have a lot of differences in nucleotide sequences? o Panther and wolf Similar? o Coyote and wolf Slide 66: Phylogenic tree fill in the blank o 1 common ancestor of all of the things o 2 where lineage divides o 5 forms a polytomy: an unresolved pattern of divergence o B /C sister taxa Are two things that come from the same common ancestor and they are tip ends of the phylogenetic tree o G basal taxon The thing that split of first, the most ancient lineage in the tree What we can and cannot learn from phylogenetic trees: o Can: patterns of descent o Cannot: phenotypic similarity Crocodiles are more closely related to? But look more like? o Birds, amphibians What does this show about morphological homology? (slide 98) o All of their bone structures are similar the structures as limbs, then allow us to conclude that they go back to common ancestor All of them are tetrapod’s o How can we tell they are homologous? They have similar structure? o If we were to look at gene sequences and other DNA sequences from these organisms, what do you think we would find? A lot of differences and similarities (all mammals) DNA sequences of sharks vs. DNA sequences of whales? o Our common ancestry goes farther back in time than the common ancestry of mammals all animals lead to similarities, but also a lot of change because this connection is farther back in time o Differences as well because a whale I a mammal and a shark is a fish As flying organs what is the deal with bat and bird wings? o Rather than being homologous (as limbs are), they are analogous convergent evolution Likewise, as flying organs, bat wings, bird wings, and butterfly wings are _____________ and the result of ________________ o Analogous structures and convergent evolution What’s the deal with the Australian mole and the north American mole? o Entirely different group of mammals Bat wings vs. bird wings? o Homologous as limbs o Analogous as flying organs When are morphological structures more likely to be homologous? o When they have evolved more recently, have a closer common ancestor When are genes more likely to be homologous? ▯ ▯ Vocab: ▯ ▯ Key Concepts: Many of the adaptations that appear to have emerged after land plants diverged from their algal relatives facilitated survival and reproduction on dry land Plants have a hierarchical organization consisting of organs, tissues, and cells Different meristems generate new cells for primary and secondary growth The four key traits of land plants: o Alternation of generations and multicellular, dependent embryos o Walled spores produced in sporangia o Multicellular gametangia o Apical meristems The presence of land plants has enabled other life-forms – including animals – to survive on land ▯ ▯ Questions: What do animals get from plants? o The base of a food chain is a primary producer plants Explain plant cycle: o Sporophyte (2n) spores (n) ▯