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/