Sugar, Insulin, Obesity and Cancer

Task One [Monday Feb 17th]: Insulin Production:

• Draw and annotate a pancreatic cell with all the structures and their functions for the production and export of proteins - specifically insulin. 

• Draw a cartoon image of insulin and.... Describe the different levels of protein structure and the forces at each level that maintain its share.

Task Two [Wednesday Feb 19th]: Insulin Physiology 

• Describe the normal cycle for insulin: stimulus, production cell, target cell, response, feedback.
• Increase in level of glucose in blood leads to production of insulin in beta islets of pancreas
• Insulin targets muscle (use glucose for ATP production), fat (energy storage), liver cells (glycogenesis)
• This results in decrease of blood sugar levels in which less insulin is produced (negative feedback)

• Distinguish between the storage of glucose in liver/skeletal muscle from storage in white adipose tissue [a connective tissue]
• Liver/skeletal muscle: glucose to glycogen (glycogenesis)/glucose to ATP (metabolized)
• Adipose tissue: glucose to fats

• Distinguish between the three cases: normal insulin response, diabetes type 1 and diabetes type 2. 
• Normal insulin response: Insulin produced in beta islets, and binds to receptors of membranes on the target cells
• Diabetes Type 1: cells body attack islet cells, inhibiting production of insulin
• Diabetes Type 2: diet related, leading to receptors to be less receptive/sensitive to insulin

Task Three [Friday February 21st]: Response to Insulin - Cell Level

From the above quotes and reviewing the content of the core please answer the following questions:

• Describe the target cell response mechanism in liver, skeletal and adipose tissues by:

• Draw and describe the fluid mosaic model of the cell membrane

• Predict  the transport mechanism liver, skeletal and adipose tissues would use to absorb [uptake] glucose from the blood.
• Active transport using a protein membrane due to large size of glucose

• Compare and contrast the predicted mechanism to the actual process used by intestinal epithelium to absorb glucose from the intestinal lumen. 
• The mechanisms are similar in the intestinal epithelium (use GLUT2 as well)

Task Four [Tuesday, February 25th]: Response to Insulin - Gene Level

• Explain the cancer cell dependency for glucose [energy and lipids]. There are two pieces of the mystery eluded to above: 

• One: Mitosis- cancer cells use glucose and glycogen for mitosis and growth

• Two: Lipids- cancer cells use fat tissues to synthesize its own membrane

Cancer cells response to glucose requires more protein transporters in the cell membrane and more enzymes for glucose metabolism for mitosis, lipid synthesis and nucleotide synthesis. 

• Describe the entire process of gene transcription, mRNA production, [include splicing to remove introns], translation by ribosomes. 
• Gene transcription: RNA polymerase binds to promotor on DNA strand, unwinds strand, and uses one strand of the double helix as template for replication
• mRNA production: RNA nucleotides brought by RNA polymerase, producing RNA strand; before leaving nucleus for ribosome, introns are cut out by spliceosomes in which a cap is added to one end and adenine tail is added to the other
• Translation by ribosomes: Ribosomes bind to start codon of mRNA, which is followed by tRNA binding to the mRNA via the ribosome (tRNA is bound to amino acid); continuation of this leads to an amino acid chain. tRNA binds to mRNA in A site of ribosome, and is then moved to P site, which leads to another tRNA to bind to A site, forming peptide bond between amino acids of the two tRNAs, tRNA in P site is released in E site without amino acid.

Task Five [Thursday, February 27th]: Glucose metabolism

• State and draw a basic cartoon of stages of glucose metabolism used to generate ATP in the non-proliferative tissues. [In class we broke the entire process into five steps]

• Describe the input and output with regards to: NAD+, NADH+H, CO2, ATP, H2O

• Distinguish between animal use of lactate fermentation and alcoholic fermentation by bacteria and yeast. 
• Yeast produces carbon dioxide and ethanol
• Animals produce lactic acid

• Explain the advantage of cells switching to anaerobic metabolism [fermentation] of sugars.
•  Anaerobic metabolism of sugars offers energy quicker because the process is faster

• Distinguish between catabolic and anabolic reactions and the role of NAD+ and NADP+ in catabolism and anabolism.
• Catabolic reaction: break down of molecules, giving out energy
• Anabolic reaction: formation of molecules using energy; uses both NAD+ and NADP+