The following questions provide problem-solving scenarios that focus on either carbohydrate, protein or lipid metabolism. You are required to answer in detail, as outlined in the Task-specific guidelines, using clear and concise, scientific English. References are included to assist with your research and writing in scientific English your writing style and research technique. Please read and follow the Marking guide carefully to understand the assessment criteria, and ask your Lecturer, Online Tutor or Librarian if you have further queries.

TASK:

Choose one (1) topic from the following list:

1. In the last few decades, the prevalence of obesity and metabolic syndrome has risen dramatically on a global scale, which has been suggested to correlate with the increased intake of added sugar and/or the large-scale consumption of "junk food". As a student of Chemistry and Biochemistry you have been asked to explain to an anxious parent why their teenage son is at risk of developing type 2 diabetes and even cardiovascular disease (stroke or heart disease) later in life. John (the son) consumes a large amount of fried chips with every meal and weighs 40 kg more than the recommended weight for his age. To track how John metabolises carbohydrate, he has been given an isotope labelled carbohydrate meal. The isotope allows the carbohydrate to be tracked after entering the mouth, with the breakdown products eventually being absorbed into the blood, just as a non-labelled carbohydrate would be.

Include in your analysis the processes involved in the digestion and absorption (into the blood) that allow energy to be extracted from the carbohydrate.

I. Explain the pathways involved in carbohydrate metabolism following a meal.

II. Briefly describe the link between diabetes and obesity, and explain why is John at risk of developing type 2 diabetes by referring to the pathways explained in I above.

III. Explain how some trace amounts of the carbon from the meal end up in John's adipose (fat) tissue.

2. A six-week-old baby was taken into intensive care. Pathology results showed the baby was suffering from Hyperammonemia. As a student of Biochemistry use your knowledge to explain the possible causes of the baby's condition to the anxious parents. Support your explanation by referring to the milk protein diet of the baby particularly focusing on the digestive processes that break down protein into individual amino acids and the metabolic processes required to maintain nitrogen balance within the body (removal of nitrogen waste from the cells).

I. Explain the metabolic pathways in amino acid metabolism and nitrogen waste removal from the cells following a protein-rich meal such as milk.

II. Briefly describe Hyperammonemia and comment on why the baby has high levels of ammonia in the blood.

III. Explain why some trace amounts of nitrogen (from amino acids) from the meal ended up in the baby's urine.

3. Humans require approximately 2000 kcal per day. For an untreated diabetic with no access to insulin, whose body is dependent on triglycerides, outline how the energy in triglycerides becomes available to the patient. Specifically, describe the diet, digestion and absorption and degradation pathways that create energy and ketone bodies.

I. Explain the metabolic pathways in which lipid metabolism leads to energy and low level ketone body production in the cells, following a triglyceride-rich meal.

II. Briefly describe how and why untreated diabetics are at risk of poor health outcomes (e.g. diabetic ketoacidosis) after excessive catabolism of lipids.

III. Explain why untreated diabetics have an insufficient oxaloacetate supply, which is needed to derive energy from lipids.