Download Bio 230 Notes Fusun Dikengil 1 Traditional Hypothesis Luca

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
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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.
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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
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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
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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.
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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
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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.
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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.
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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
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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.