This is a draft cheat sheet. It is a work in progress and is not finished yet.
Kingdom/Domain System Evolution
1. 2 Kingdoms |
- Plants
- Animals |
2. 5 Kingdom System |
- Manera
- Plant
- Animal
- Fungi
- Protists
wrong bbecause this is saying that all the differences are equal, which is false because they evolved at different times |
3. 3 Domain System |
Current System. Domains are more broad than kingdom |
Bacteria V. Archaea
Archaea = Hottest places on earth |
Archaea cell membrane
- Formed by phospholipid bilayer |
Hydrocarbon chains can be linked so their lipids can be a monolayer. Makes membrane more stable/loss fluid. Helps retain integrity |
Bacterial Peptidoglycan
Carbohydrate chains cross linked with amino acids |
- Plant cell walls are made of cellulose in strands |
- Cellulose doesn't contain the cross linked amino acids that connect the chains (PLANTS = cellulose) |
Cross link= very strong substance. need this because bacteria is single celled |
What Unites Prokaryotes
All are conditional with known exceptions |
Unicellularity: almost always single-celled |
Cell size: mostly very small |
Chromosomes: typically have a single circular chromosome, genetical material can be exchanged via HGT |
Cell division: mainly occurs by binary fission, no mechanism for sexual reproduction (asexual reproduction) |
Internal compartmentation: no true membrane bound organelles |
Flagella: simple structure allows only for simple mechanism |
Metabolic diversity: can be capable of metabolic feats requiring remarkable chemistry |
Gram Stain- Often first step in treatment
- Gram-stains are still ofte the first figure in clinical articles about pathogens |
How does genetic diversity arise?
Examples of Horizontal Gene Transfer |
Conjugation |
Transduction |
1. One strand of F+ cell plasmid DNA breaks at arrowhead |
1. Phage infects bacterial donor cell with A+ and B+ alleles |
2. Broken strand peels off and enters F- Cell |
2. Phage DNA is replicated and proteins synthesized |
3. Donor and recipient cells synthesize complementary DNA strands |
3. Fragment of DNA with A+ allele is packaged within a phage capsid |
4. Recipient cell is now a recombinant F+ cell |
4. Phage with A+ allele infects bacterial recipient cell |
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5. Incorporation of phage DNA creates recombinant with genotype A+B |
Chromosomes are mostly sincle celled and horizontal transfer can be given to anyone in the same environment |
Pili merge and join cytoplasm |
plasmids: where antibiotic genes are held |
Virus serving as a boat for exchange of genetic material |
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Cellular Life
Unicellular |
- Most of earths organisms in history |
Multicellular |
- Fungi, Plants, Animals |
Domains
Archaea are more closely related to eukarya than bacteria |
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Bacteria |
Archaea |
Eukarya |
Nuclear Envelope |
Absent |
Absent |
Present |
Membrane-enclosed Organelles |
Absent |
Absent |
Present |
Peptidoglycan in Cell Walls |
Present |
Absent |
Absent |
Membrane Lipids |
Unbranched Hydrocarbons |
Some branced hydrocarbons |
Unbranched hydrocarbons |
HNA Polymerase |
One kind |
several kinds |
several kinds |
Initiator amino acid for protein synthesis |
Formyl-methionine |
Methionine |
Methionine |
Introns in genes |
Very rare |
present in some genes |
present in many genes |
Responsible to the antibiotics streptomycin and chloramphomicol |
Growth usually inhibited |
Growth not inhibited |
Growth not inhibited |
Histones associated with DNA |
Absent |
Present in some species |
Present |
Circular Chromosome |
Present |
Present |
Absent |
Growth at temperatures >100C |
No |
Some Species |
No |
Archea membrane lipids can form monomers |
Introns show more complex genetically |
Histones allow packaging of DNA. No histones means doesn't have to be as compacted |
Internal Membrane or Organelles?
Some internal membranes are complex invaginations of the Plasma Membrane |
Aerobic Prokaryote |
Photosynthetic Prokaryote |
Respiratory membrane |
Thylakoid Membrane |
Cyanobacteria--> started O2 release |
Metabolic Diversity of Prokaryotes
Carbon Source |
Energy Source |
A. Autotrophs
B. Heterotrophs |
A.Phototrophs
B.Chemotrophs
--Organic (Chemoorganotrophs)
--Inorganic (Chemolithotrophs) |
Prokaryotic metabolism varies with respect to O2 |
Obligate aerobes require O2 for cellular respiration |
Obligate anaerobes are poisoned by O2 and use fermentation or anaerobic respiration, in which substances other than O2 act as electron acceptors |
Facultatice anaerobes use O2 if it is available, but can survive without it |
Nitrogen Metabolism |
Prokaryotes ungergo NITROGEN FIXATION |
Additional Points |
1. Source of Carbon: biomolecules have carbon skeletons
-Where does the organism get the carbon atom from?
--heterotrophs: Organic molecules |
2. Aquire energy to arrange carbon atoms
-phototrophs=sun
-Chemotrophs=organic |
Oxygen has nothing to do with this at this time |
Phacaltative: can survive with or without O2 |
Nitrogen Metabolism:Need nitrogen!
-can only get it from other molecules |
only thing that can break the triple bond of nitrogen is prokaryotes. N2= most on earth |
-not found purely in the environment. "chillin with other species" |
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Domains
Bacteria - prokaryotic |
most abundant organisms on earth. Highly diverse and poorly understood. |
Archaea - prokaryotic |
But different from bacteria. Very poorly understood |
Each domain is monophyletic |
Monophyletic |
Contain all decendents of common ancestor |
First Cellular Life Form Appearance
3.9 Billion Years Ago |
For 3.9 Billion Years life has been evolving to the present life forms |
- Humans organise life by phylogeny |
Closest # = least # of nucleotide differences |
more differences in sequence, the longer the time difference |
Interesting Facts
It is estimated that only 1-10% of bacteria species are know |
We think that maybe 1% of archaea species are known |
Why are so few prokaryotic species known? |
We dont know more about bacteria because they have just been studied by growing them in a lab. |
Most bacteria metabolisms are so complex they cant figure out how to get them to grow on their own, in a lab |
Cell walls are found in which of the following domains? |
Bacteria, Archaea, Eukarya |
- Cell walls in all domains (cell walls are made of peptidoglycans) |
Prokaryotic Shape
There is no correlation between prokaryotic cell shape and gram-stain or other test |
Bacillus: 0.5um |
Coccus: 2um
strep |
Spirillum: 3um
lyme disease |
There is no correlation between prokaryotic cell shape and gram-stain or other test |
Bacterial Cell Wall
Bacteria can be classified by their cell wall |
Gram (+) |
Gram (-) |
- Teichoic acid only in G+ |
- LPS major endotoxin |
- Lipoteichoic Acid (LTA) |
Thin peptidoglycan and outer/inner membrane |
peptidoglycan very thick and only one membrane |
- Outer lipid--> LPS
one of the major endotoxins that causes the body to get sick |
Cell wall of bacteria=traditional classification |
Gram stains change approach to treatment |
The Gram Stain-Identifies Bacterial Category |
1. Bacteria are stained with crystal violet
all cells are stained purple |
2. Iodine stabilizes the crystal violet with the cellular material |
3. Alcohol may extract the crystal violet from the cell
The stain complex is removed from the gram-negative cells (makes them white/clear) and remains in the gram-positive cells (stays purple) |
4. Bacteria are stained with safanin
Gram-negative cells are stained pink; gram ppositive cells are still purple |
All microbes can be stained in this way. But with cells in the Domain Bacteria (only), the staining makes predictions about envelope structure.
cell wall and membranes |
Other Notes |
Alcohol breaks down membrane and wash out iodine
- + doesn't allow this to happen |
This procedure only works for bacteria |
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