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Bio 230 Notes Fusun Dikengil 1 Traditional Hypothesis Luca - the last universal common ancestor, “original organisms” close to archaea New-er Hypothesis “horizontal gene transfer” There is evidence that many of our genes and DNA has been transfered by virus’s and other things into us, by over a period of time. Things that occur way early on are not rare, and still occur today. Evolutionary Advances, Developments, and Trends Cell Complexity Prokaryote ---> Eukaryotes Prokaryotes did not have a nucleus but have DNA. Prokaryotes go back to 3.5-3.8-4.0 billion years ago. Eukaryotes evolve about 2.2 billion years ago. The first Eukaryotes started off as unicellular. Within eukaryotic cells you find a really fascinating organelle called a mitochondrion. And in plant cells, you'd find an additional family of organelles called plastids, the most famous of which is the renowned chloroplast. Mitochondria (the plural of mitochondrion) and chloroplasts almost certainly have a similar evolutionary origin. Both are pretty clearly the descendants of independent prokaryotic cells, which have taken up permanent residence within other cells through a well-known and very common phenomenon called endosymbiosis. or in other terms: Evidence supports the idea that eukaryotic cells are actually the descendants of separate prokaryotic cells that joined together in a symbiotic union. In fact, the mitochondrion itself seems to be the "great-great-great-great-great-great-great-great-great granddaughter" of a free-living bacterium that was engulfed by another cell, perhaps as a meal, and ended up staying as a sort of permanent houseguest. The host cell profited from the chemical energy the mitochondrion produced, and the mitochondrion benefited from the protected, nutrient-rich environment surrounding it. This kind of "internal" symbiosis — one organism taking up permanent residence inside another and eventually evolving into a single lineage — is called endosymbiosis. Serial Endosymbiosis Theory Explained by Dr. Belzar: • Serial means there is a series that occurred, like a tv. show. Endo means something within, symbiosis means things that work together in some way or another, and theory..because we have a lot of evidence to support this. The chloroplasts and mitochondria have an X type of origin, they came from the outside. The nucleus has an endogenous origin, a self origin. In pocketing of the plasma membrane/cell membrane exist to prove the X type of origins invaded or entered. We even see some prokaryotes some of these indentions semi-surround the chromosome. All the other organelles were exogenous, they came from the outside. They are organisms that invaded this. Dr. Belzar then changes slides, and puts on a map from our packets, of monera, the page that explains endosymbiosis “A map of Serial Endosymbiosis Theory by Lynn Margulis. At the bottom of it are prokaryote types that followed by the development of a nucleus, next came mitochondria and finally plastids. What is not evident in the diagram is the face that plastids arose more than once. If nucleu arose more than once then the present day eukaryotic assemblage is polyphyletic.” - From the hand out Bio 230 Notes Fusun Dikengil 2 What she is saying here is that the basic eukaryotic cell, would be most like (not identical too) current day thermoplasmas (a type of archaea). That the mitochondria might be similar to paracoccus/basically bacteria, which are aerobic, once they got inside they got aerobic metabolism inside this other cell. Flagella, cillia, Lynn likes to call them ungulapoduelum. The word flagella isn’t as specific as it could be. Bacteria have flagella, Protists, human sperm have flagellum, turns out that eukaryotic flagellum and the bacterial flagellum are completely different structures. The eukaryotic flagellum have all the microtubules in them, and they slide on each other and has motility within itself. The bacterial flagellum, completely different groups of proteins, has no motility or microtubules. Its the structure that meets the cell that moves it. Like an oar and a paddle moving a boat, completely different. It completely ungulates itself, lynn leaves the word flagellum just for the bacteria. Now, what about cillia? There is no “real” difference, the big one is usually when you have “flagella” in eukaryotes, rather few, are long. Cillia, are short, and usually dozens, hundreds or thousands. Otherwise, they have exactly the same structure and everything else. Lynn also believed that flagellum, or ungulagellum comes from spirochetes bacterium. The ungulate themselves, wiggle and move around almost similar. These kind of co-opeartions between organisms are new, or rare. Chlorophyl might be derived from the type of chloroxybacteria, as in the hand out. 20:31 what’s not in your notes: Primary endosymbiosis- Primary endosymbiosis involves the engulfment of a bacterium by another free living organism. Secondary endosymbiosis occurs when the product of primary endosymbiosis is itself engulfed and retained by another free living eukaryote. keywords: changing over a period of time, membrane layers Organism Complexity Unicellular--> Colonial-->Multicellular Colonial are aggregates of other cells, sometimes have def. shapes, plates, one cell layer thick, rectangular, filaments, but they don’t have cell to cell cytoplasmic connections. Not hardwired together. But cells communicate to some extent, substances diffuse from cell to another. I think these cells look the same. Multicellular- Bunch of cells, are hard wired, have the cytoplasmic connections. True multicellular cells are eukaryotes. substances just don't have to diffuse from environments, they have a chemical pathway instead (hardwired) A colony of single-celled organisms is known as a colonial organism. Colonial organisms were probably the first step towards multicellular organisms via natural selection. The difference between a multicellular organism and a colonial organism is that individual organisms from a colony can, if separated, survive on their own, while cells from a multicellular life form (e.g., cells from a brain) cannot Advantages: Bio 230 Notes Fusun Dikengil 3 1. multicellular organisms, cells can specialize Disadvantages: 1. If one of those special cells goes on strike, your screwed Organism Size Small---> Large----> [less large?] • Evolution shows size over time can also reduce. ex. insects ----------------------------------------------------------------------------------------------------------------------------------------- Organism Lifespan Short--->Long--->Shorter? • Some sunflower plants that go from seed to flowering, in 3-4 weeks (a whole generation). Those seeds can then germinate, and over a season can go through 4 or so generations. There is an advantage through quicker life cycles, you can go through more generations through a particular part of time. You can mix and match genes and come up with new combinations. more generations better combinations. ----------------------------------------------------------------------------------------------------------------------------------------- Type of Nutrition Heterotrophic---> Autotrophic • First organisms were heterotrophic, could not make their own foods • Foods are energy rich organic molecules, contain nutrients, contain energy in bonds • Plants, make foods, so Autotrophic, which came later, make foods fron inorganic substances, don’t eat they make food • As materials were lost in supply, organisms were able to adapt and use molecules that were abundant (hence autotrophs) 1. Heterotrophic 2. Anaerobic Chemoautotrophic- Don’t use sunlight energy, as the energy source to charge their battery, to put in the bonds of those organic molecules. Works under oxygen-less conditions. Inactivated or killed by oxygen. Methanogens- use methane, (bacteria) They will take energy that they get from breaking down, doing something to relatively simple inorganic compounds. When that energy is released, they use that instead of sunlight energy to make their organic molecules. (sugars ect.) 3. Phototrophic (=photo-autotrophic)- energy comes from sunlight (photosynthetic) Type I-- Non-oxygenic (only found in bacteria) - Don’t release oxygen as a byproduct - Hydrogen sulfide as the hydrogen source (to make glucose), sulfur is left Type II-- oxygenic (found in cyano-bacteria and Eukaryotes) Bio 230 Notes Fusun Dikengil 4 - what we are familiar with - uses water as the hydrogen source, produces oxygen - Any organism with chlorophyl A 4. Aerobic Chemoautotrophic ---------------------------------------------------------------------------------------------------------------------------- Genome Content Haploid---> Diploid Haploid- 1 Copy of a chromosome in the nucleus Diploid- have pairs, 2 pairs These terms only refer to Eukaryotes, because copies are found in the “nucleus” Well, if we stretched the term a bit, we consider bacteria to be haploid like. Circular chromosome, and 1 copy of it. Haploid Eukaryotes have multiple chromosomes, but only 1 of each type, so hypothetically 1 copy of each of their genes. Diploid do not have twice as many genes as in a sperm or egg, they have the same number just 2 copies of each gene. Disadvantage: if Haploid, 1 copy, if something happened to it = not good ----------------------------------------------------------------------------------------------------------------------------------------- Type of Nuclear Division Process Mitosis & Meiosis (zygotic, Gametic, Sporic) Bacteria do not have mitosis. Do not confuse mitosis and cytokinesis, the 2 process of mitotic cell division. We have muscle cells that are multi-nucleated. Where did they get the other nucleus? The nucleus divided, but the cytoplasm didn’t. Those two process don’t have to occur together. Mitosis- Takes w.e genetic material is there, makes the duplicate, separates it. Like photocopying something. 1 thing -> makes it into 2, and everything identical, very conservative, keeps things static. Keeps things the same. Meiosis- Whatever genetic material is present, gets replicated, then goes through 2 division. goes from 1 to 2, then to 4. So that means those 4 products have half as much DNA. Can only occur in diploid nuclei. 2 -4 -1-1-1-1 Diploid to Haploid. All products are not identical, variation. ------------------------------------------------------------------------------------------------------------------------------ Zygotic Meiosis- has something to do where meiosis occurs in the life cycle. Considered most primitive type. A Cycle, the beginning is wherever you want to start. In our case, we will start with the gametes. Gametes are always haploid, 2 of those come together (not referred to as egg and sperm, b/c of different organisms. Some have gametes that you can’t even tell the difference between) ultimately you get a zygote thats diploid. Then, they undergo meiosis and go back to haploid conditions (the zygote). Sexual reproduction is here, and instills variation Bio 230 Notes Fusun Dikengil 5 Life cycle type: Haplobiontic Haploid -----------------------------------------------------------------------------------------------------------------------------Gametic Meiosis- gametes are always haploid. Type found in some animals, and some protists. Starts by 2 gametes that form a zygote, but then the diploid zygote undergoes mitosis and copies itself 2n -> 2n. But then this time, meiosis occurs (during sexual reproduction) to make the haploid gametes, hence why its called gametic meiosis. 2n--> 1n + 1n Life cycle type: Haplobiontic Diploid ------------------------------------------------------------------------------------------------------------------------------ Sporic Meiosis- In plants, and some protists. meiosis occurs here in the formation of spores. Starts with haploid gametes, 2 of them come together in fertilization and form a zygote, then that zygote undergoes mitosis that makes an organism thats diploid. (diplophase) somewhere, they undergo meiosis, but instead of gametes, they form spores (haploid). The spores undergo mitosis to make a haploid individual (the alter ego thing). Then later on, that haploid individual by mitosis make the gametes (haplophase). Gametes (2)-->Zygote (2n)--->Organism (2n)--> spore (n)--> Organism (n)----> Gamete Fertilization ^ Meiosis^ Mitosis^ Life cycle type- Diplobiontic -----------------------------------------------------------------------------------------------------------------------------Life Cycle Type Definitions: Haplobiontic Haploid- One main phase in the life cycle of the organism. In that main phase the nuclide in it are haploid. Haplobiontic Diploid- One main phase in the life cycle of the organism. In that main phase the nuclide in it are diploid. Diplobiontic- It has 2 main phases in it’s life cycle. An alter-ego in a way. -----------------------------------------------------------------------------------------------------------------------------In an organism with diplobiontic life cycle it can be: Isomorphic- Both phases look the same (diplophase and haplophase) or Heteromorphic- The n and 2n phase are different (hetero meaning other forms) If the species has a heteromorphic diplobiontic life cycle then it can have either the haploid phase dominant or the diploid phase dominant. ------------------------------------------------------------------------------------------------------------------------------ Mode of Reproduction Asexual--> Sexual [?? --- Asexual] Bio 230 Notes Fusun Dikengil 6 Bacteria are all asexual no matter what. We do knew they can pick genes outside of themselves, we know that 2 bacteria can join with a little bridge (conjugation) or dna transfer, or broken down. None of this is sexual reproduction however. The first Eukaryotes (organisms) were asexual. Sexual reproduction came later so it was considered more advanced. However, in certain groups way back in their lineage, some started as asexual, then became sexual and then it was either suppressed or lost (back to asexual) Sexual Reproduction Advantages- More combinations, you never know what would be needed as conditions change. You will never know what your going to get, no guarantees, if you keep photocopying (mitosis) its guaranteed no genetic variations. You get a better chance of one of them being better fit for new conditions Disadvantages- Breaking up previous combinations and making new ones. What happens if you break up a good combo? It fits them for this set of conditions, when they reproduce their offspring may not be as fit. Variation can be good or bad. Sexual reproduction seems to work out better more times. Asexual works for extremely static environments, because they are essentially cloning themselves. SO if one is fit, they are all fit. If conditions change somewhere down the line, they’re all unfit. End of Monday Feb 2nd Video -----------------------------------------------------------------------------------------------------------------------------Beginning of Feb 3rd Video Sexual Reproduction as Regards Gamete Differentiation Isogamy------->Anisogamy------>Oogamy Isogamy- Gametes look the same, can’t call one a sperm and the other egg, no male and female, more primitive organisms have. Not necessarily identical, many times they have what we call plus and/or minus strands since we can’t call them male and female, and look the same. If we cloned one lets say, we would find 2 of them would never fuse because they are the same strains. Usually both are small and motile in size. Anisogamy- Look a little different, usually find for example one is small and quite motile and the other would be a bit larger and a bit more sluggish. You begin to see a little bit of development. Oogamy- What we are familiar with, usually the motile small sperm, and the much larger nonmotile egg. Each of those are genetically equivalent, haploid set of chromosomes. Note: a sperm doesn’t have to motile to be oogamanous. ------------------------------------------------------------------------------------------------------------------------------ Number of Offspring & Protection Many ---> Few More primitive organisms usually tend to have many offspring, those that have the many offspring usually don’t give that much protection to the reproductive process. (shot gun approachif you shoot enough, you might hit something) Bio 230 Notes Fusun Dikengil 7 Evolved organism tend to produce fewer offspring, with more internal protection, higher chance or survival.External Fertilization: Very dependent on water in the environment, if its not a true aquatic system then they need a film of water somewhere so that sperm can swim to egg to accomplish fertilization Higher animals like ourselves are not dependent on water in the general environment, due to internal fertilization. Higher plants have also gotten rid of that need for that film of water in the environment. That takes the guesswork and hazards out of sexual reproduction. -----------------------------------------------------------------------------------------------------------------------------Evolutionary Ideas: Please turn to a comparison of view on variation and heredity provided in the packet and read it Evolutionary Mechanisms & People: Empedocles- 490 to 430 B.C • First that we know of, (evidence) to propose a clear concept of biological evolution. • Believed in abiogenesis, or spontaneous generation (living things that can come from nonliving things). • Plants arose first, and that animals came later. Changes were gradual. Aristotle- 334-322 B.C• Believed in the fixity of species. Whatever they are today, is pretty much the way they always were. • Also believed in abiogenesis. • Acquired characteristics- things that organisms picked up in there lifetime could be passed onto future generations • Species could hybridize. (At that time, horses + humans = centaurs. Much different hybridization) Lamarck- 1744 -1829 • First in more recent times, to put a more comprehensive evolutionary hypothesis. • Did believe in acquired characteristics (tailless mice, neck stretching, webbed-toes) this developed on a thing called pangenes (little particles or vapors would migrate to the reproductive organs, came from all over the body.) Pangenesis holds that body cells shed gemmules, which collect in the reproductive organs prior to fertilization. Thus every cell in the body has a 'vote' in the constitution of the offspring. • Organisms were always improvements of the past Malthus- 1823- 1913• Studied human populations- Demographer • Had a background on economics. • Inspired Darwin Bio 230 Notes Fusun Dikengil 8 Wallace• British Naturalist • Similar ideas like Darwin C. Darwin- 1809-1882• Natural Selection, (was actually a creationist) everything was made in it’s present form. Idea was from Malthus’s essay in 1838, this essay said that humans in population had the potential to grow faster than the support system (ex. the economy, industry) Darwin thought, too many people..not enough stuff, who’s going to live? Those that are able to get it. Why does this just apply to humans? He connected them to everything. Survival of the fittest. • 1858- Receives letter from Wallace, in that letter is basically what Darwin’s been working on for the last 30 years. Points of natural selection. Modern Synthetic Theory People: T. Dobzhansky- “married” or brought genetics into evolution and showed where variation could come from in depth E. Mayr- Animal evolution C. Babcock- UCLA plant evolutionist E. Anderson- Botanist, Introgressive hybridization, 2 related species could hybridize, and that the hybrid could have some fertility but could go back to one or the other of the parents. (A + B = AB --> A then to ---A then a organism that could be completely species A but one or two traits from B), Introgressing back to one of the parents type G.L. StebbinsWatson and Crick- Structure of the DNA Nirenberg & Matthaei- Worked out the genetic code Neo-Darwinism (= Modern Synthetic Theory) Neo-Darwinism is a term used to describe certain ideas about the mechanisms of evolution that were developed from Charles Darwin's original theory of evolution by natural selection: while separating them from his hypothesis of Pangenesis as a Lamarckian source of variation involving blending inheritance. ---> http://en.wikipedia.org/wiki/Modern_evolutionary_synthesis ----------------------------------------------------------------------------------------------------------------------------------------- Darwin’s Ideas A. Overproduction of offspring- All species have the capacity to produce more offspring than the area or ecosystem can support. B. Variation among individuals- Some of the differences have a genetic basis, not necessarily all. All organisms start with a certain genetic endowment- code of what we can achieve (someone who could’ve been 6ft but didn’t have the support system, but still had that quality) ---- MVI_2626.AVi pause at 0:37:11 Bio 230 Notes Fusun Dikengil 9 C. Limits on ResourcesD. The Fittest Survive E. Accumulation of favorable traits and the elimination of less favorable ones lead to evolution.