CERTIFICATE IN APPLIED BIOCHEMISTRY

Learn how to Apply a Knowledge of Biochemistry to Growing and Managing Plants

Plants are constantly changing,

Cells die and new ones form. Chemicals are absorbed into the plant tissue, then undergo chemical reactions (ie. metabolic reactions), and become incorporated into the plant tissues. Components that are not needed are expelled from the plant's tissue. All of these processes are complex, but they are affected and controlled by conditions within and around the plant.

When you study biochemistry, you begin to gain insights into these various processes, and you will develop a steadily increasing understanding of how to influence the metabolic reactions in plants. In doing so, your ability to manage plant growth will itself grow.

Modules

Note that each module in the CERTIFICATE IN APPLIED BIOCHEMISTRY is a short course in its own right, and may be studied separately.

LEARN HOW NITROGEN FIXATION AND OTHER PROCESSES WORK

The biochemistry of nitrogen fixation

Amino acids are precursors for many nitrogen containing molecules such as nucleotides.   Nitrogen is a feature of all amino acids. However despite it atmospheric abundance, it is not readily useable.  N2 is relatively inert and it’s conversion into usable nitrogen compounds depends upon a few varieties of bacteria called diazatrophs.   The availability of usable nitrogen in the forms of ammonia, nitrite and nitrate is considered to be a major limiter of biological growth.

Diazatrophs include organisms such as cyanobacteria and those that inhabit root nodules in legumous plants.   Nitrogen fixation occurring in plant roots of the pea family (including beans, clover, alfalfa etc), is the product of a symbiotic relationship between the plant and the bacteria of the genus Rhizobium.   
 
Here N2 is converted to NH3 which can be incorporated into either glutamate or glutamine using glutamate dehydrogenase or glutamine synthetase respectively.

N₂ + 8H⁺ + 8e^- + 16ATP + 16 H₂0 --> 2NH₃ + H₂ + 16 ADP + 16Pi

This reaction is catalyzed by the enzyme nitrogenase.  This enzyme has two proteins: Fe-protein; MoFe-protein.  When the N2 is bound to the nitrogenase, the Fe-protein is reduced by electrons donated by ferredoxin.  The reduced protein then binds with 2 ATP and reduces the MoFe^-protein, after 8 turns of this cycle, it is then able to donate electrons to N₂ hence producing HN=NH.  This cycle is repeated twice more.  In the first repeat, HN=NH is reduced to H₂N-NH₂; this is further reduced to 2NH₃ on the second run. 

Note that in reality often the ATP expenditure can reach as high as 20 – 30 per N₂. 

Some plants and fungi as well as bacteria can also reduce nitrate (NO₃ ^-) found in soils and water.  The nitrate is reduced to NH₃ in a two step process.  In the first step nitrate is reduced to nitrite by the nitrate reductase.  The nitrite is then further reduced in the second reaction to ammonia again by nitrate reductase.

NO₃^- +  2H⁺ +  2e^- -->  NO₂ ^- +  H₂0

NO₂ ^- +  8H+ +  8e- -->  NH₄⁺ +  2H₂0

WHO CAN BENEFIT FROM THIS COURSE?

Anyone who works with plants, from gardeners and horticulturists to farmers, teachers and plant scientists can all benefit from a broader and deeper knowledge of plant chemistry.

Some who undertake this course may already be working with plants and others won't. Some will use this course for professional development; and others as a way of advancing their career or business prospects.