5. Pernicious anemia is a disease in which the intestine is unable to absorb vitamin B12, frequently due to the loss of the generically named "intrinsic factor" produced by the parietal cells of the stomach lining. Intrinsic factor is a glycoprotein that binds to vitamin B12 and is required for its uptake in the ilium. Vitamin B12 is synthesized only by microbes, and we get it either from digesting animal protein or from our commensal microbiome. Vitamin B12 is unique among metabolic cofactors in that it contains the trace element cobalt, coordinated in a corrin ring structure that is similar to the porphyrin ring system in heme. Loss of intrinsic factor, often through autoimmunity, results in the inability to absorb B12 and ultimately a loss of red blood cells that results in anemia and can be deadly (“pernicious"). VITAMIN BI2 INTRINSIC FACTOR DIETARY B12 ANTIBODIES PERNICIOUS ΑΝΑΕΜΙΑ HYDROXYCOBALAMIN ILEUM NUMBNESS (a) In pernicious anemia, N5-methyltetrahydrofolate accumulates, and cells run out of tetrahydrofolate. This results in an inability to synthesize nucleotides, preventing DNA replication and the production of red blood cells. Why does N5-methyltetrahydrofolate accumulate in the absence of vitamin B12? What other metabolites accumulate and are depleted in this pathway due to the loss of vitamin B12? (b) How might loss of vitamin B12 alter gene expression? (c) What would happen to the rate of conversion of serine to glycine in the absence of vitamin B12 and why?

14. Complete the following table: Enzyme Lipase Peptidase Where it is produced Salivary glands Pancreas Where it acts in the digestive tract Stomach Small intestines inoitasaib 163 sight w Substrate Proteins Lactose Product Maltose en Glucose

Chapter 6: PROTEINS What are the roles of proteins in the body. a) What is the basic unit of proteins? b.)What are Essential Amino Acids? c.)How many essential and how many non-essential amino acids do we have? Explain why protein formation is an all or nothing event? How are the amino acids recycled? What is protein denaturation? Is denaturation harmful or beneficial? Explain your answer a.) How proteins digested and absorbed in the body? b.) What happens to an amino acid if it consumed in large amounts? Is it all absorbed? c.) What happens to proteins once absorbed into the body’s cells? What are they initially used for? 7.) What is protein quality? Give examples of high and low quality proteins. 8.) What happens to excess amino acids? 9.) What is a limiting amino acid? Explain what happens if an amino acid is limiting. 10.) a.)Does everyone need to eat animal protein?       b.) what are some health benefits of a vegetarian diet?       c.) What are the nutrients that a commonly…

64, The following is correct regarding gastrointestinal tracts and accessory organ a, gastrointestinal tracts include the liver b, Accessor organs includes the pancreas c, both are correct d, None of the above