Essay Example on Saccharomyces cerevisiae or Baker's yeast








Saccharomyces cerevisiae or Baker's yeast is a single celled organism which contains a collection of different enzymes and in this experiment catalase will be the one to be explored Catalase is an enzyme made of amino acids that catalyse the breakdown of hydrogen peroxide H_2 O_2 to oxygen and water It is tetrahedrally arranged all of which contain an active site which contains a NADPH and a heme group These active sites match the ones of hydrogen peroxide and therefore cause bonds to break and new ones to form hence giving us the products of oxygen and water This shows we can efficiently measure the breakdown of hydrogen peroxide using catalase as an enzyme due to its structure The baker's yeast is being used to convert hydrogen peroxide to water and oxygen to demonstrate the significance and power of microorganisms in converting compounds such as H_2 O_2 Baker's yeast was chosen specifically as it is a well known member of the yeast family and is significant in biotechnological research due to its easier use than well isolated enzymes In the commercial industry yeast costs significantly less due to the fact it is a unicellular organism and has a large variety of enzymes available Therefore being eukaryotic cells they contain a nucleus which makes them more complex than bacteria but are not as complex as plant cells or mammals which makes them the most suitable model to investigate multicellular organisms The overall equation for the experiment reaction is as follows 2 H_2 O_2 2 H_2 O O_2 This shows that for every two hydrogen peroxide molecules that are broken down the enzyme gains two water molecules and one oxygen molecule

When broken down the amount of oxygen released or produced is can show how rapid or slow the enzyme activity of the catalase is Moreover an enzyme is a biological molecule that speeds up the rate of a reaction They contain an active site to which a substrate molecule binds This is known as the lock and key as only a specific substrate can bind to a certain enzyme's active site Likewise the catalase present in the yeast will act as an enzyme to catalyse the breakdown of hydrogen peroxide into oxygen and water As enzymes are proteins the structure of them and their active site can be changed by other factors such as temperature The dependent variable in this experiment will be the volume of oxygen collected and the independent variable will be the temperature of the hydrogen peroxide and yeast solution as it will be varied to determine whether it affects the volume of oxygen gas produced using yeast as a catalyst There are also a number of factors that will be controlled in order to obtain the most accurate results possible Firstly the volume of hydrogen peroxide solution will need to be kept constant by using 4 cm 3 of 3 hydrogen peroxide solution so that the final volume of oxygen produced does not vary This leads onto my second control to ensure the volume of the yeast suspension will be kept constant at 2 cm 3 for the same reason To ensure no excess oxygen gas is collected the time period allowed to collect the results must be kept constant at 120 seconds

This will be done by starting the stopwatch immediately after the hydrogen peroxide has been poured into the yeast suspension and then stopping it as soon as the allocated time is reached Furthermore the temperature for each run will have to be maintained for 120 seconds to ensure the maximum volume of oxygen gas is produced for that certain temperature This will be done by ensuring that the solution will be kept in the water bath with a thermometer placed inside Finally the yeast will have to be from the same brand and batch as different yeast brand and batches have differing levels of activity and this would alter the results and make them inaccurate Therefore this experiment will be used to determine the effectiveness of yeast as a catalyst in different temperatures to see which one produces the maximum volume of oxygen during the decomposition of hydrogen peroxide The interest of this research question stemmed from my interest in a profession in the medical background In our medical society in school we were required to research articles of interest and then discuss them together as a group Whilst doing this I came across an article that stated catalase reduces peroxide in our bodies and therefore pain This linked to a disease known as Hashimoto s when your own immune system attacks your thyroid which produces the body's hormones It stated that if a person with Hashimoto s was given a high dosage of iodine there would be bad side effects one of which include excessive production of peroxide hence it is mandatory for them to control these peroxide levels as it is toxic in vast amounts As the thyroid already requires peroxide to produce thyroid peroxidase TPO large build ups of this are counteracted by the enzyme catalase As the human body has an average temperature of 37 it intrigued me to find out if this was the most effective temperature for catalase to breakdown the peroxide Hence different temperatures will be tested to see if they affect the production of oxygen gas during the breakdown of hydrogen peroxide using catalase in yeast as catalyst

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