kingdomsdomains 1. prokaryotes1a. archaebacteriaarchaea 1b. eubacteriabacteria
DESCRIPTION
DIVERSITY OF LIFE. Current species are classified into 3 Domains and/or 5-6 Kingdoms. KingdomsDomains 1. Prokaryotes1a. ArchaebacteriaArchaea 1b. EubacteriaBacteria 2. ProtistsEukarya 3. Plants 4. Fungi 5. Animals. Major groups are related. All alive today. - PowerPoint PPT PresentationTRANSCRIPT
Kingdoms Domains 1. Prokaryotes 1a. Archaebacteria Archaea
1b. Eubacteria Bacteria2. Protists Eukarya3. Plants4. Fungi5. Animals
Current species are classified into 3 Domains and/or 5-6 Kingdoms
DIVERSITY OF LIFE
Major groups are related
All alive today
All equally “evolved”
But also represent different depths of branching, time since shared common ancestor
Diversification also involved a series of innovations that added new forms of life
Older modes persisted, possibly largely unchanged
“advanced” vs. “primitive”
Diverse species appeared then went extinct
Current diversity is a slice of a continuing process
3-1
1. Prokaryotes (bacteria)single celled DNA, lack nucleusno organellesmotility, incl. flagellaclosest to early life?
No sexual reproduction (meiosis) per se, but various modes of genetic exchange
Prokaryotes
The real “tree” of life?
Much of biochemistry evolved in this group
__________ (“self feeding”) – use CO2 as carbon sourcechemoautotroph – energy from chemicals (e.g. H2S)photoautotroph – energy from sun - photosynthesis
___________ (“other feeding”)– use organic molecules for carbon and energy
anaerobic – respiration without O2
aerobic – respiration with O2
Prokaryotes
Both respiration and photosynthesis started here
Cyanobacteria (“blue-green algae”) are free living and photosynthetic
contain chlorophyll a, ancestor of __________
Prokaryotes
Some bacteria and cyanobacteria can also fix ________
Prokaryotes
Also involved in other Nitrogen transformations (discussed later)
In aquatic and terrestrial systems
Even in some plant roots
Important as ________________
Often closely related species
and Pathogens
Archaea – extreme environments – salty, high temperature
Prokaryotes
http://www.ocean.udel.edu/kiosk/bsmoker.html
Archaea – “ancient”, origin of life?
“Black smoker” (hydrothermal vent)
Prokaryotes
Eukaryotes – Protists, Plants, Fungi, Animals
_________ and Endomembrane
Organelles – mitochondria and chloroplasts
Sexual reproduction (meiosis)
Multicellularity (tissues, organs)
Sociality
2. Protists – mostly small, single celled & multicellular - Eukaryotes – true nucleus (containing DNA) and endomembrane - Many are heterotrophs, aquatic – highly diverse - Various parasites (e.g., amoebas, malaria, helminths)
Endosymbiotic origin of organelles
Mitochondria - ___________ Chloroplast - ___________
Key biochemistry done by bacteria or their descendants
Includes true ALGAE – single and multicellular forms that are photosynthetic, and mainly ________(main “producers” in _________ systems)
Unicellular algae - contain chloroplasts - chlorophyll a, b, & c
Protists
Multicellular algae – “___________” - various differentiated structures, food conducting systems - not rooted - holdfast (nutrients from water)
Complex life cycles & Sexual Reproduction
Both diploid and haploid phases
Sexual (meiosis) and asexual (mitosis) components
Brown Alga (Laminaria)
Green Alga (Ulva) – haploid & diploid equivalent
What is Diploid? Haploid?
Life cycles often switch between these two states.
The zygote is “diploid” because it contains two complete sets of genes, one “haploid” set from each parent. This means two copies of genes of each gene type (“locus”). The two copies need not be identical (alternate “alleles” are common at each locus)
___________ are haploid and fuse to form diploid zygotes.
What is Meiosis? Mitosis?
When a phase of the life cycle duplicates itself asexually, it is a result of mitosis – the exact copying of the genes.
Sexual reproduction results from a much stranger process, where the diploid produces haploid cells by meiosis. The genes replicate once, then divide twice, creating (four) cells with only one set of genes each (haploid).
Meiosis
“Water Mold” (Oomycota) – mostly diploid
Both haploids and diploids can replicate asexually (mitotically) too
Malaria (Plasmodium) mostly haploid
Recombination – the real point?
At least as important as the production of haploid cells, is the recombination of alleles in meiosis. Before making haploid cells, the dividing cells undergoing meiosis essentially “shuffle” the two parental genotypes, creating new genotypes that are mixtures of the parents. Often, the resulting recombinant haploid gametes are fused with gametes from other individuals (___________) to make the zygotes. This creates new genetic variation. The offspring are different from each other and from either parent.
Independent assortment
Crossing overShuffling whole chromosomes(chromosomes = blocks of genes) Shuffling genes
within chromosomes
The paradox of sex - why meiosis?
We have emphasized that evolution favors organisms (autocatalysts) that are good at transforming resources into more self – but here is a widespread mode of reproduction that seems designed to create offspring that are different from the parents, that are deliberately NOT self.
Why? It is assumed there are good reasons, we just don’t know what they are for sure. But of course there have been many proposed explanations (hypotheses).
This is another good example of the difficulty of verifying functional explanations.
The Main Contenders1.
a.
b.
2. a.
b.
3.
4.
5.
3. Plants - primarily terrestrial, multicellular - evolved from ________________ - photosynthetic (chloroplasts), rooted in soil (nutrients) - extensive _____________ tissue - widespread, diverse
Mosses and related species
Ferns and others
Includes tree ferns, once dominant
Coal Age – Carboniferous 290-360 MYBP
Petro future here
= _______ years
http://www.eia.doe.gov/oiaf/ieo/oil.html
How long will current oil supplies last?
Gymnosperms (conifers and others)
Ginko
Cycad Welwitschia
Read Sacks
Conifers
Angiosperms – flowering plants
Include most plants that dominate landscapes today
4. Fungi - eukaryotic, diverse ____________ - unicellular (yeast) and multicelled (mushrooms) - with bacteria, the most important _________ (nutrient releasers) in aquatic and terrestrial systems
Read Sacks
4. Fungi
- important __________, plant root fungal symbionts that enhance nutrient and water uptake
- many fungi are plant & animal pathogens (mostly plants)
4. Fungi- include photosynthetic _______ – a symbiotic association of a fungus and a green algae. Fungus gets carbohydrates for photosynthesis of algae. Live on bare substrate (rock, bark), tolerate drying.
Largest organism?
Blue Whale
Honey mushroom (Armillaria ostoyae) – one genotype
Aspen clone (Populus tremuloides) – one genotype
Giant sequoia
5. Animals - evolved from ________ - multicellular, heterotrophic eukaryotes - 35 “body plans”, most invertebrates, many marine - highly elaborated tissue and organ systems - herbivores, carnivores, parasites
Sponges
Jelly
Anemone
RotiferChiton (Mollusk)
Sea Slug (Gastropod)
Scallop (Bivalve)
Cephalopods: Nautilus & Octopus Leech (Annelid)
Sea Star
Corals - _______________ - have a symbiotic association with “zooxanthellae” which are themselves a symbiosis of a dinoflagellate (protist) and photosynthetic cyanobacteria (prokaryote).
Arthropods
Trilobite (extinct)Horseshoe Crab
Lobster
Shrimp
Barnacle
Trilobites developed one of the first advanced visual systems in the animal kingdom. This may have promoted the spectacular diversification of animals.
Compound eyes in living arthropods such as insects are very sensitive to motion, and it is likely that they were similarly important in predator detection in trilobites. It has also been suggested that stereoscopic vision was provided by closely spaced, but separate eyes
http://www.trilobites.info/eyes.htm http://ebiomedia.com/gall/eyes/octopus-insect.html
The majority of trilobites bore a pair of compound eyes (made up of many lensed units)
Trilobite Optics
Astaynax
Yamamoto Y, Stock DW, Jeffery WR (2004) Hedgehog signalling controls eye degeneration in blind cavefish. Nature 431:844-847.
crayfish
Some Trilobites “lost” vision, as have many existing species
The eyes of the Octopus and Squid (Cephalopods) are very similar to ours in structure and function, with lens and image forming retina.
Read Williams
http://en.wikipedia.org/wiki/Evidence_of_evolution
Eyes of the vertebrates and cephalopod molluscs (squid and octopus) are remarkably similar, an example of ___________evolution. One interesting difference – vertebrates have an inverted retina, the sensory cells lying beneath the nerve fibers. This results in the sensory cells being absent where the optic nerve is attached to the eye, thus creating a blind spot. The octopus eye has a non-inverted retina in which the sensory cells lie above the nerve fibres. There is therefore no blind spot in this kind of eye.
The Blind Spot The blind spot is the area on the retina without receptors that respond to light. Therefore an image that falls on this region will NOT be seen. It is in this region that the optic nerve exits the eye on its way to the brain.
http://staff.washington.edu/chudler/chvision.html
In the next two images, close your right eye. With your left eye, look at the numbers on the right side, starting with the number "1." You should be able to see the "sad face" (top image) or the gap in the blue line (bottom image) in your peripheral vision. Keep your head still, and with your left eye, look at the other numbers. The sad face should disappear when you get to "4" and reappear at about "7." Similarly the blue line will appear complete between "4" and "7.“ This is because your brain is "filling in" the missing information.
Here is another image to show your blind spot. Close your right eye. With your left eye, look at the +. You should see the red dot in your peripheral vision. Keep looking at the + with your left eye. The red dot will move from the left to the right and disappear and reappear as the dot moves into and out of your blind spot.
Arthropods – Spiders and Insects
Vertebrates (Chordates)
Animals - Sociality
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End Part 3