Bacteria and Archaea
In this chapter you, the reader, are going to be learning about the single-celled organisms called archaea and bacteria. What's so important about microscopic little specs you may ask? Well you're about to find out sooner than you know...


CONCEPT 27.1






Prokaryotes have been going under natural selection under a LOT of different environment conditions. Even though they are unicellular, most of the time they are found to be in colonies. They range from a size of 0.5-5microns; while regular eukaryotic cells range from 10-100microns. (The only exception with the prokaryotes is the giant prokaryote, which range in usually a whopping 750microns!)

Structure and functions

There are three diffrent body types for a prokaryote:
  • The Cocci, which is a spherical cell that are just about always in pairs (diplococci);
  • The Bacilli, which is a rod-shaped cell, are most of the time solitary but do come in forms of chains
  • The Spiral, ...It's just a spiral... But travels in a corkscrew rotation:)

Cell Surface Structure

Prokaryotic cells, just like any other cell, need to protect themselves from turning into a hypotonic or hypertonic state. They do this with their peptidoglycan cell walls. There are two kinds of prokaryotic cell body work. There's Gram-positive and Gram-negative. These two are determined using a technique called Gram staining. The difference between positive and negative is their cell layers.Positive cells have a really thick peptodoglycan layer and negative have both an outer and inner membrane with the peptidoglycan in between. So in gram staining the negative cells are pinkish while the positive are just really dark in color. Some prokaryotes are covered by a capsule that protects them from an immune system, stick to other cells and form colonies, and/or protect from dehydration. Fimbriae are lil fiber like hairs in which some species that contain them cause gonorhea. There's also another appengae that looks alike but it's a sex-pilus. This sex pili brings together two cells and the one with the pilus will donate its DNA to the recipient.

external image BacterialSex.gifThis be 2 prokaryotic cells; one with the fertility gene which is the sex pilus and it donates its DNA to the recipient.
external image 300px-Gram-Cell-wall.svg.png

Motility


Cells use this little thing called a Flagellum to maneuver around its environment. Some species can travel FIFTY times the body length in a single second. The prokaryotes use this system called Taxis.
There are two types of reactions when "driving" Taxis style: positive chemotaxis, which means The cell is moving towards a positive material (food, oxygen, ect.); and negative chemotaxis, this means the cell is running away from anything that will cause them any type of harm (toxins, predators, ect.)

CONCEPT 27.2

Internal and genomic organization


Endospores are sort of like the hardcore, rugged form of an original cell. Sort of like if you think the endospore as the the seed of a fruit encased in a super protective case until conditions for living are good again. Prokaryotic cells lack the membrane-bound nucleus of a eukaryotic cell but, instead they have circular, ring-shaped chromosomes located in the nucleoid . In addition there are also these smaller things like the ring-shaped chromosomes called plasmids. Because of the difference between the prokaryotic and eukaryotic proteins and RNA content, certain anti-biotics can be used to kill off prokaryotes if they are a danger to the human body,

external image 27_08ProkChromosome.jpg

Transformation and transduction

 Here are some vocab words you need to know before watching the videos.



Transformation: http://www.youtube.com/watch?v=MRBdbKFisgI

Transduction: There wasnt a video on transduction but, basically what it is: a virus infects a bacterial disease and that virus phage babies consumes the gene from the bacterial cell, then once all the phages are done with the prokaryote, that one that took in the certain gene for say the fertilization gene, injects its phage DNA into a new bacteria and then in recombines with the new DNA.

Conjugation: http://www.youtube.com/watch?v=O-EdX4MaMFE

CONCEPT 27.3



Diverse nutritional and metabolic adaptionshave evolved in prokaryotes


Prokaryotes are catorgorized by what they eat.
  • Photoautotroph: photosynthetic organisms that use synthesis to intake carbon.
  • Chemoautothroph: Just like the photoautotroph, but rather than photosynthesis, uses inorganic compounds like Carbon Dioxide, to oxidize inorganic substances.
  • Photoheterotroph: Obtain energy from the sun, but gathers carbon in only it's organic form.
  • Chemoheterotroph: must consume organic molecules to obtian both energy and carbon.

Nitrogen fixation: Nitrogen cells can be used to fix amino acids or other organic molecules.



Vocabulary.


  1. Peptidoglycan: A network of modified-sugar polymers cross-linked by short polypeptides.
  2. Gram stain: Classify bacterial diseases into two groups.
  3. Gram-positive: Simpler and large amount of peptidoglycan.
  4. Gram-negative: Less peptodoglycan, are structually more complex.
  5. Capsule: A sticky layer of polysaccharide or protein.
  6. Fimbriae: Used to stick to other individuals in a colony.
  7. Sex pili: Appendages that pull two cells together prior to DNA transfer from one cell to the other.
  8. Taxis: Movement towards or away a stimulus.
  9. Nucleoid: A region of cytoplasm that appears lighter than the surrounding cytoplasm in electron micrographs.
  10. Plasmids: Smaller rings replicating its own DNA.
  11. Endospore: The protective seed.
  12. Transformation: the genotype and possibly the phenotype of a prokaryotic cell are altered by updates in a foreign DNA.
  13. Transduction: Bacteriophages, phage virus that infect bacteria, carry bacterial genes from one cell to another one.
  14. Conjugation: Genetic material is transferred between two same species, bacterial cells that are temporarily joined.
  15. F-factor: Fertility factor.
  16. F-plasmid: The key to the DNA donors.
  17. R-plasmid: Resistance factor.
  18. Obligate aerobes: Cellular respiration and can't live without air.
  19. Obligate anaerobes:Poisoned by air.
  20. Anaerobic resperation: accept electrons, other than oxygen gas.
  21. Faculative anaerobes: Oxygen is used.
  22. Nitrogen fixation: Cells can be incorporated this fixed nitrogen into amino acis or other organic molecules.
  23. Heterocytes: Speciealized cell, to work in with the colony.
  24. Biofilms: Surface coating colonies, They grow, way bigger,
  25. extremophiles: Likes extreme environments.
  26. Halophiles: Likes extremely salty environments.
  27. Thermophiles: Likes extremely hot environments
  28. Methanogens: A group of t archeae with a unique way to take each others close off.
  29. Decomposers: Breaking down corpses ,dead vegetaion,
  30. Symbiosis:Two species living together.
  31. Host: Host gets away with death..
  32. Mutualism: both parties benefit.
  33. Commensalism: one benefits and the other is whatever.
  34. Parasitism: One party is slowly killing the other off for his benefit.
  35. Pathogen: Parasites known to cause diseases,
  36. Exotoxins:proteins secreted by certain bacteria and other organisms.
  37. Endotoxins: breaks cell walls down.