The Prokaryotes: Flashcards
About how many years ago did the first prokaryotic cells evolve, according to the fossil record?
Earliest prokaryotic fossils about 3.5 BYA.
In the Precambrian Era.
What is the basic idea behind the Oparin-Haldane hypothesis? (1938)
That life arose through abiogenic molecular Evolution
In what ways were Oparin and Haldane’s ideas similar?
-That early Earth was very inhospitable, due to its primitive atmosphere, with intense heat, also agreed sunlight provided the energy with its intense UV.
In what ways were Oparin and Haldane’s ideas different?
- Oparin: atmosphere lots of methane,, water vapor, ammonia and hydrogen gas; intense heat of volcanoes, lightning and sunlight provide the energy; (the formation of coaverates)
- Haldane: atmosphere had water vapor, carbon dioxide, and ammonia; Intense UV from sun since no ozone layer, which provided the energy; (the formation of organic molecules, in a “hot dilute soup,” covering Earth [premordial soup]
Stanley Miller’s 1953 Experiment were designed to test what hypothesis?
his experiments were designed to test Oparin-Haldane Hypothesis, using conditions of early Earth suggested by Oparin
What conclusions did Miller draw from the results of the experiments (1953)?
- Concluded that 15% of Carbon incorporated into 4 kinds of amino acids (which builds proteins), Urea, and fatty acids (which build lipids) [The 15 % is coming from the methane (CH4)]
- Also concluded, the experiment doesn’t work when the atmosphere contains O2, implying early Earth had no oxygen in it (it came later).
what was the key difference between Fox’s “Protobionts/Protocells” and actual living cells?
“Protocells” are like cells, however they can’t reproduce and/or replicate itself/themselves.
Why would it be more likely that nucleic acids evolved before enzymes evolved in living systems? Explain why scientists think that is true:
It is more likely that nucleic acids evolved before enzymes because nucleic acids are easier to build
Which type of Nucleic Acid probably evolved first: RNA or DNA? why do scientists think this is true?
We believe RNA came first, since its easier to build, because you only need 1 strand of nucleotides (which its also a template on how to build a protein)
What is the geographic range of bacteria?
Bacteria are ubiquitous meaning they are found everywhere, all over the place
3 Basic shapes of bacteria cells?
1-Coccus (plural=cocci)—->Round
2-Bacillius (plural=bacilli)—-> hot dog/rod shaped
3-Spirillium (plural=spirillium)–> spiral (corkscrew)
What are Bacteria’s most common Arrangements?
- 1–Strepto–Meaning “chains”/ Chained together
- 2–Staphylo–Meaning “grape-like clusters
- 3–Diplo–Meaning “pairs”
- 4–Sarcina–Cuboidal (packets of 4, 8)
The method of reproduction for bacteria:
- No Mitosis and No Meiosis
- They do a process to replicate itself called Binary Fission (all have same DNA)
What are the Principle differences between Prokaryotic cells and Eukaryotic cells?
- Prokaryotes do not divide by mitosis, instead through binary fission.
- The organization of the genetic material differs, since the DNA of prokaryotic cell is not organized within a membrane enclosed nucleus, they have smaller DNA molecules called Plasmids, and DNA is often circular.
- prokaryotes have none of the membrane-enclosed cytoplasmic organelles—(mitochondria, Golgi apparatus, and others, that are found in most Eukaryotes)
What are the 2 Domains of prokaryotic cells? Which domain is more closely related to Eukaryotes?
- 2 Domains: Bacteria and Archaea
- Eukaryotes share a more recent common ancestor with Archaea, than they do with bacteria.
What roles (other than “disease-causing”) do bacteria play in the human environment?
- Environmental applications: composting, bio-leaching of minerals, bio-remediation, sanitary landfill, sewage treatment.
- Food Production: Yogurt, cheese, Intestinal bacteria (e. coli), normal skin flora
The size of bacteria:
They’re really small:
-requires staining and really good (light) microscope lenses to see them.
The best way of telling/classifying bacteria is?
by looking at the cell wall
Stromatolites:
- Found in water or where water was
- They form when biofilms (matted together prokaryotes) collect particles over time creating rocks, trapping the bacteria from that biofilm
Cyanobacteria:
- Photosynthetic Bacteria
- Modern day bacteria similar to stromatolites
All bacteria cells have:
- Cytoplasm
- Ribosomes (smaller than Eukaryotes)
- Nucleiod (DNA one big circular piece)
- Plasma membrane
- Cell wall (NOT selectively permeable) [gram positive/negative]
Physical factors in the environment can affect the rate of reproduction of bacteria which include:
- Temperature
- Atmospheric Oxygen Level
- pH levels
- Electromagnetic radiation
How does temperature affect the rate of reproduction of bacteria?
- Psychrophile: “likes cold”
- -5 to 20 C
- Refrigeration, freezing doesn’t kill bacteria
- Mesophile:
- 20-45 C (Can be found inside us)
- Includes plant, animal pathogens (most of what we encounter falls here)
- Thermophile:
- 45C and up
- Overheating usually kills bacteria, but NOT THESE! (ex:geysers, deep sea vents)
How does Atmospheric Oxygen Level affect the rate of reproduction of bacteria?
- Aerobe: need oxygen for respiration (we fall into this) [36 ATP]
- Anaerobe: Killed in the prescence of oxygen; Fermentation produces ATP (making 2 ATP)
- Facultative: Can make ATP by respiration or fermentation (alcohol–>bacteria—>Acid—>Fungi)
- Microaerophile: “likes a little but of air”; Prefers low [O2], higher [CO2]
How does pH Levels affect the rate of reproduction of bacteria?
- Acidic: (ex; stomach ulcers)
- Neutral: (most bacteria prefer this)
- Alkaline: (ex: soil)
How does Electromagnetic Radiation affect the rate of reproduction of bacteria?
- Gamma Radiation, X-rays: Higher Penetrability; Ionizing radiation (causes formation of ions) free radicals.; Extensive cellular damage; making dark places best for bacteria!!!!
- UV radiation: Lower Penetrability —->surface sterilization; thymine dimers (causing thymine to fuse)
The only things that kills bacteria are:
- UV radiation
- Gamma Radiation
- X-Rays
Modes of nutrition for bacteria vary widely; what is Bacteria’s metabolism:
- Autotrophs
- Heterotrophs:
- Decomposers:
Autotrophs;
Makes food for themselves
Heterotrophs:
Gets food from an outside source
Relies on some other means of a food source
Decomposers:
- Special case of heterotrophs
- Breaks down dead stuff/gets its food source from it
- (digests nutrients in the compost)
Bacteria Motility: (How do bacteria get from Point A to Point B?)
- Flagella
- Axial Filaments (aka “endoflagella”)
- Gas Vesicles;
Flagella in Bacteria Motility:
In bacteria cells it rotates (instead of whipping itself further like a sperm)
Axial Filaments (aka “Endoflagella”) in Bacteria Motility:
On the inside, when rotation happens it looks like a drilling motion
Gas vesicles in Bacteria Motility:
- Found in cyanobacteria
- Can cause bacteria to float or sink by absorbing/releasing
Bacteria and its adaptations to the environment:
- Antibiotic Resistance:
- Endospore Formation
- Extracellular Secretions `
Antibiotic Resistance and Bacteria:
The bacteria can develop a resistance towards a drug, With the discovery of Penicillin it helped with this!
-Can be tested in a lab to find if it is Susceptible or Resistant
Discovery of Penicillin:
In 1928, by Alexander Fleming
- (Where mold/fungus was found, there was no bacterium—on dirty lab plates he observed it)
- Cures gonorrhea
Endospore Formation and Bacteria:
- (not in all bacteria)
- endospore: Metabolically inactive dormant structure produced by some bacteria species
- Can be detected with special staining techniques
- bacteria makes endospores when environmental conditions aren’t good.
Extracellular secretions and Bacteria:
- (slime layers, capsules, biofilms)
- [Making bacteria:]
- Mainly amino acids and sugars (very sticky)
- Protection from immune system chemicals (capsules)
- Sticky (to themselves, surfaces, host tissues
What is bioremediation?
ex: Cleaning up an oil spill from a beach using bacteria which eats oils.
What indicates Archaea to be different than other domains?
its rRNA sequence indicates differences between Archaea and other domains.
Name two major differences between Archaea and Bacteria
Archaea have no:
- peptidoglycan in cell walls
- Distinctive lipids in plasma membranes of some.
Name the four major extremeophiles:
- Extreme halophiles (likes salt)
- Extreme thermophiles (likes heat)
- Acidophillic (likes acidic conditions)
- Alkallphilic (likes basic/metal conditions)
Methanogens reduce CO2; how much methane is produced annually?
2 billion tons of methane is produce a year.
