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Describe how the Organelles in the Beta Cells Work Together to Produce and Secrete Insulin

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´╗┐Describe how the Organelles in the Beta Cells Work Together to Produce and Secrete Insulin The hormone insulin is produced by the beta cells in the pancreas. Beta cells are located in the pancreas in clusters known as the islets of Langerhans. Insulin is vital in the body to lower blood glucose levels. Although it does not directly decrease glucose levels in the blood, it stimulates the muscle and liver cells to store excess glucose. The production and secretion of the protein insulin requires certain substances to be brought in to and taken out of the cell and also involves many organelles. The process begins in the nucleus where the DNA (deoxyribonucleic acid) molecules can be found. DNA is folded and coiled into chromosomes in the nucleolus. This is surrounded by a double membrane which has pores in it. Genes are sections of DNA which contain instructions on how to make proteins; however, the DNA molecule is too large to get through the pores in the membrane so a section is copied into RNA (ribonucleic acid). This is called transcription. The RNA then leaves the nucleus and joins with a ribosome in the cytoplasm where it can be used to synthesise a protein. The messenger RNA is 'read' by the ribosome. ...read more.


However, 8 out of the 20 essential amino acids are manufactured by cells. The basic amino acid structure is made of carbon, hydrogen, oxygen and nitrogen. Other elements could be required to make the R-group. If these elements are non-polar, they are transported by diffusion in to the cell. If they are large and/or polar, they are transported by facilitated diffusion, using protein channels or pumps in the case of sodium/potassium. Insulin is made of 2 polypeptide chains joined by bonding between zinc ions in the R-groups of amino acids. To manufacture these in the cell, zinc ions would be transported in by protein channels, using facilitated diffusion, as they are polar. Once in the blood the insulin is carried to all areas of the body where it binds to glycoprotein receptors in the cell membranes of its target cells. Insulin stops the use of fat as an energy source by inhibiting the release of glucagon. Insulin is secreted in to the blood in a constant proportion to remove excess glucose from the blood, which otherwise would be toxic as it affects the osmotic potential of the blood. Experiment on affect of temperature on enzyme activity. Temperature (ºc) Number of bubbles in 5 minutes Test 1 Number of bubbles in 5 minutes Test 2 Number of bubbles in 5 minutes Test 3 Average number of bubbles ...read more.


To improve this, it could be repeated with the following changes: Firstly, different potatoes may have different amounts of catalase in them, especially if they are different ages. To avoid this affecting the investigation all the potato samples should be cut from the same potato, from the middle, and be freshly cut just before they are used. This would ensure that the amount of catalase available is constant for each test tube. Secondly, the bubbles could be different sizes therefore counting bubbles in an imprecise way of measuring the rate of reaction. The oxygen could be collected in a measuring cylinder that is full of water as it would displace the water. This would give a quantitative value that is more accurate that counting bubbles. Using bungs and delivery tubes also does not give the most precise results as oxygen could escape into the atmosphere and therefore not be measured. The apparatus should be sealed with petroleum jelly to reduce the loss of oxygen. Enzyme action is greatly affected by changes in pH. Altering the pH of an enzymes environment (away from its optimum pH) will affect the bonding pattern of the tertiary structure of the enzyme, therefore changing the active site shape, temporarily denaturing the enzyme. As pH could change when hydrogen peroxide is broken down, a buffer solution should also be added to prevent this from happening. This would maintain the pH and therefore denaturing would not occur. ...read more.

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