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Introduction to Enzymes

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Enzymes These are biological catalysts, speeding up reactions within living organisms. Each enzyme is specific to a certain reaction. The enzymes do not change during a reaction and can be used again and again. They are involved in building large molecules from smaller ones (eg protein synthesis ie growth), changing molecules from one type to another and breaking large molecules into smaller ones ( eg digestion ie fats into fatty acids and glycerol.) Enzyme structure Enzymes are long protein molecules coiled into very specific shapes and held in place by forces along parts of the molecule. A part of the enzyme molecule will consist of a dent or hole (the active site) Chemical reactions Each of our cells needs hundreds of chemical reactions to happen quickly and efficiently. For a chemical reaction to take place the reacting particles have to collide with enough energy to react (activation energy) Reactions are more likely to happen if- 1. The number of collisions increases 2. The energy of the collisions increases 3. ...read more.


Aerobic respiration Aerobic respiration is a very important enzyme controlled chemical reaction that occurs in all living cells. It gives us energy allowing our cells to do all the processes needed for live eg 1. Energy for life processes 2. Energy for building (synthesis) and breaking down (digestion) of molecules 3. Energy for muscle contraction 4. Generating body heat in mammals and birds Glucose + Oxygen carbon dioxide + Water + Energy . It breaks down glucose from our food (brought to the cells by the blood), by reacting it with oxygen (from the lungs brought to the cells by the blood) and produces carbon dioxide a waste gas (which is removed in the blood and taken to the lungs to be exhaled), water (which is also removed by the blood as a waste product) and energy used by the cells. Respiration occurs in mitochondria (small rod shaped organelles within cells) The more energy a cell needs the more mitochondria the cell will have, eg muscle cells will have many, fat cells will have very few. ...read more.


New proteins are made from amino acids in organelles called ribosomes. Enzyme uses Enzymes Enzyme Use Protease Washing powder (breaks down stains from protein) Lipases Baby foods (pre-digest proteins to digestion easier) Carbohydrases Washing powders (breaks down stains from lipids) Isomerase-converts glucose into the sweeter sugar fructose( for the slimming industry) Using Enzymes Advantage Disadvantage Can work at low temperature (cheaper) Sensitive to temperature Can work at low pressure (cheaper) Sensitive to pH Can be obtained from microbes (cheap) Need to be supplied with nutrients and oxygen and have waste products removed This topic lends itself well to data interpretation questions. The data could be presented in a table, graph or description of an investigation such as a clinical trial. You need to remember the basics. Enzymes are proteins; they become denatured at high temperature or as pH moves from the optimum. The rate of reaction will depend on other factors such as concentration of enzyme or substrate. In clinical trials cost may be an issue as well as safety. You should consider if the data provided comes from an independent source or could it be biased. Was the sample size big enough to maker the results reliable. ...read more.

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The candidate gives a fairly in depth response, they explain what enzymes are, how they work and they give examples to why they are useful. Furthermore, they have used appropriate terms throughout their work which indicates they have a good ...

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Response to the question

The candidate gives a fairly in depth response, they explain what enzymes are, how they work and they give examples to why they are useful. Furthermore, they have used appropriate terms throughout their work which indicates they have a good understanding of this topic. In addition to this, the candidates introduction starts well, it is always a good idea to give a brief description of your topic. However, the candidate does not state what they plan to discuss, this is something you should do as it allows the reader to clearly see the purpose of your essay from offset.

Level of analysis

The candidate has taken the time to link together other topics within biology which demonstrates a wider range of knowledge, this is a useful skill, one in which can help your studies. However, I feel that the candidates use of tables to display information is unhelpful, it detracts from the essay. At this the level of qualification you should be able to write scientific information in continual prose. In addition to this the candidate could have received a higher grade had they demonstrated that they had taken the time to research this subject. By doing background research and including information within your essay that is above and beyond your specification, you show that you are able to learn independently. Furthermore the extra information you include in your work can make your essay more interesting to read. Though you must remember to write a bibliography and site any resources you use, which includes providing links to webpages. This is important as it shows the steps you have taken to prepare your work and providing you write up information in your own word it prevents you being accused of plagiarism. On a final note, there is no conclusion for this piece of work which is a mistake, it is important to write a conclusion as this gives you a chance to leave the reader with a good impression of your work. You should end your essay by writing a summary of your key points with reference to why these are important as this helps to tie together any loose ends and bring your essay to a close. You should also give a personal response to your topic, for this type of essay that could simply be what you have learnt from writing this piece of work.

Quality of writing

There are no issues with spelling or grammar throughout this essay, though I would like to add, that if you use ‘e.g’ or ‘i.e’ you must put a full stop between the letters, which is the something that the candidate hasn’t done.

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