Week 2 Application Questions Flashcards
- You are working with an imaginary element with the chemical symbol M. This element has 6 valence electrons in its valence shell, and needs 2 more electrons to complete its valence shell. Element M has an electronegativity of 2.7.
a) Describe two ways in which element M would be able to complete its valence shell.
b) Element M forms a covalent bond with oxygen (electronegativity = 3.5). Describe the properties of this bond.
c) Would a molecule containing the M-O bonds described above in part (b) be able to dissolve in water? Explain why or why not.
a) Gain two e- or make two bonds
b) Difference: 3.5 -2.7 = 0.8 = polar covalent
bond, O has partial neg charge, M partial pos charge
c) Yes, it can form hydrogen bonds with
water
- Examine the structure of the following molecule: (look at study guide)
a) Identify as many functional groups as possible in this chemical structure.
b) Identify as many sites as possible capable of forming hydrogen bonds.
c) Imagine that all the hydroxyl groups in this structure were replaced with methyl groups. Describe the effect this would have on the properties of this chemical, and explain why.
a) 3 Carbonyl (keto-)group, 4 hydroxyl and 1 amino groups
b) all polar sites… with an “O”. (3), the hydroxyl groups
c) Polar functional groups would be replaced with non-polar
functional groups resulting in decreased water solubility:
less opportunity for hydrogen bonding.
- As outlined in this paper, there is a lot of research happening to identify new anabolic steroids, both as a possible treatment for muscle wasting diseases and as a way to create new steroids (sometimes called designer steroids) that will be missed by drug testing in sports.
As stated in this paper, “Athletes and bodybuilders have recognized for several decades that the use of anabolic steroids can promote muscle growth and strength but it is only relatively recently that these agents are being revisited for clinical purposes. Anabolic steroids are being considered for the treatment of cachexia associated with chronic disease states, and to address loss of muscle mass in the elderly, but nevertheless their efficacy still needs to be demonstrated in terms of improved physical function and quality of life. … Anabolic steroids continue to be the most common adverse finding in sport and, although apparently rare, designer steroids have been synthesized in an attempt to circumvent the dope test.”
- A) The table below (from Kicman et al. 2008) shows some of the different versions of anabolic steroids that have been created by researchers.
Based on the material we have covered about different ways to create molecular diversity in carbon-based molecules, what are some strategies (modifications) that you think have been employed by researchers to create these new steroids?
What strategies (modifications) have not been used by the researchers?
- changing the c-chain length
- deleting functional groups
- adding functional groups
- adding double bonds
- removing double bonds
- They have not used
- B) Do you think that these steroids would be primarily hydrophobic or hydrophilic? Explain why.
How might this affect their ability to be used as a medication in humans?
They are overall more hydrophobic.
- Because they have a lot of C-H bonds, which is nonpolar.
- Also don’t see many of the structures bonding with H2O. Therefore, interacting more with other nonpolar covalent molecules.
- C) Think about what you know or may have heard about the use of anabolic steroids. You can also go to https://www.drugabuse.gov/publications/drugfacts/anabolic-steroids to read about some of the risks associated with anabolic steroid use.
If you were a researcher that was studying the use of anabolic steroids as a treatment for muscle wasting in the elderly, what affects would you hope to achieve by making chemical modifications to the basic steroid structure?
Side effects:
1. hormonal
2. infection
3. muscoskeletal
4. cardiovascular
5. psychiatric
With ‘designer’ steroids we could try to minimize side effect for patients with existing preconditions
- e.g. more hydrophobic, could be more easily stored in tissues high in fat content
- e.g. more hydrophilic, could be added to water (drink), more easily flushed out of the body
