BIOCHEMISTRY I - PLANTS

Course CodeBSC102
Fee CodeS2
Duration (approx)100 hours
QualificationStatement of Attainment

Study the Biochemistry of Plants

Chemical reactions are at the heart of everything that happens in a plant; from the germinating of seeds and the growth of tissues, to the production of flowers and fruit. Understanding these chemical reactions will help you understand how plants grow, and in turn, how to treat them.

Study: Biochemical substances and terms, carbohydrates, lipids, amino acids, proteins, metabolism, the nitrogen cycle, photosynthesis, respiration, transpiration, acidity and alkalinity, nutrition, hormones, chemical analysis and biochemical applications in industry.

A Problem Based Approach for learning in this course, makes the educational experience practical and applied, helping you to understand, absorb and retain your new knowledge.

Prerequisites: Some secondary school chemistry will be helpful but not essential to your understanding of the course.

Student Comment: 'Having not finished high school myself and never studied biochemistry my confidence is a little low but the encouragement I am receiving from Honor [tutor] is a tremendous help and making it easier for me as I go. [The course] is helping me realize what I am actually capable of and that I am smarter than I thought. Thank you for making it possible for me to study my passion while still being able to work.' Melissa Smith, Australia, Biochemistry I.

 

Lesson Structure

  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

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 formulae 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 including:
    • carbohydrates
    • proteins
    • amino acids
    • lipids
    • nucleic acids
  • Compare differences between monosaccharides and polysaccharides.
  • Differentiate between plant and animal biochemistry, with three specific examples of biochemical processes which are unique to each.
  • 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 two commercial applications for lipids for the learners chosen industry.
  • Explain two commercial applications for proteins for the learners chosen industry.
  • Explain two commercial applications for carbohydrates for the learners industry.
  • Distinguish between an enzyme and a hormone.
  • Explain how one specific enzyme functions in a living organism.
  • Explain how one specific hormone functions in a living organism.
  • Explain the relevance of hormones to the learners industry sector.
  • Explain the relevance of enzymes to the learners industry sector.
  • Explain plant inoculum in relation to nitrogen use in plants.
  • Define relevant terminology, including:
    • Nitrogen Fixation
    • Ammonification
    • Nitrification
    • Denitrification
    • Symbiotic Bacteria
  • Explain the effect on plant yield of a deficiency in available nitrogen.
  • Explain the effect on plant yield of an excess in available nitrogen.
  • Compare differences in nitrogen deficiency symptoms between monocotyledons and dicotyledons.
  • Analyse the nitrogen cycle with diagrams.
  • Explain the significance of the nitrogen cycle to plants and animals.
  • Perform an experiment comparing the growth of 4 plants grown under differing light conditions.
  • Explain differences in plants grown under different light conditions.
  • Explain the processes of photosynthesis, with diagrams.
  • Explain the importance of photosynthesis to plants.
  • List the main biochemical processes which occur during respiration in plants.
  • 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.
  • Explain differences in plant respiration, under different climatic conditions, for a specified situation.
  • Define relevant terminology, including:
    • Transpiration
    • Translocation
    • Vapour Pressure
    • Osmosis
    • Evapotranspiration
    • Assimilation
  • Explain how water is absorbed into a plant, with the aid of diagrams.
  • Explain how nutrients are absorbed into a plant, with the aid of diagrams.
  • Perform, a simple experiment, showing the movement of dyed water into, and through a plant.
  • Explain how water is moved about in a plant.
  • Explain how nutrients are moved about in a plant.
  • Explain the purpose of transpiration, in plant function.
  • Define pH terminology including; acid, alkaline, base and neutral.
  • Explain the control of acidity and alkalinity in different living organisms, using 4 specific examples, including:
    • buffers
    • chemical reactions
  • Define relevant terminology, including:
    • calibration
    • electroconductivity
    • chromatography
    • colorimeter
    • indicators
  • Compare chemical pH test kits with chemical pH meters, in terms of the following:
    • accuracy
    • ease of use
    • portability
    • speed
    • maintenance
    • calibration
    • costs
  • Explain the practical applications of various analytical techniques including:
    • chromatography (TLC, GC)
    • colorimetry
    • atomic absorption
  • Determine the value of analytical techniques used in industry including:
    • efficiency
    • accuracy
    • ease of use
  • Differentiate between chemical toxicity and tolerance.
  • Explain the implications of LD50 characteristics with five different chemical substances.
  • Explain the implications of half-life 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.
  • Explain the function and use of two different plants as medicines for humans or animals.
  • Determine three different applications for plant tissue culture.
  • Explain how soil pH affects plant nutrient availability.
  • 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.

Extract from Course Notes:

CHEMICAL NAMES
Chemical names give you an indication of the different chemical groups which make up a compound.

Ethylene is............  CH2=CH2   
 Here we have 2 carbon atoms joined by a double bond. Each carbon atom is also bound to 2 hydrogen atoms.
 (Note: This is very similar to the ethyl group; and the name is similar to ethyl)

Ethane is ............. CH3-CH3
 Here we have a single bond between 2 carbon atoms. Each carbon atom is also bonded to 3 hydrogen atoms.
 (Note: The preface "Eth" stays the same; and it also has similarities to ethyl group)

Methane is ........... CH4
 Here we have 1 carbon atom bonded to 4 hydrogen atoms.
 (Note: This is very similar to the methyl group; just one extra hydrogen atom)

ALKYL GROUPS -These are groups of continuous chain parent hydrocarbons where the normal ending "ane" is replaced with "yl" (e.g. Butyl is an alkyl group from the parent hydrocarbon butane; and methyl is an alkyl group from the parent hydrocarbon methane).

ARRANGEMENT OF ATOMS IN A COMPOUND
Two different compounds can have exactly the same number of atoms of each of their constituents, but be different compounds with different characteristics. They are different because the arrangement of the atoms is different.
A Hypothetical Example:
*If a compound has three different atoms, joined together in a straight line it might look like this:
 A. . . .B. . . .C  (NB: The dotted line represents chemical energy bonds.)

A therefore is joined to "B"; and "B" is joined to "C":
BUT "A" and "C" are not joined together in any way.

*Another compound also has one each of A, B and C atoms but in this case the arrangement is:
    .A.   Here "A" is joined to both "B" and "C"
   .   .
  .     .   "B" is joined to both "A" and "C"
 .       .
B. . . . .C  "C" is joined to both "A" and B"

ORGANIC COMPOUNDS
Organic compounds are compounds that contain carbon. In addition to carbon, nearly all organic compounds contain hydrogen, and most contain oxygen as well. The atoms of these elements are arranged in various forms to make up most of the dry weight of living organisms.

The four main types of organic compounds are carbohydrates, proteins, lipids and nucleic acids.

CARBOHYDRATES
Carbohydrates are compounds that contain carbon combined with hydrogen and oxygen. They are one of the most significant groups of organic compounds that are made (i.e. synthesised) by living systems (i.e. within the tissues of plants or animals). Carbohydrates are significant both in terms of both quantity made and the importance of their use in living organisms.

Carbohydrates are compounds which, when analysed, give empirical formulae which are multiples of the simple formula CH2O. Chemically, carbohydrates are defined as "polyhydroxy aldehydes" or "ketones". (Don't worry too much if you don't yet understand these terms.) Examples of carbohydrates include sugars, starch, glycogen, cellulose and chitin.

Carbohydrates are made or synthesised in plants by the process of photosynthesis. (This will be studied in detail later in the course.)

Types of Carbohydrate
There are three main types of carbohydrates:

Monosaccharides
These are the simplest carbohydrates. They are made up of a chain of carbon atoms to which Hydrogen and Oxygen atoms are attached in the proportion of 1 carbon atom to 2 hydrogen atoms to 1 oxygen atom (CH20). These simple sugars, under reasonably mild conditions, can be hydrolysed into smaller compounds. (Hydrolysis is the process of splitting one molecule into two by the addition of H+ and OH- ions of water.)
Glucose is a monosaccharide and is the form of sugar which is most often transported through animal systems.
A combination of glucose and fructose forms sucrose, which is the form that plants use.

Oligosaccharides
These are compound sugars which, when hydrolysed, will yeild two to six molecules. Disaccharides are therefore oligosaccharides which yield two monosaccharide molecules when they hydrolyse.

Polysaccharides
These are made up of monosaccharides linked together in long chains. They yield a large number of monosaccharides when they hydrolyse.
Starch, which is made of many glucose molecules, is the main storage form of sugar in plants. (Glycogen is the common storage form of sugar in animals.) They must be hydrolysed before they can be used as energy sources for living systems.

PROTEINS
These are complex compounds made up of a number of amino acids. A single protein molecule can contain hundreds of thousands of amino acids joined by peptide links into one or more very long chains. There are 20 different types of amino acids which can be found in these chains. All types are found in animals; but there are fewer types found in plants.

Amino Acids
These are organic compounds which contain both the amino group (i.e. NH2) and the carboxyl group (i.e. COOH). Note: the carboxyl group is acidic.
Different species of organisms have the need for "specific" essential amino acids. Humans require the following 8 specific types of amino acids: valine, leucine, phenylalanine, tryptophane, lysine, isoleucine, methionine and threonine.

LIPIDS
Lipids are fats and oils. They should not be confused with petroleum or mineral oils.
They are insoluble in water, but are very soluble in organic substances such as ether or hot alcohol. The term lipid doesn't refer to a structural characteristic of these compounds - it refers to behavioural characteristics. The structural characteristics of lipids are extremely variable.
Fats are solid or semi solid at room temperature, while oils are liquid.
Lipids occur in both plants and animals, and are among other things, used to store chemical energy. In plants, the seeds and fruits in particular are used to store fats (oils).

Lipids are divided into the following types:

a. Neutral Lipids  
b. Phosphatides and Sphingolipids
c. Glycolipids   
d. Terpenoids eg. Carotenoids and steroids.

NUCLEIC ACIDS
Nucleic acids are the chemicals which make up genetic material in a living cell. There are two types of nucleic acids: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
DNA molecules store the genetic information. RNA molecules translate and transmit this genetic information.
DNA molecules (like proteins) are very long (ie. polymers). The molecular weight of a DNA molecule can be about 100 million. Different DNA molecules are similar, but still different to each other. A DNA molecule can self duplicate itself: this characteristic being the basis for reproduction of an offspring which shares characteristics with its parent.

 

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