Bacteria and Archaea
Cell wall prevents spontaneous combustion of cell in hypotonic environment
In hypertonic water environments they oftenlose water and shrink away from their wall.)Hydrolyze
Bacterial cell walls made up of peptidoglycan-a polymer composed of modified sugar cross linked by short polypeptides
Gram Stain-technique used to categorize biological species according to differences in cell wall composition. Done by first staining with crystal violet dye and iodine, then rinsed in alcohol, then stained with red dye like safranin that enters the cell and binds to its DNA,
Gram Positive- bacteria with relatively simple walls composed of a thick layer of peptidoglycan
Gram negative- bacteria containing a cell wall with less peptidoglycan and are structurally more complex, containing a outer membrane that contains -lipposaccharides(carbohydrates bonded to lipids)
peptidoglycan- A polymer that makes up bacterial cell wall composed of modified sugars cross linked by short polypeptides.
Originally prokaryotes which all life on earth share as a common ancestor. Bacteria were originally single celled organisms that entered wounds of other living things eventually devleloping further through evolution to affect specific species.
Prokaryotes lack a nucleus with their their chromosome is located in the nucleoid A region of cytoplasm not enclosed by a membrane. they have have a cell wall composed of a layer of polysaccharide or protein in what is known as a capsule
Bacteria develop resistant cells called endospores which is used when the bacteria does not have water or essential nutrition. It replicates the viruses chromosome and surrounds it with a multilayered structure where it remains dormant until conditions can support it.
Some prokaryotes stick to their substrate or to one another by means of hairlike appendages called fimbriae
Taxis-directed movement toward or away from a stimulus
Pili-appendages that pull two cells together prior to DNA transfer from one cell to the other
flagella-scattered over the entire surface of the cell or concentrated at one or both ends.
Eukaryotes-cell with a membrane enclosed nucleus and membrane enclosed organelles. Organisms with these cells are called eukaryotes
Plasmids- small rings of independently replicating DNA molecules called plasmids
The genetic diversity of prokaryotes is a result of rapid reproduction, mutation and genetic recombination
A prokaryotes constant reproduction leads to increased mutations which is similar to evolution allowing different variations of a bacteria to combat against immune systems
Their are also more chances for prokaryotes to mutate due to its constant genetic recombination
genetic recombination-combining of DNA from two sources into a single zygote.
The three opportunities for the prokaryote to mutate are transformation,transduction and conjugation
Transformation-Genotype and possibly the phenotype of a prokaryotic cell are altered by the uptale of foreign DNA from its surroundings
movement of genes from one organism to another is called horizontal gene transfer
A regular cell can pick up viral cells DNA through replacing the allele for pathogenticity with the viral alelle.
The cell is now known as a recombinant because it contains DNA derived from different cells
Transduction-when Phages(the viruses that infect bacteria) carry prokaryotic genes from one host cell to another.
Viruses cant replicate by itself because lack of genetic material but can inject DNA into Prokaryotic chromosome.
Conjugation-DNA transfered between two prokaryotic cells when temporarily joined together through a pillus, always a one way transfer
F factor- A plasmid or the piece of DNA in a chromosome that allows a cell to form pili and donate DNA during conjugation
cells lacking f factor-F^- cells with the f factor-F^+
Bacteria can gain a resistance to specific antibiotics by stopping the antibiotic from reaching the targeted protein or changing the protein itself stopping its effectiveness. Bacteria can also create resistance genes against specific vaccines
These resistance genes are often carried by plasmids called R plasmids
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Nutritional and metabolic adaptations
Prokaryotes who can metabolize oxygen are known as obligate aerobes
Obligate anaerobes-prokaryotes who oxygen is toxic too
anaerobic respiration-a organism that does fermentation. Breathes through inorganic materials that aren't oxygen such as nitrate ions(NO3^-) or sulfate ions (SO44^2-)
Facultative anaerobes- canbreathe using oxygen but can also use other ions if oxygen isn't present
Nitrogen fixation-when cyanobacteria and methanogens convert nitrogen(N2) into ammonia(NH3) which is then used to make amino acids and other organic molecules
Metabolic cooperation-prokaryotic cells work together to share environmental resources they could not use as individual cells
heterocysts- cells in a filament which carry out nitrogen fixation. Produces nitrogen for neighboring cells and receives carbohydrates in return.
Biofilms- surface coating colonies on prokaryotic species. Allows entry and exit of nutrients and waste
Major groups of bacteria
Proteobacteria-gram negative, uses all forms of trophs to produce energy. Split among five subgroups-alpha. beta, gamma, delta, epsilon
Alpha proteobacteria- closely related to eukaryotic hosts. Often used by genetic engineers to carry foreign DNA into the genomes of crop plants. Some say these evolved from Aerobic alpha proteobacteria to mitochondra through endosymbiosis
endosymbiosis- relationship between two species in which one organism lives inside the cells of another
Beta Proteobacteria- nutritionally diverse subgroups that contains Nitrosomnas, a genus of so)il bacteria that is involved in nitrogen recycling by oxidizing ammonium(NH4^+)
Gamma Proteobacteria-autotrophic members that include sulfur bacteria. oxidyzing H2S and creating sulfate as a waste product.
Delta Proteobacteria- subgroupd including slime secreting myxobacteria- bacteria that occur when soil dries out or food is scarce congregating into a fruiting body which release myxospores that find more suitable colonies.
Epsilon Proteobacteria- most species in this subgroup are pathogenic to human and other animals
Chlamydias- parasites that can only survive within animal cells, depending on host for resources like ATP. The cell walls are gram negative but contain no peptidoglycan.
Spirochetes-helical gram negative heterotrophs spiral through their environment by means of rotating flagellum like filaments.
Cyanobacteria-gram negative photoautotroph. only prokaryotes with plant like photosynthesis. components of many phytoplankton
Gram-Positive bacteria-commonly help decompose the organic matter in the soil. Lack cell walls and tiniest of all cells
Archaea
extremophiles- archaea that live in environments so extreme that few other organisms can survive there
Extreme Halophiles-live in highly saline environments
Extreme thermophiles- Archaea that thrive in hot environments where their DNA and proteins do not dismantle at high temps
Methanogens-archaea that release methane as a by product of their unique ways of obtaining energy
Prokaryotes role in the biosphere
Chemical recycling-the recycling of chemical elements between the living and nonliving components in a ecosystem.
Prokaryotes assist this process as decomposers cells that break down dead organisms and waste products to reproduce natural resources
Prokaryotes are involved in many forms of ecological interactions
symbiosis- ecological relationship in which two species live in close contact with eachother.
Host- larger organism in a symbiotic relationship
Symbiont- smaller organism in a symbiotic relationship
Mutualism-ecological interaction between a prokaryote and its host in which both organisms benefit.
Commensalism- a ecological relationship in which one species benefits while the other is not harmed or benefitted.
Parasitism- ecological relationship in which a parasite eats the host cells contents, tissues or body fluids
Parasites that call disease are called pathogens
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Pathogenic bacteria uusually get us sick by producing toxins.
Exotoxins-proteins secreted by certain bacteria and other organisms
Endotoxins-lipolysaccharide components of the outer membrane of gram negative bacteria, Only release bacteria when the bacteria die and cell walls break down