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In addition to these macronutrients, prokaryotes require various metallic elements in small amounts. These are referred to as micronutrients or trace elements. For example, iron is necessary for the function of the cytochromes involved in electron-transport reactions. Some prokaryotes require other elements—such as boron (B), chromium (Cr), and manganese (Mn)—primarily as enzyme cofactors.

The ways in which prokaryotes obtain energy

Prokaryotes can use different sources of energy to assemble macromolecules from smaller molecules. Phototrophs (or phototrophic organisms) obtain their energy from sunlight. Chemotrophs (or chemosynthetic organisms) obtain their energy from chemical compounds. Chemotrophs that can use organic compounds as energy sources are called chemoorganotrophs. Those that can also use inorganic compounds as energy sources are called chemolitotrophs.

The ways in which prokaryotes obtain carbon

Prokaryotes not only can use different sources of energy but also different sources of carbon compounds. Recall that organisms that are able to fix inorganic carbon are called autotrophs. Autotrophic prokaryotes synthesize organic molecules from carbon dioxide. In contrast, heterotrophic prokaryotes obtain carbon from organic compounds. To make the picture more complex, the terms that describe how prokaryotes obtain energy and carbon can be combined. Thus, photoautotrophs use energy from sunlight, and carbon from carbon dioxide and water, whereas chemoheterotrophs obtain energy and carbon from an organic chemical source. Chemolitoautotrophs obtain their energy from inorganic compounds, and they build their complex molecules from carbon dioxide. The table below ( [link] ) summarizes carbon and energy sources in prokaryotes.

Carbon and Energy Sources in Prokaryotes
Energy Sources Carbon Sources
Light Chemicals Carbon dioxide Organic compounds
Phototrophs Chemotrophs Autotrophs Heterotrophs
Organic chemicals Inorganic chemicals
Chemo-organotrophs Chemolithotrophs

Role of prokaryotes in ecosystems

Prokaryotes are ubiquitous: There is no niche or ecosystem in which they are not present. Prokaryotes play many roles in the environments they occupy. The roles they play in the carbon and nitrogen cycles are vital to life on Earth.

Prokaryotes and the carbon cycle

Carbon is one of the most important macronutrients, and prokaryotes play an important role in the carbon cycle ( [link] ). Carbon is cycled through Earth’s major reservoirs: land, the atmosphere, aquatic environments, sediments and rocks, and biomass. The movement of carbon is via carbon dioxide, which is removed from the atmosphere by land plants and marine prokaryotes, and is returned to the atmosphere via the respiration of chemoorganotrophic organisms, including prokaryotes, fungi, and animals. Although the largest carbon reservoir in terrestrial ecosystems is in rocks and sediments, that carbon is not readily available.

A large amount of available carbon is found in land plants. Plants, which are producers, use carbon dioxide from the air to synthesize carbon compounds. Related to this, one very significant source of carbon compounds is humus, which is a mixture of organic materials from dead plants and prokaryotes that have resisted decomposition. Consumers such as animals use organic compounds generated by producers and release carbon dioxide to the atmosphere. Then, bacteria and fungi, collectively called decomposers , carry out the breakdown (decomposition) of plants and animals and their organic compounds. The most important contributor of carbon dioxide to the atmosphere is microbial decomposition of dead material (dead animals, plants, and humus) that undergo respiration.

Questions & Answers

What is Staining?
Fazal Reply
what is biology
Biology is the study of life
what is biology
Ysabella Reply
biology is a study of living things
Biology is a diverse branch of science that deals with mostly living things
What happen when inhibit the transcription?
what is the effect of not doing sexual intercourse
what is the mechanism of cellular respiration
Rita Reply
what is enzyme
garry Reply
They are organic catalysts that alter the rate of chemical reactions in the body.
meaning they speed up reaction
Enzymes are forms of chemicals that are specialized in their own areas.(eg digestion of food)
what is a cell
Praize Reply
Basic Functional Unit of Life
what is biology
Mordi Reply
biology is the study of living organisms and their interactions with one another and their environments
which of the following event does not occur during some stages of interface?
Bangha Reply
What is microfilaments
KHalid Reply
What is multicellular organisms
Ovie Reply
these are organisms with more than two cells
the process when a male toad fertilizer a female eggs is called what?
Ahrebe Reply
how did unicellular organisms form plants and animals or is it that different unicellular organisms formed plants and animald
YXNG Reply
name the components of faeces
undigested carbohydrate, fibre
what are unicellular organisms..?
they have only one cell
faeces contains many undigested food materials, after the food has been digested then it will be absorbed in the blood stream for assimilation.,......... but the remains toxic materials are stored in the rectum these toxic materials are the faeces and it contains bile salts, the polysaccharides .
unicellular organisms are the ones with only single cell.
thanks for your answers guys.
what is class bryophyta
Emefa Reply
how many stages do we have in glycolysis?
10 stages
the presence of a membrane enclosed nuclosed is a characteristics of what
Addai Reply
eukaryotic cell

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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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