Section2 Introduction
Isomerism
Isomers are molecules that have the same molecular formula, but have a different arrangement of the atoms in space. That excludes any different arrangements, which are simply due to the molecule rotating as a whole, or rotating about particular bonds.
Where the atoms making up the various isomers are joined up in a different order, this is known as structural isomerism. Structural isomerism is not a form of stereoisomerism.
Structural isomerism is the relation of two or more compounds, radicals, or ions that are composed of the same kinds and numbers of atoms but differ from each other in structural arrangement (as CH3OCH3 and CH3CH2OH, or in the arrangement of their atoms in space and therefore in one or more properties)
There are two types of isomerism one is structural isomerism; - where the bonds between the atoms are arranged differently. And Stereoisomerisms- where bonds are the same but the nature of bonds allows a 3-D arrangement.
Structure/function of Starch & Cellulose Structure
Glucose is used to make cellulose and starch, because starch is a polysaccharide and this is found in plants and also cellulose is founded in the plants parts, and its polymer is β- glucose molecules to form the long chains.
Starch & Cellulose Structure
Starch is a mixture of two-glucose polymers amylase and amyl pectin. The ratio of these components varies from plant to plant. The usual composition is 25% amylase but there are mutants with up to 50-70%, and naturally occurring waxy starches, which are all amylopectin. The amylase: amylopectin ration is an important determinant of starch functionality. Cellulose is very similar to amylase in many ways. It is a linear chain of 1,4 linked glucose molecules but the links are β and the chain is often much larger. The β-1, 4 links causes the chains to lie as flat ribbons rather than form helices. Cellulose chains can pack parallel to each other in tightly hydrogen-bonded crystals. (In fact, the large chains are hard to organize into crystalline layers over their whole length and instead form alternate crystalline amorphous and crystalline bands.)
Cellulose is a lot stronger than starch. Starch is practically useless as a material, but cellulose is strong enough to make fibres from, and hence rope, clothing, etc. Cellulose doesn't dissolve in water the way starch will, and doesn't break down as easily. Breaking down or dissolving in water just would be a little too inconvenient for something we use to make clothes. Not to mention, a good soaking rain would wash away all the wooden houses, park benches, and playground equipment if cellulose were soluble in water.
Starch is a long (100's) polymer of Glucose molecules, where all the sugars are oriented in the same direction. Starch is one of the primary sources of calories for us humans being.
Cellulose is a long (100's) polymer of Glucose molecules. However the orientation of the sugars is a little different. In Cellulose, every other sugar molecule is "upside-down". This small difference in structure makes a big difference in the way we use this molecule.
Difference between starch and cellulose
• Starch: 4 linkage, Spiral form; easy to hydrolyse; weak
• Cellulose: b-1, 4 linkages, Crystalline; hard to hydrolyse; strong
Optical isomerism
- Optical isomerism is a form of stereo isomerism
- The ring of carbon is basically flat with the OH and H groups either above or below the plane of the ring.
- The two forms of glucose are stereoisomers being mirror images of each other they cannot be superimposed upon each other. (See diagram below)
- In alpha glucose the OH group on Carbon 1, is below the plane of the ring (see diagram 1 below); in beta glucose the OH group on Carbon 1 is above the plane (see diagram 2).
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This type of isomerism is called optical isomerism because the two isomers rotate plane-polarised light in different directions Light is also made up of vibrations.
Introduction (Section3)
Catalyst
A substance that increases the rate of a chemical reaction, but is chemically unchanged itself at the end of the reaction. This process is known at catalysis. Catalysis works by lowering the activation energy of a reaction. The catalyst used in a reaction is written over the arrow in the equation. A catalyst, which increases the rate of one reaction, may have no effect on another.
Catalysts increase the rates of reactions by providing a new mechanism that has smaller activation energy, as shown in the diagram below. A larger proportion of the collisions that occur between reactants now have enough energy to overcome the activation energy for the reaction. As a result, the rate of reaction increases.
Activation energy is the energy barrier that must be overcome during a collision of two possible reactants in order for a reaction to occur.
Geometry is important since a head on collision would be different from a collision from the side. It is found that collisions must have a sufficient energy for a reaction to take place and this depends exponentially on an energy factor called the activation energy.
Enzymes
Enzymes are globular proteins; their molecules are round in shape. They have an area - usually of as a pocket-shaped gap in the molecule - which is called the active site.
Some enzymes are found inside cells (intracellular enzymes), and some - especially digestive enzymes - are released so they have their effects outside the cell (extra cellular enzymes) .
Only the substrate or substrates fits into the active site. There are several types of enzyme which contribute to different types of biochemical reaction - see below. It is not widely appreciated that water is also a reactant in the digestion (enzyme-controlled breakdown) of most biological molecules.
The enzyme speeds up the process of conversion of substrates (reactants) into products - usually so much that the reaction does not take place in the absence of enzyme.
Although the enzyme obviously joins with the substrate for a short while, the enzyme and substrate split apart afterwards, releasing the enzyme. Thus the enzyme is not used up in the process unlike substrates, so it can continue to react if more substrate is provided. See the diagrams below on substrates and enzymes.
Within the normal range, changes in temperature of substrate and enzyme affect the rate of reaction in accordance with predictable relations between enzyme and substrate molecules.
The effects of temperature may be explained on the basis of kinetic theory - increased temperature increases the speed of molecular movement and thus the chances of molecular collisions. Enzymes have an optimum temperature for their action.
Above normal temperatures say 60 °C, heat alters permanently the enzyme molecule. This denature is caused by heat. This change - especially in the region of the active site - mean that the enzyme is inactivated, even when returned to normal temperature.
It would be wrong to say that an enzyme is KILLED by heat, since it is only a molecule, not an organism.
The higher the temperature to which the enzyme is given and the longer the heating is continued, the more it becomes denatured and becomes less efficient.
Below normal temperatures, enzymes become less active, due to reductions in speed of molecular movement, but this is reversible, so enzymes work effectively when returned to normal temperature.
The lock and key theory
The lock and key theory is simply a way of describing how specific an enzyme is for its substrate. Just like a lock requires a specifically shaped key for it to work so does an enzyme. Each enzyme is a protein which is a polypeptide chain folded into a complex 3 dimensional structure. Part of that structure contains the active site, which is where the enzyme can bind to the substrate on which it will perform some chemical reaction. Because each enzyme performs a specific task on a specific substrate the active centre of the enzyme can be considered to be the "lock" which requires the specific "key" or substrate to perform the function. (see below for diagram on the key and lock analogy)
How the theory can be explain and how this works?
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Lock and Key analogy is the best way to explain this theory or Puzzle pieces.
- Smaller keys, larger keys, or incorrectly positioned teeth on keys (incorrectly shaped or sized substrate molecules) do not fit into the lock (enzyme). Only the correctly shaped key opens a particular lock. The characteristics of the puzzle pieces are specific, not all fit, some look similar. Enzymes are like this - hence the lock and key see next page for diagram.
- Some pieces look the same or look similar but only specific actually go together. Analogy - puzzle pieces fitting together
- There is a specific site that it fits
- A fits B, but not C, even if B and C are similar
Enzymes: Structure/shape and Function
Cells perform their functions (growth, reproduction, specific metabolic activities, etc.) by using various types of chemical reactions. These reactions must be carried out in an orderly fashion (when to begin, when to stop, rate of reaction, etc.) for a cell to function efficiently. To perform these orderly processes cells regulate chemical reactions through the use of enzymes. Enzymes are biological (protein) catalysts. Enzymes couple reactants together to form products, driving energy requiring endergonic reactions with the energy release by exeronic reactions. The three-dimensional shape of the enzyme in the diagram below shows how the substrate entering the enzyme. The shape and the structure of the enzyme allow the substrate easily to enter.
Introduction (Section4) banner
Biotechnology
Biotechnology can be defined as “using living organisms or their products for money-making purposes.” As such, biotechnology has been practiced by human society since the beginning of recorded history in such activities as baking bread, brewing alcoholic beverages, or breeding food crops or domestic animals. A narrower and more specific definition of biotechnology is “the commercial application of living organisms or their products, which involves the deliberate manipulation of their DNA molecules”. This definition implies a set of laboratory techniques developed within the last 20 years that have been responsible for the tremendous scientific and commercial interest in Biotechnology,
Biotechnology is used to Modify Plants and Animals by combining DNA from different existing organisms (plants, animals, insects, bacteria, etc.) results in modified organisms with a combination of traits from the parents. The sharing of DNA information takes place naturally through sexual reproduction and has been exploited in plant and animal breeding programs for many years. However, sexual reproduction can occur only between individuals of the same species. A Holstein cow can be mated with a Hereford bull because the two animals are different breeds of the same species, cattle. But trying to mate a cow with a horse, a different species of animal, would not be successful.
Differentiates between Traditional and modern biotechnology
Traditional biotechnology refers to a number of ancient ways of using living organisms to make new products or modify existing ones. In its broadest definition, traditional biotechnology can be traced back to human's transition from hunter-gatherer to farmer. As farmers, humans collected wild plants and cultivated them and the best yielding strains were selected for growing the following seasons.
With the domestication of animals, farmers applied the same breeding techniques to obtain desired traits among animals over generations.
In modern biotechnology, achieving desired individuality in an organism is done mostly at the gene level. Hence the gene responsible for the desired trait is identified, transferred and inserted into the organism at the cell level, to produce genetic changes. Also in other modern techniques of biotechnology such as mutagenesis, past knowledge of causes of mutations, known as mutagens, (such as exposure to radiation or temperature extremes) has been harnessed to generate intentional changes in the genetic make-up of a cell or plant tissue. For example, mutation breeding is a biotechnology technique commonly used to develop plants with novel traits. In mutation breeding, plant tissues are exposed to powerful mutagens in hopes of causing beneficial changes in the genetic make-up of the plant cells and then exposed to the conditions under which the plants would have to grow (such as pesticides, limited amounts of water and so forth). Those plants which, experienced beneficial mutations survive the exposure to the conditions and are bred and developed into plant lines.
Enzyme technology
Enzyme technology is associated with the use of enzymes as the tools of industry, agriculture and medicine. The majority of enzymes used in industrial or biotechnological applications are derived from particular fungi (Aspergillus) and bacteria. Safe organisms must be used for consumer-related uses.
Method
In the solution of bioreactor, will contain yeast Using baker's yeast (Saccharomyces cerevisiae) glucose
The bio-reactor was correctly set up ready to use by the technician. This practical did not involve any work since it was a class demo. The bio-reactor was let to work for a week with the solution which contained glucose and yeast. After the week the solution was ready to be filtered.
Inside the bioreactor the micro-organisms grown in the liquid of the glucose and their growth level can be measured, there is four phases of growth occurs in the micro-organisms.
The first is the lag phase where small growth occurs because the micro-organisms are getting used to their new surrounding. The second is exponential phase this is when the number of micro-organisms is multiply by 2 between 20-30 minutes. Then thirdly it goes into stationary phase, at this stage growth slows down and stops because of the fact that there might be a lack of food or build up of toxic waste. Lastly it goes into senescent phase at this stage the micro-organisms are vanishing because of the same reason in the stationary phase: lack of food or build up of waste. Since batch culture was used for practical 1, this means that fermentation is set up and left run for a week without adding anything to the solution.
Practical 2: Distillation of the ethanol solution
We took fermentation product from bioreactor and set up for distillation. The amount we used was 20 cm3 of fermentation product and was weighed on a digital weighing scale inside a 250ml beaker, we had to weigh the beaker first because we only wanted the weight of solution not the beaker and then subtracted the weight of beaker from the solution to get solution weight by it self, which was 18.7g of the distillate product of ethanol, but our solution was spilt a little showing that this error could effect practical a slightly.. And afterward the weight of solution was recorded.
Distillation was set as in the diagram below:
After the distillation we collected 4.6g of distilled product
We worked out the percentage yield to be:
% yield = actual yield x 100
Predicted yield
% yield = 4.60 x 100 = 24.6%
18.7
Practical 3: Oxidation of ethanol to ethanoic acid
We poured into a pear-shaped flask 10 cm3 of 1 M sulphuric acid. After added 5g sodium dichromate (VI) using a funnel, and 3 drops of anti-bumping granules. We swirled the flask gently until all the sodium dichromate was dissolved. We then very slowly of a lot of care added 2 cm3 of concentrated sulphuric acid with a funnel opening the tap gently drop by drop. The flask with solution was cooled under a cold tap water this is because the sulphuric acid we added earlier on made the solution gain heat. Now we were ready to set up for reflux, the apparatus was set up as shown below.
1 cm3 of ethanol (CH3COOH) was added down the condenser, once again very gently drop by drop. The ethanol solution was then boiled for 20 minutes under reflux. We could now work out the mass but we don’t know the density so we have to rearrange the formula: Density = mass, we rearrange to get Mass= density x volume volume
Practical 4: Distillation of the ethanoic acid solution
This practical was the continuation of practical 3 in the previous page, and involved distilling the mixture to obtain a reasonably pure sample of ethanoic acid.
Practical 5:
Evaluation
In this section evaluate data; in particular consider its reliability.
Must include the following to achieve the criteria:
- Comparison of results with published data (c3)
- Discussion of the accuracy and reliability of the various methods used for checking purity; do this by considering errors and comparing the results with partner and with the published data (A2)
- Discussion of the accuracy of the percentage yield determination (A2)
Comparison with industrial processes
Romford Brewery is a very large company with 600 personal; they make 250 million pounds from beer each year. They replaced their old manual system by a high tech computerised automation system. The automation made the production of beer very easy and quicker because the computers controlled everything that would normally done by hand, like the mashing process is monitored by computer which controls the temperature; the adding of the hobs which once again are computer controlled so that the beer has the right bitter favour and checked the temperature was right before adding of the hobs; the fermentation process is Romford produces 750 thousand barrels of beer a year, a barrel is equivalent 288 pints, and works out 1250 barrels per employee. All the beer made is supplied to 100s of pubs.
Advantages of automation
- Made the process more efficient.
- Saved more money and time in the long run.
- Reduced labours costs by employing less personal.
- Allows them to produce economy of scale: a continuous. process same as mass production which is cheaper than batch production that Ridley use.
- Heat exchanges save them money because the heat produce from fermentation can be used for another process.
Disadvantages of automation
- The automation cost 13 ½ million
- Romford has to still employ a lot of personal
- The system will consume large a amount electricity
Comparison of practical one with brewing
The starting material
