Blog

In the lactate dehydrogenase active site shown, which residue or molecule serves as the general acid–base that protonates/deprotonates the substrate during the pyruvate ⇄ lactate conversion?

Information for Questions 16-18 (7 points) Hyaluronic acid is an example of a glycosaminoglycan and functions as the major component of synovial fluid (it lubricates the joints) and the vitreous humor of the eye. It is also available as a dietary supplement, skincare product, and can be used to treat osteoarthritis as an injectable. Image Description Hyaluronic acid is a long glycosaminoglycan composed of repeating disaccharide units. Both sugars in the disaccharide dimer are modified glucose units. The first (leftmost) glucose in each disaccharide dimer has, attached to carbon 5, a carboxyl group in place of the typical hydroxymethyl group. The second (rightmost) glucose in each disaccharide dimer has, attached to carbon 2, an NH group followed by an acetyl. The two glucose units within each disaccharide are attached to each other via a glycosidic linkage that, on the first (left) glucose, connects to carbon 1 in the up position, and on the second (right) glucose, connects to carbon 3 in the up position. Two different disaccharide units attach to each other in sequence via a glycosidic linkage that, on the second (right) glucose of one disaccharide unit, connects to carbon 1 in the up position, and on the first (left) glucose of the next disaccharide unit, connects to carbon 4 in the down position.

Upload an image of your answer to this question at the end of the exam. Sketch and label a Lineweaver-Burke plot of initial velocity, Vo, vs. [S] for the enzyme glucokinase relative to the enzyme hexokinase. Note: This is a relative plot (not exact) to show the difference in activity of the two enzymes compared to each other. Assume that both enzymes have similar values.

3-deoxy-L-Glucosamine, in Fischer representation. 

Kelly tries to remember the word ‘a cow’ but instead says ‘a moo’. This is an example of ________________ in language. 

Which pair correctly gives BOTH linkages in hyaluronate (first→second, then second→next)? 

  The act of bringing the vocal folds together is called

Upload an image of your answers to this question at the end of the exam. This is from the Wikipedia article on the glycoprotein Muc1. (Mucin-1. (2019, December 8). In Wikipedia.) “Mucin 1, cell surface associated (MUC1) or polymorphic epithelial mucin (PEM) is a mucin encoded by the MUC1 gene in humans. MUC1 is a glycoprotein with extensive O-linked glycosylation of its extracellular domain. Mucins line the apical surface of epithelial cells in the lungs, stomach, intestines, eyes, and several other organs. Mucins protect the body from infection by pathogen binding to oligosaccharides in the extracellular domain, preventing the pathogen from reaching the cell surface. Overexpression of MUC1 is often associated with colon, breast, ovarian, lung, and pancreatic cancers.” O-linked glycoproteins have a polysaccharide structure attached to an R-group of a Thr or Ser on the protein portion of the glycoprotein through an O-

In lactate dehydrogenase, replacing Arg171 with Lys drops enzymatic activity to ~0.05% of wild type. Which explanation best accounts for this dramatic loss? 

Discussion 4: Your text mentions the high failure rate for condoms (close to 20%), what should they have included in this statistic?