EEMB 3 Flashcards
Gaia Hypothesis
Earth is a living entity and it regulates and maintains climate and atmosphere at an optimum level.
When were the earliest forms of life found on Earth?
3.5 - 3.8 bya
What are the essential characteristics of life?
- Membranes
- Aqueous system
- Monomers to macromolecules
- Information carriers (RNA & DNA) and translation apparatus
- Energy storage and flow
- Catalysts
What did Francesco Redi discover?
Though his experiments with exposed and sealed jars of meat, he found that life generates life.
Louis Pasteur
Discovered that airborne microbes are responsible for the decomposition of organic matter though his experiment with curved tubes leading to a flask.
- Pasteurization
- Contributed to theory and practice of vaccination.
Panspermia Hypothesis
The theory that life exists and is distributed throughout the universe in the form of germs or spores, and that life on Earth originated through extraterrestrial means.
Chemical Evolution Hypothesis
Origin of life can be viewed as four overlapping stages:
- Nucleotides and Amino Acids before cells.
- Nucleotides and AA’s polymerize → DNA, RNA and proteins.
- Polymers enclosed in membranes.
- Evolution of cellular properties.
Extraterrestrial Input Hypothesis
Organic matter and water brought to Earth via asteroid and comet collisions.
Reducing Atmosphere Hypothesis
Or Chemical Evolution
- Hypothesis formed in the 1920’s by Oparin and Haldane whereby nucleotides and aa’s occured naturally.
- Volcanic gasses created a strongly reducing atmosphere.
- Little or no O2
Miller-Urey Experiment
Discovered that in a reducing atmosphere containing methane, carbon dioxide, ammonia, hydrogen and nitrogen, but without oxygen–nucleotides and amino acids naturally form.
Hydrothermal Vent Hypothesis
Temperature gradients and plume chemistry led to the formation of organic molecules.
Changes in living organisms are a result of what two interactive processes?
- Genetic Exchange
- Environmental change
How did macromolecules form from monomers without the aid of enzymes?
Condensation reactions (Terminal OH and H on separate monomers react to combine and leave water as byproduct).
What are three plausible location for initial polymerization without the aid of enzymes?
- Solid mineral surfaces
- Hydrothermal vents
- Hot pools
Protobionts
Aggregrate of abiotically produced organic molecules that can have metabolism.
Coacervate
A tiny spherical droplet of assorted organic molecules (specifically, lipid molecules) which is held together by hydrophobic forces from a surrounding liquid. Cannot reproduce.
What role did RNA play in a pre-DNA world?
RNA acted as both:
- Information carrier, and;
- Catalyst
Through fossils’ _____ relationship, people can determine the relative ages of fossils.
stratigraphic
- Similar types of fossils found within strata in widely separated parts of the earth.
- Major changes in fossil types in the rock strata used to define time periods.
Absolute dating is determined through what method?
Radioactive decay
- Radioactive isotope decay over regular equal periods of time.
- If you know how much isotope existed at the beginning and you know how much remains you can calculate the age of the sample.
What are the 5 geologic and biogeochemical changes that affected extinction and evolution?
- Continental drift - sea level drop
- Climate change
- Volcanic activity
- Unidirectional flux in O2
- External events
What are three common features that all microbes share?
- They live in water-rich environments
- They’re a food source for higher trophic levels.
- All are small!
What are some important consequences of microbes’ small size?
- Small size leads to high surface area to voume ratio.
- Higher proportion of metabolically active body components.
- Higher growth rates.
Although phytoplankton account for only 0.2% of all living plant matter on earth, they are responsible for __% of the earth’s photosynthetic activity.
45%
_____ _____ bacteria are the base of the food web around hydrothermal vents.
sulfur oxidizing
Of all the biogeochemical cycles, the _____ cycle is the one most intimately and throughly associated with microbes.
nitrogen
Van Leeuwehoek
Was the first scientist to observe bacteria and protists, though the use of a crude microscope.
Magnification
Produces a larger image but provides no additional detail.
Resolution
The distance between 2 objects that allows one to discern them as separate; increased resolution causes increased detail and information.
Robert Koch
- “The Father” of medical microbiology.
- Developed the pure culture technique–assumed colonies with different shapes and colors were derived from different microbes.
- His postulates led to his “germ theory,” proving that diseases were caused by microbes.
Alexander Flemming
Discovered penicillin through fungal spores that grew on his uncovered petri dish(es).
Sergei Winogradsky
An environmental microbiologist who was the first to develop idea of chemolithotrophy.
Chemolithotrophy
Organisms obtain their energy from the oxidation of inorganic compounds and use CO2 as their carbon source…they are autotrophs.
Martinus Beijerinck
An environmental biologist who discovered enrichment cultures.
- Set up culture with all inorganic compounds except Nitrogen; if microbes were to grow they would have to fix N.
Kary Mullis
Won the Nobel Prize in Chemistry in 1993 for creating the now widely-used Polymerase Chain Reaction.
Thermus aquaticus
A microbe discovered by environmental microbiologists Thomas Brock and Hudson Freeze to contain Taq polymerase, a heat stable polymerase.
Norm Pace
Created cultivation independent techniques
- 16s rRNA gene clone library construction
What are the four steps to identifying an organism via rRNA genes?
- Isolate plasmids from clones
- Sequence rRNA gene ligated in plasmid
- Align sequence data to assess variability
- Construct phylogenetic relationship
Prokaryotes have approximately _____ as much DNA as eukaryotes.
1/1000
What are the three mechanisms for prokaryotic genetic recombination?
- Transformation: the genetic alteration of a cell resulting from the direct uptake, incorporation and expression of exogenous genetic material
- Conjugation: the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells.
- Transduction: the process by which DNA is transferred from one bacterium to another by a virus
How do you differentiate between bacteria and archaea cell membranes?
Bacteria:
Phospholipid bilayer w/fatty acids.
Ester linkage.
Peptidoglycan cell wall (muramic acid).
Archaea:
Phospholipid bilayer w/o fatty acids, isoprene instead. Some have monolayer.
Ether linkage.
No peptidoglycan
What are the differences between gram + and gram - cell walls?
Gram + : Simpler cell wall
Less physiologically diverse
Can produce exotoxins
Gram - :More complex, lipopolysaccharides (LPS) attached.
Can produce endotoxins
Anobolism
The biosynthensis of new macromolecules from monomers and/or polymers and an energy source (like ATP).
Catabolism
The set of metabolic pathways that break down molecules into smaller units and release energy.
Cyanobacteria
- Obligate photoautotrophs
- Photosystem II
- Light for energy source
- Oxygenic process (source of O2 on Earth)
- Some form colonies
- filamentous colonies
- vegetative
- spores
- heterocysts
- filamentous colonies
What microbes are most commonly found under a chemoautotrophic metabolic pathway?
Archaea
The majority of prokaryotes have a ______ metabolism.
chemoheterotrophic
Pseudomonads
Generic gram - heterotroph
- Aerobic
- Fast growing
- Use simple compounds
Psychrophiles
Prokaryotes that live in the low temperature range of 0 - 20 ºC
Mesophiles
Prokaryotes that love in the middle temperature range of 20 - 48 ºC.
Thermophiles
Prokaryotes that live in the high temperature range of 42 - 68 ºC
Hyperthermophiles
Prokaryotes that live in the very high temperature range of 65 - 110 ºC.
Proteobacteria
Largest and most diverse group. Likely the source of mitochondria in eukaryotes.
Purple Bacteria
Photoautotrophic and photoheterotrophic
Rhzobium
Nitrogen fixing symbiont bacteria.
Enteric Bacteria
Inhabit the intestinal track, facultative anaerobes.
- E. Coli
- Salmonella
- Y. pestis
Crenarchaeota
Archaea that includes hyperthermophiles and acidophiles.
Euryarchaeota
Archaea that includes the methanogens and halopiles.
What are the three processes that all known organisms on Earth use at least one of to generate ATP?
- Fermentation: substrate level phosphorylation–no external electron acceptor.
-
Oxidative or Electron Transport Level Phosphorylation (ETLP):
- Aerobic: uses O2 as e- acceptor.
- Anaerobic: uses NO3-, Fe3+, SO42- and CO32- as e- acceptor.
- Photophosphorylation: The production of ATP using the energy of sunlight.
What were the five main changes in prokaryotic evolution to eukaryotes?
- Loss of cell wall increased flexibility, while membrane infolding increased surface area.
- 1st step to organized nucleus.
- Ribosome studded internal membrane
- Appearance of cytoskeleton–gave physical structure to large cells.
- Formation of digestive vesicles.
- Endosymbiosis of organelles.
Endocytosis
The process of taking in food within vacuoles formed by invagination of the plasma membrane.
- If dissolved, called pinocytosis.
- If whole particle, called phagocytosis.
Symbiodinium
Dinoflagellate endosymbiont with coral.
Radiolarians
Heterotrophs that host photosynthetic endosymbionts.
- Occasionally present is an internal SiO4 skeleton.
Explain the steps of conjugation.
- Two paramecia conjugate; all but one micronucleus in each cell disintegrate. The remaining micronucleus undergoes meiosis.
- Three of the four haploid micronuclei disintegrate; the remaining micronucelues undergoes mitosis.
- The paramecia donate micronuclei to each other. The macronuclei disintegrate.
- The micronuclei in each cell–each genetically different–fuse.
- The new diploid micronuclei divide mitotically, eventually giving rise to a macronucleus and the appropriate number of micronuclei.
Dinoflagellates
- Chromalveolate → Alveolate
- Two perpendicular flagella
- Phytoplankton
- Responsible for red tides
Apicomplexans
- Chromalveolate → Alveolate
- Parasites of animals, with unusual spores.
- Apical co9mplex is defining structure–used to burrow into host tissue or cells.
- Intricate life cycle that requires occupation of 2 hosts.
Coccolithophorids
- Chromalveolate → Haptophyte
- CaCO3 (calcium carbonate) plates, coccoliths
- Autotrophic
- Thickens shell and becomes more abundant under acidic conditions.
- Huge blooms visible from satallites.
Diatoms
- Chromalveolate → Stramenopile
- Contain carotenoids and are golden brown in color.
- Silica shells
- Important phytoplankton (>50% of ocean’s photosynthetic production).
- Both sexual and asexual production
- Harmful algal blooms
- Diatomaceous Earth
Brown Algae
- Chromalveolate → Stramenopile
- Scientific name: Phaeophyceae
- Photoautotrophs
- Fucoxanthin pigment
- Multicellular (seaweeds)
Green Algae
- Plantae → Chlorophytes (exclusively green algae)
- Chlorophylls a and b
- Includes unicellular, multicellular and colonial species.
Red Algae
- Plantae → Rhodophyta (exclusively red algae).
- No flagellated stages
- Key pigment: phycoerythrin.
- phycocyanin, carotenoids, chlorophylls a and c
- All multicellular
- Some secrete calcium carbonate (CaCO3)
Rhizaria
- Eukaryotic supergroup that includes Radiolarians and Foraminifera.
- Primarily marine, some freshwater.
- Many have photosynthetic endosymbionts, but most are heterotrophic.
- Amoeboids with complex shell-skeletons
Excavates
- Mostly heterotrophs
Amoebozoa
Unikonts including the plasmodial slime mold and the cellular slime mold.
Choanoflagellida
- Unikont
- Closest relative to animals
- Cononial
- Similar to sponges
Coenocytic
Fungal mycelia in which the hyphae lack septa.
Haustorium
The appendage or portion of a parasitic fungus (the hyphal tip) or of the root of a parasitic plant that penetrates the host’s tissue and draws nutrients from it.
Arbuscular mycorrhizae are contained within the _____ clade in within fungi.
Glomeromycota
Bacteriorhodiopsin
A protein used by Archaea, the most notable one being Halobacteria. It acts as a proton pump; that is, it captures light energy and uses it to move protons across the membrane out of the cell. The resulting proton gradient is subsequently converted into chemical energy.
What is the difference between a dichromatic and a monochomatic species?
A dichromatic species has two distinct phenotypes corresponding to the two sexes, whereas monochomatic species have but one phenotype.
What are the two main types of asexual reproduction in plants and how do they occur?
- Vegetative reproduction
- Rhizomes (underground shoots)
- TIllers (aboveground shoots)
- Bulblets (little bulbs)
- Bulbils (inflorescent vegetative buds)
- Cuttings
- Agamospermy
- Production of seeds genetically identical to parent plant asexually, w/o fertilization between gametes
- Embryo sac develops without meiosis and the egg is diploid.
Inbreeding depression
The reduction in fitness of inbred offspring in comparison without outcrossed offspring. Manifested by reductions in viability and fertility.
Monoecious
Angiosperm that contain both the male and female organs of reproduction on the same individual plant.
Dioecious
Angiosperms that have only one sex per individual plant.
Common in tropical regions and oceanic islands.
Generally small flower size
100% outcrossing but inefficient
Sometimes controlled by sex chromosomes
Dichogamy
The temporal separation of reproductive parts.
Protandry
Anthers release pollen before the stigma is receptive. Common in insect-pollinated plants.
Protogyny
Stigma is receptive before pollen release. Less common than protandry.
Herkogamy
The physical separation of reproductive parts.
Distyly
Two floral morphs
- Thrum flower w/long filaments and short styles
- Pin flower w/short filaments and long styles.
Only pollinations between different floral morphs are successful
Tristyly
Three floral morphs
- Style long, stamens short and medium
- Style medium, stamens short and long
- Style short, stamens medium and long
Only 3 families
Enantiostyly
Left/right separation of stamen and style.
Flexistyly
Temporal separation of stamen and style.
Cleistogamy
Flowers never open and are only capable of self-fertilization in bud.
Anther-smut disease
An STD among angiosperms that is cause by a fungus that infects an individual and creates false anthers to spread to other flowers.
Hepatophyta
Liverworts
- No stoma
- Thallus (main vegetative body) grows laterally
- Anchored to the substrate by rhizoids
Bryophyta
Mosses
- Has a filamentous stage called the protonema, that later grow leafy green shoots (gametophyte)
- No true leaves.
Lycophyta
Club mosses, spike mosses and quillworts
- Dichotomous branching pattern
- Microphylls arranged spirally
- Sporangia on leaf surfaces, in leaf axils or in strobili.
- Mostly homosporous
Monilophyta
Horsetails, whisk ferns and ferns
- Main stem more dominant than side branches.
Horsetails
- Reduced megaphylls arranged in whorls
- Stems are segmented and usually hollow
- Each segment grows basally
- Sporangia clustered in strobili
- Called “scouring rush” due to their tough stems infused with silica
Whisk ferns
- Have broom-like stems that appear nearly leafless.
- Gametophytes found underground.
- Sporangia found at branch nodes.
- Closely related to Rhynia.
Ferns
- Diverse habits and growth forms
- Horizontal stems called rhizomes
- Fronds are sporophyte generation
- Clusters of sporangia found on the frond undersdes are called sori
- Young fronds called “fiddleheads”
Indusia
Protective structures for the sori.
- True indusium: tissue covering like an umberella
- False indusium: formed from curved margin of the leaf
Fern annulus
A band of specialized cells surrounding the sporangium that releases the spores when it dried out.
Prothallus
A small, flat, delicate gametophytic fern structure that is produced by a germinating spore, which bears sex organs.
Gnetophyta
First plant species to posses vessel elements. Includes 3 eclectic genera:
- Welwitschia: two continuously growing, strap-like leaves
- Gnetum: tropical, everygreen and woody vines
- Ephedra: jointed brances, scale-like leaves
