Biochemistry III (Plant Processes)

Course CodeBSC302
Fee CodeS3
Duration (approx)100 hours
QualificationStatement of Attainment

Deepen your knowledge of Plant Biochemistry

This course develops a deeper understanding of how plants grow, and in doing so, has valuable and practical benefits for horticulturists, farmers, plant scientists or anyone involved in growing plants.

Lessons cover: glycolysis, electron transport, oxidative  phosphorylation, carbohydrate metabolism, lipid metabolism, photosynthesis, nucleotide metabolism, enzymes, reproductive processes, hormones and more.

Prerequisite: Biochemistry I and II or equivalent knowledge.

Lesson Structure

There are 11 lessons in this course:

  1. Introduction
  2. Glycolysis
  3. Movement Through Membranes
  4. Electron Transport and Oxidative Phosphorylation
  5. Sugar and Polysaccharide Metabolism
  6. Lipid Metabolism
  7. Photosynthesis
  8. Nucleotide Metabolism
  9. Enzyme Activity
  10. Reproductive Processes in Plants
  11. Other Processes

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.

Aims

  • Explain the interaction between the various biochemical processes within the plant cell
  • Explain the process of glycolysis.
  • Describe the transport mechanism of bio-chemicals through plant membranes.
  • Explain the processes of electron transfer and oxidative phosphorylation, and their importance to energy regulation in plants.
  • Explain the structure and metabolism of carbohydrates
  • Explain the metabolism of lipids.
  • Explain the processes of photosynthesis and the role of the light and dark reactions of photosynthesis in the growth of plants.
  • Explain biochemical nucleotide metabolism.
  • Explain enzyme reactions and catalysis in biochemistry.
  • Explain metabolic processes relevant to reproduction in plants.
  • Explain other biochemical processes including biochemical communication through hormones.

Learn about Plant Biochemicals and What Happens to them in the Plant

Inside any plant, a chemical factory is constantly at work; making different types of chemicals, then changing those chemicals into others.

 

Consider Lipids

Lipids are biological compounds containing carbon, hydrogen, oxygen and other elements such as nitrogen and phosphorous. Lipids include fats and oils. Fats are solid or semi solid at room temperature, while oils are liquid. The structural characteristics of lipids are extremely variable. Insoluble in water, they form the basis of cell membranes and also function as stores of chemical energy. 

Lipids are fatty acids and their derivatives, and substances related biosynthetically or functionally to these compounds.

Fatty Acids are compounds synthesised in nature via condensation of malonyl coenzyme A units by a fatty acid synthase complex. They usually contain even numbers of carbon atoms in straight chains (commonly C14 to C24), and may be saturated or unsaturated, and can contain a variety of substituent groups.

There are two major types of lipid – simple and complex. Simple lipids may in fact be formed from complex polymers, and include carotenes, sterols, and xanthophylls. Complex lipids are those that convert to soap after alkaline hydrolysis and include acylglycerols, waxes and phosphoglycerides.  

There are a number of different lipids that are important to plant growth. Phosphoglycerides act as structural components in the membranes of cells and cellular organelles. Triacylglycerols function as energy storage in organs such as fruit and seeds. Waxes and cutin, present in the cuticle, are also lipids, providing a protective external layer for leaves and other organs.      The storage for carbon of lipids in seeds and fruit has extremely important economic implications.  The majority of the world’s edible and industrial oils are derived from seed and fruit based lipids.

Plant lipids are among the most prolific on earth, and the majority of animal life is dependent upon these as a source of essential fatty acids and energy.  The biosynthesis of lipids in higher plants is similar to that of mammals but there are differences.  Primarily fatty acid fatty acid synthesis only takes place within the plastids unlike mammals & bacterial where it occurs in the cytosol.  This is important as it then requires that the fatty acids are distributed to other organelles.  Another significant difference is that plant cell walls are primarily composed of galactolipids as opposed to phospholipids in animals & bacterial.

 

Fatty Acid Biosynthesis by Plastids

Fatty acid biosynthesis is not a direct reversal of the beta oxidative pathway, but rather the biosynthesis occurs through the condensation of carbon units which is the reverse of the beta oxidation.  All carbon atoms found in a fatty acid have been taken from reserves of CoA (Acetyle Coenzyme A) found with in plastid.   In this process, eight two carbon fragments are used to form a 16 carbon saturated fatty acid, Palmitate.  Palmitate may then be further changed to form other saturated fatty acids.  This may occur by either desaturation (shorter chains) or elongation (longer chains).

In biosynthesis Acetyl CoA is only the precursor of the methyl end of the fat chain, the carbons come via malonyl CoA after it has modified the Acetyl part of the Acetyl CoA into an appropriate substrate.  Malonyl CoA has no other metabolic role than as a precursor for fatty acid biosynthesis and the required co-factors come from the chloroplast membranes in green plants and in seeds.    

Acetyl CoA & Malonyl CoA condense and give off Co2 & one CoA, resulting in butyryl-ACP which has had two extra CH2 groups added.  This is why fatty acids always have an even number of carbons.  All reaction from this point onwards involves ACP. This process repeats itself until there are 16 or 18 carbon atoms.     

Approximately 75% of the fatty acids produced in plants are unsaturated.   Double bonds are introduced by enzymes such as stearolyl-ACP desaturase, a unique enzyme in that is a soluble enzyme, all others in plants are membrane proteins.

 

Just a Glimpse

This is just a tiny example of what goes on inside plants, and the type of insight you will build throughout this course.

No one course will ever teach you all of the processes that happen inside a plant. There are many things we don't even know, but as human research progresses, we do discover more every year.

This Course Can Enable You to Understand
By undertaking this course, your ability to find information about plant biochemical processes will grow. You will be able to better understand what you encounter and better apply it in dealing with plant management in the real world.

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