New Challenge Question June 2005

[Survivor39]

For those who are interested in Microbiology:

What make prokaryotes special in that they can occupy everywhere on Earth, e.g, hot spring, deep in the ocean floor, in Antarctic ice, compared to eukaryotes which can only occupy in a relatively limited environmental niche?

[xiao1985]

Originally Posted by Survivor39

For those who are interested in Microbiology:

What make prokaryotes special in that they can occupy everywhere on Earth, e.g, hot spring, deep in the ocean floor, in Antarctic ice, compared to eukaryotes which can only occupy in a relatively limited environmental niche?

i will make an attempt *cough
yeh it's not really my work... a friend who does micr at usyd answered as following:

because procaryotes can exploit resources much better than eucaryotes... i think it was...
and it has enzyme that can chew up inorganic matters for energy

but i think it may have something to do with the less complicated raw material it requires... as it does not need the gene to code for the organelle membrane etc...

[currysauce]

Organisms such as these are referred to as extremophiles. Most extremophiles are members of the Archaea family, to the organism itself its environment is completely normal.


i don't bloody know

[Survivor39]

xiao, you are on the right track.

Look at the metabolism of prokaryotes! They can occupy both aerobic and anaerobic conditions! This can help them to survive in a variety of environment! So how do they do it?

[Survivor39]

currysauce, yes, some of their morphological structure help them to survive in extreme conditions. Some extremophiles are halophiles, thermophiles, hyperthermophiles, psychophiles etc.

[xiao1985]

Originally Posted by Survivor39

xiao, you are on the right track.

Look at the metabolism of prokaryotes! They can occupy both aerobic and anaerobic conditions! This can help them to survive in a variety of environment! So how do they do it?

enzyme that catalyses chemical reactions which produce energy needed through non-respiratory processes?! (ie do not require oxygen)?!

[Survivor39]

Originally Posted by xiao1985

enzyme that catalyses chemical reactions which produce energy needed through non-respiratory processes?! (ie do not require oxygen)?!

Half correct - the not require oxygen part.
Prokaryotes have a diversity of metabolism because they can carry out different respiratory pathways to gain engergy (ATP). A part from aerobic respiration, they could also carry out anaerobic respiration and fermentation. Although these processes yield less ATP, they allow them to survive in environment far more extensive than eukaryotes do. Anaerobic respiration works by using substrates other than oxygen as the terminal electron acceptor (note: not enzymes like you said). these substrates may include nitrate, sulfate and even Carbon dioxide! And fermentation as you know, are used by organisms such as yeasts and a variety of other bacteria. Although prokaryotes can carry out anaerobic respiration and fermentation, they prefer to use oxygen as this yield higher amount of energy. Some prkaryotes are obligatory anaerobes and will die in the prescence of oxygen.

I hope this help you to understand more about Microbiology.

[nit]

Definitely the numerous modes of nutrition - chemoautotrophy(bacteria being the only such organisms)/photoautotrophy/heterotrophy and the ability to exhibit anaerobic respiration, aerobic respiration and being facultative anaerobes contribute to this idea. However, at the same time, eukaryotes may exhibit all of these except chemoautotrophy, so I think that that ought to be the focus of the answer. This is, however, using my limited study of the topic and so possibly incorrect.

Edit: Actually, maybe this was what you referred to in speaking about the various substrates for anaerobic respiration used by prokaryotes.