prokaryotes by aram gebretensae and quddus akinlusi
TRANSCRIPT
Prokaryotes
By Aram Gebretensae and Quddus Akinlusi
Some facts and basics
Prokaryotes…-Have a biomass 10x of eukaryotes-Are widespread due to quick adaption-Multi diverse group-Classified as two domains, Achaea and Bacteria (differ in structural, physical, and biochemical character)
What’s the difference?!
Function, Structure, and genetic adaptive style
• Most are unicellular• Cells range from 1-5micrometer smaller than
eukaryotic cells• Most common shapes, rods(bacilli), spheres
(cocci), spiral.
Cell-surface structure, why is it important
• Determines how potent the prokaryote is• Gives guidelines as to how scientist should
develop an antibiotic if such prokaryote is said to the harmful
Da Cell Wall
• Main component• Maintains shape and prevent lyse• Under salty conditions bacteria can’t grow (food
preservation)• Made of peptidoglycan, a network of modified-
sugar polymers cross linked by short peptides.
Gram Staining
• Develop by Danish physician Hans Christian Gram• Used for virus identification.• Gram positive have more peptidoglycan• Gram negative have less peptidoglycan and is
more complex• Gram negs are more dangerous
world application
• Needed to check potency of bacteria• Anti-peptidoglycan drugs are made to treat the
disease• EX. Penicillin
Cell defense and movement
• Cell all covered by capsule or fimbriae
- serves as a key so bacteria could bind to cells.
- shields bacteria from immune system attacks
Cell moves through series of chains flagellins called a flagellum
Motility
• Definition: ability to spontaneously and actively move
• Almost all prokaryotes are capable of this• In a heterozygous environment , they exhibit
taxis, movement towards or away from a stimulus
• Most common is chemo taxis (chemo-chemical, taxis-order
Internal and genomic organization
• Much simpler genome• Has about 1/1000 of eukaryote DNA with little
protein appearance• Most chromosome is in the nucleoid• Also has plasmid that has few genes • Plasmids are useful in protection against
antibiotics
Reproduction and Adaptation
• Division is through binary fission• Some reproduce in 1-3 hrs, while some create
new in 20 min• Prokaryote presence is limited b/c of nutrition
competition and digestion by other organisms.• Some can develop resistant cells called
endospore; for example the anthrax bacteria• Adapt quickly through fast reproduction that
causes increase likelihood of beneficial mutations
Nutritional and metabolic adaptations that evolved
• Four models of nutrition are
Photoautotroph: organism that obtain energy from light
Chemoautotroph: organism that obtain energy from chemical
Photoheterotroph: use light for energy but must obtain carbon organically
Chemoheterotroph: must consume both organic molecules for both light and carbon
Photoautotroph and heterotroph
organism that obtain energy from light
Nitrosomonas bacteria (Chemoautotroph )
Use energy from simply oxidation of simple inorganic compounds to make food
Anthrax(Chemoheterotrophic)
Anthrax is a gram-positive aerobic rod chemoheterotroph who is immune to phagocytosis.
Metabolic relationship to oxygen
• Metabolic depends on oxygen• Obligate aerobes use 02 for cellular respiration• Facultative anaerobes use 02 but can also grow
on fermentation• Obligate anaerobes are poisoned by 02 so some
stick to fermentation or get chemical energy through anaerobic respiration
Metabolic co-op
• Co-op between prokaryotes allows them to use environmental resources they couldn’t use as individual
• Ex, cynacobactrium anabaena has genes for both nitrogen fixation and photosynthesis but can’t do both.
• Filamentary cell carry out photosynthesis while heterocytes do nitrogen fixation
Metabolic relationship to oxygen
• Metabolic depends on oxygen• Obligate aerobes use 02 for cellular respiration• Facultative anaerobes use 02 but can also grow
on fermentation• Obligate anaerobes are poisoned by 02 so some
stick to fermentation or get chemical energy through anaerobic respiration
Molecular systemiacs
• In 1970, carl Woese and his colleagues, through prokaryotes gene sequence, found that prokaryotes, once labeled bacteria, were actually more related to eukaryotes.
• Were later placed as Archea• This changed the Phylogenic prokaryote chart
Archaea
• Share similarities between eukaryotes and bacteria• 1st Prokaryotic Achaea were extremophiles,
(lovers of extreme conditions)• Extremophile include thermophile, halophile• Methanogens use co2 to oxidize H2 to create
Methane• All extremophiles and Methanogens are members
of the clade Euryarcheota
Chemical Recycling
• Prokaryotes like Chemoheterotrophic ones function as decomposers
• Other prokaryotes like cyanobacteria convert inorganic products into forms that can be consumed by other organisms
Symbiotic relationships
• Ecological relationship between organism is called symbiosis
• Symbiont is smaller, larger is the host• 3 symbiotic relationship are commensalism, mutualism,
parasitism• Commensalism one benefit, mutualism both,
parasitism, one benefit at the expanse of the other• The well being of many eukaryotes depend on the
mutualism of prokaryotes in the body
Pathogenic prokatytes
• Cause about ½ of human diseases• Ex. Lyme disease is caused by the transmittance
spirochete Borrelia burgdorferi through ticks in deer and field mice
• Classified as exotoxins and endotoxins• Exotins are proteins secreted by these prokaryotes• Endotoxins are lippolysaccrides components that
are released when the prokaryote dies
Sources
• http://www.tutorvista.com/content/biology/biology-i/cell-structure/prokaryotic-eukaryotic-cells.php
• http://www.schmidtandclark.com/bacillus-cereus• Campbell, N. A., & Reece, J. B. (2004). Mendel and the gene idea. Benjamin
Cummings. Retrieved from http://wps.aw.com/bc_campbell_biology_7/• Moore. (n.d.). Mountain empire community college. Retrieved from
http://water.me.vccs.edu/courses/env108/lesson5b.htm • Bailey, R. (n.d.). About.com. Retrieved from
http://biology.about.com/od/cellanatomy/ss/prokaryotes.htm • Ganesh , K. (2010). Modes of nutrition in different types of plants. Retrieved from
http://www.tutorvista.com/content/biology/biology-iv/plant-nutrition/plant-nutrition-modes.php
• Symbiotic relationships. (2011, August 26). Retrieved from http://www.buzzle.com/articles/symbiotic-relationships-examples.html
• geology.com. (2011). Retrieved from http://geology.com/articles/ticks-lyme-disease/