Question

1. Covalent and non-covalent bonds.
2. Hydrogen bonds: what type of interaction, which atoms are involved.
3. Covalent bonds, hydrogen bonds, Van der Waals forces, electrostatic interactions.
4. Polarity of water
5. What is the maximum number of hydrogen bonds that one water molecule can have with neighboring water molecules?
6. Hydrophobic and hydrophilic molecules.
7. Colligative properties of water
8. Osmosis: water flow
9. Isotonic, hypertonic and hypotonic cells: describe
10. Amphipathic molecules.
11. What is the molecular structure of water?
12. Water as a universal solvent
13. Define and describe cohesion and adhesion
14. Define and describe surface tension
15. How does capillary action work?
16. K_a, pK_aand pH (Definition, equations and simple problems)
17. Ionic product of water (Kw)
18. How many H+ are found in pure water
19. Weak acids and their conjugated base
20. What can you calculate with the Henderson-Hasselbalch equation
21. Titration curves
22. Buffering zone

23. TOPIC 2: AMINO ACIDS, PEPTIDES AND PROTEINS

24. Amino acid structure and classification
25. All amino acids have a chiral α-carbon EXCEPT ________
26. What type of amino acids are used during protein biosynthesis?
27. Amino acids as acids an bases
28. Amino acid titration curves, isoelectric pH.
29. Peptide bond (Draw the structure)
30. What are peptides?
31. Zwitterions

Answer 1

1. Covalent and non-covalent bonds

Covalent bonds are the bonds formed between the atoms due to mutual sharing of electron pair in the bond. Thus the electron pair in the bond belongs to both the atoms.

Non-covalent bonds are the bonds between atoms which do not form due to sharing of electrons. These include hydrogen bonding, vander waal forces of attraction, electrostatic bonds etc.

2. Hydrogen bonding.

The bonds which are formed between an electropositive hydrogen and any other electronegative atom are called as hydrogen bonds. It is an electrostatic interaction developed due to electronegativity differences between the atoms participated in hydrogen bonding.

3. Covalent bonds, hydrogen bonds, vander waal forces, electrostatic attraction.

Covalent and hydrogen bonds are discussed in 1 and 2. Vander waal forces are very weak forces of attraction between atoms. These are not chemical attractions and are like universal gravitational force. These might be weak london dispersion forces and dipole-dipole interactions.

Electrostatic forces of attraction generally forms between a highly electropositive and a highly electronegative atom. The electropositive atom first contributes its electrons to the electronegative atom. As this is not sharing but a complete transfer of electrons, opposite charges develop on the atoms which eventually leads to electrostatic attraction. These bonds are called electrostatic or ionic bonds.

4. Polarity of water

Water is the best polar solvent. Water molecule contains one oxygen and two hydrogens. Oxygen atom is highly electronegative when compared to hydrogens. Hence the highly electronegative oxygen atom always tries to pull the shared pair of electrons towards itself from the hydrogens. This leads to the generation of a small negative charge on oxygen and a small positive charge on the hydrogen and we call this phenomenon as polarity of water molecule.

5. Water can form a maximum of 4 hydrogen bonds with its neighboring molecules. This is because the two hydrogens can form two hydrogen bonds with two electronegative atoms while one oxygen can form two hydrogen bonds with its two lone pairs.

6. Hydrophobic molecules are the molecules which can not dissolve in water. These molecules always try to escape from the vicinity of water molecules. For example hydrocarbons are hydrophobic due to their non-polar nature. Hydrophilic molecules are the water loving molecules. They can easily dissolve in water. For example methanol can easily dissolve in water due to its polarity.