Mannose is a naturally occurring sugar that is important to human metabolism. Mannose can exist in an open chain form (D‑mannose) or can cyclize to form a cyclic structure (α-D‑mannopyranose). Answer the questions below about D‑mannose and α-D‑mannopyranose. Which of the Fischer projections (A-F) below represent D‑mannose? [Fischer]  Which of the chair conformations (T-Z) below represent the MOST stable conformation of α-D‑mannopyranose? [chair1] Which of the chair conformations (T-Z) below represent the LEAST stable conformation of α-D‑mannopyranose? [chair2] How many total possible stereoisomers are there for α-D‑mannopyranose (including the one drawn)? [stereopyr] How many diastereomers are possible for D-mannose? [diasman] The anomeric center of a cyclic sugar is the newly formed chiral center resulting from the cyclization reaction. Which of the carbon atoms labeled 1-6 above is the anomeric center? [anomeric] Identify ONE chair conformation (T-Z) that represents the enantiomer of α-D‑mannopyranose. [enantiomer] What is the relationship between the Fischer projections labeled B and D? [relationship]

Mannose is a naturally occurring sugar that is important to human metabolism. Mannose can exist in an open chain form (D‑mannose) or can cyclize to form a cyclic structure (β-D‑mannopyranose). Answer the questions below about D‑mannose and β-D‑mannopyranose. Which of the Fischer projections (A-F) below represent D‑mannose? [Fischer] Which of the chair conformations (T-Z) below represent the MOST stable conformation of β-D‑mannopyranose? [chair1] Which of the chair conformations (T-Z) below represent the LEAST stable conformation of β-D‑mannopyranose? [chair2] How many total possible stereoisomers are there for β-D‑mannopyranose (including the one drawn)? [stereopyr] How many diastereomers are possible for D-mannose? [diasman] The anomeric center of a cyclic sugar is the newly formed chiral center resulting from the cyclization reaction. Which of the carbon atoms labeled 1-6 above is the anomeric center? [anomeric] Identify ONE chair conformation (T-Z) that represents the enantiomer of β-D‑mannopyranose. [enantiomer] What is the relationship between the Fischer projections labeled A and F? [relationship]

Diagnosis and Treatment Upon receiving the information from Luke’s spinal tap, the presence of ameba-like organisms in his CSF was confirmed. He was immediately started on IV therapy with antiprotozoal, antifungal, and antibiotic solutions, including amphotericin B, fluconazole, rifampin, and azithromycin. Dexamethazone was also used in an attempt to counteract the ongoing brain inflammation. Sadly, despite treatment, Luke died within 10 days of returning from his trip.  Question: Luke was most likely infected with which of the following organisms? 

Five (5) of the six (6) molecules shown below have something on common with respect to their stereochemistry. Select the one that is different.

Determine the absolute configuration (R/S) of the chiral centers or E/Z configuration of the alkenes indicated below (A-D). A: [configA] B: [configB] C: [configC] D: [configD]

Five (5) of the six (6) molecules shown below have something on common with respect to their stereochemistry. Select the one that is different.  

Trehalulose (shown below) is a sugar found in small amounts in honey. Answer the questions below about the structure of trehalulose. Which two (2) chair structures below represent the chair conformations of the six-membered ring of trehalulose? Enter your choices in alphabetical order: [chair1] and [chair2]. Which of the chair structures represents the enantiomer of the six-membered ring of trehalulose? [enant] What is the absolute configuration (R or S) of the chiral center indicated with an asterisk (*)? [RSconfig] 

Consider the hydrochlorination reaction shown below and answer the questions that follow. In this reaction, a “MAJOR PRODUCT” is formed, i.e. a product that is formed in preference to the other. Assuming that the major product is derived from the most stable possible carbocation intermediate, which of the following molecules (A-F) would be the MAJOR product? [major] A “MINOR PRODUCT” is also possible in this reaction, i.e. any possible product that is not the major product. Which of the following molecules (A-F) would be the MINOR product? [minor] Considering only the major product, how many stereoisomers are possible for this molecule? [stereomajor] Considering only the minor product, how many stereoisomers are possible for this molecule? [stereominor]

Select all molecules below that are optically active.  

Identify the isomeric relationship for each pair of molecules (A-D) below. Choose the most specific answer that you can in each case.