LEARN PLANT BIOCHEMISTRY

• Learn from university trained graduates who have applied biochemical knowledge in commercial situations
• Improve your capacity to work in horticulture, gardening, forestry, pharmaceuticals, food production and other industries

Lesson Structure

There are 9 lessons in this course:

1. Introduction
2. Lipids and Proteins
3. Enzymes
4. Nitrogen and the Nitrogen Cycle
5. Photosynthesis and Respiration
6. Assimilation and Transpiration
7. Acidity and Alkalinity
8. Chemical Analysis
9. Biochemical Applications

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

• Identify characteristics of common chemical compounds important in plant biochemistry.
• Explain the characteristics of major biochemical groups including; carbohydrates, lipids and proteins.
• Explain the characteristics of chemicals which control biological processes, including enzymes and hormones.
• Identify the role of nitrogen in plant biological processes, including the nitrogen cycle.
• Identify the role of photosynthesis in biological systems.
• Explain the role of respiration in plants.
• Explain characteristics of assimilation and transpiration in plants.
• Explain the effect of acidity and alkalinity on biochemical systems.
• Develop simple chemical analysis skills relevant to testing plants and soils.
• Identify applications and uses for biochemical processes and products.

What You Will Do

• Explain the formula of ten specified, chemical compounds commonly found in plants
• Calculate the percentages of elements contained in two specified chemical compounds
• Differentiate between characteristics of major groups of biochemicals
• Compare differences between monosaccharides and polysaccharides
• Differentiate between a fat and an oil
• Explain the characteristics of a specified protein formula
• Compare two fibrous proteins with two globular proteins
• Explain the functions of carbohydrates in plants
• Explain how one specific enzyme functions in a living organism
• Explain how one specific hormone functions in a living organism
• Compare differences in nitrogen deficiency symptoms in monocotyledons and dicotyledons
• Analyse the nitrogen cycle with diagrams
• Perform an experiment comparing the growth of 4 plants grown under differing light conditions
• Explain the processes of photosynthesis, with diagrams
• Identify the differences between anaerobic and aerobic respiration
• Explain glycolysis, including the sequence of chemical reactions which take place
• Explain the Krebs cycle, including the sequence of chemical reactions involved.
• Compare respiration in a plant with respiration in an animal
• Perform, a simple experiment, showing the movement of dyed water into and through a plant
• Explain how nutrients are moved about in a plant
• Define pH terminology including; acid, alkaline, base and neutral
• Explain plant responses to changes in soil pH
• Analyse the effects of three different fertilizers on the pH of growing media.
• Explain the effects of abnormal pH levels in a specific case study of a physiological process, in a living organism.
• Identify factors involved in controlling acidity and alkalinity in a specific case study.
• Differentiate between chemical toxicity and tolerance.
• Explain the implications of LD50 characteristics with five different chemical substances.
• List the active toxins in ten poisonous plants which commonly occur in your home locality.
• Explain the effects of two naturally occurring toxins on the human body.
• Determine three different applications for plant tissue culture.

Who is this course for?

Anyone who works with plants will benefit by knowing more about the chemical processes that are constantly underway inside a plant. This makes this course relevant to gardeners, farmers, nurserymen, foresters, greenkeepers and even people who harvest, market or use plants as food crops.

You don't need to be a chemist to be applying a knowledge of plant chemistry in your daily work. This is NOT a course designed to train you to be a chemist! Chemists require far more than a single 100 hour course like this.

This will however give you a fundamental understanding of the chemistry of plants; an understanding that can be invaluable to anyone who works with plants; from gardeners and foresters, to farmers and laboratory assistants. If you want to go deeper into biochemistry, this course is a great starting point that can be followed with our Biochemistry II and III courses.

The PURPOSE of this course is to allow you to appreciate the application of biochemistry to your area of applied science, and to use biochemical applications and services in a very practical way in your study area.

You do not require a strong background in chemistry to be able to do this course; though chemistry to the level of at least year 11 will be a distinct advantage in at least parts of the following studies.

What chemicals occur in plants?

Thousands of different chemicals can be found in plants; but not all in all plants. You can't hope to understand them all from one short course, but you can begin to understand the fundamentals and some of the more important groups such as alkaloids.

Alkaloids

• Alkaloids are nitrogen containing compounds which are extracted from plants by use of an acid solution. The word alkaloid simply means, like an alkali.
• Alkaloids are made in plants from amino acids, and are found mainly in leaves, seeds and roots.
• Alkaloids are important because they tend to have significant affects on animals. Most herbal medicines are rich in alkaloids. The active constituents (ie the poisonous parts) of poisonous plants are also alkaloids.
• Alkaloids normally have complicated, cyclic structures, and nitrogen is almost always located in a heterocyclic ring.

Alkaloids are classified into four main groups according to the type of heterocyclic ring system they contain:

1. Pyrrolidine Alkaloids
eg. Atropine (found in deadly nightshade) and cocaine.
2. Quinoline and Isoquinoline Alkaloids
eg. Quinine, Opium, Methadone, Codeine, Morphine, Mescaline
3. Pyridine & Piperidine Alkaloids
eg. Nicotine, Coniine (found in poison hemlock), Pyridine and Piperidine
4. Indole Alkaloids
eg. Indole Acetic acid, Tryptophan, Skatole and Indole.

POISONOUS PLANTS

There are many commonly grown plants that are quite poisonous. Some, such as Nerium oleander are quite well known as being poisonous, while others, such as Narcissus pseudonarcissus (daffodil), many people may not realise that they too, have poisonous parts. Some are poisonous to only some people, possibly causing a skin rash or some other allergic reaction in that person. In some plants, it is only a certain part of them which is poisonous, for instance rhubarb stem can be eaten, but the leaves are quite toxic (obviously it is best to know what a plant is, and what parts of it can be used, before taking it internally). This is just meant as a caution it is only a small group of plants, that even following ingestion of a small amount of material, results in serious poisoning.

Plants may be considered to be poisonous, but the actual toxicity of the plant can depend on locality, age of plant and various environmental factors.

1. Sorbus aucuparia (rowan tree) produces small scarlet fruit, which are often made into jams and jellies. In past times they were used for various remedies such as for an anti diarrhoeic and they were also used as a source of vitamin C. But on the other hand, the fresh fruits are considered to be poisonous (eating them only produces mild symptoms).

2. Tanacetum vulgare (tansy) can be used in cooking as a flavoring, or made into a tea which reputedly has medicinal properties. The younger leaves are always used, but if taken in too large a quantity, the tea can supposedly act as an irritant narcotic and therefore be quite toxic.

Many plant poisons are extremely active substances, in suitable doses they are important medicines, though in ancient times they were often used for committing murder! Some plants contain poisons that are not found in other plants. The most important plant substances that act as poisons are as follows:

3. Essential oils. They are often used as scents and as constituents of spices and medicinal herbs. Such oils are well taken up by the skin and mucous membranes and after being absorbed they act as general cell poisons. For example pulegone, the oil from Mentha pulegium (pennyroyal), can be fatal when the essential oil of the plant is misused as an abortifacient.

4. Alkaloids are basic substances, widely distributed in the plant kingdom.
There are numerous types of alkaloids, such as Pyridine/Piperidine and steroidal alkaloids.

5. Amino acids. While amino acids are essential for synthesizing body proteins, there are a large number of non protein amino acids derived from plants, and some of these have toxic properties. Some of these are responsible for poisoning grazing animals, such as indospicine, which is present in Indigofera spp.

6. Cyanogenic glycosides. These are one of the most toxic substances to man.
It occurs in the seed of some Rosaceae genera and in linseed (in the normal use of linseed as a laxative it is not toxic).

7. Cardioactive glycosides are present in a large group of plants, including Digitalis sp. (foxgloves) and Euonymus europaeus (spindlebush). These plants usually taste extremely bitter and often cause vomiting; poisoning is therefore rare.

8. Furanocoumarins can cause injury and blistering to the skin. Plant acids can be non toxic and add to the flavour of the fruit etc., though others such as oxalic acid can be toxic, disrupting the blood clotting mechanism.

9. Saponins have long been known as fish poisons. Some saponins irritate the skin and the mucous membranes, and are known to be the toxic constituents of several poisonous plants including Hedera sp. (Ivy).

As can be seen from this list, there are many substances responsible for the toxic effects of plants and caution should be taken at all times.