1.3

A molecule with the molecular formula C5H10 is composed of nonpolar covalent bonds between the carbon and hydrogen atoms. Given the lack of polarity, which of the following bonds best describes how it is possible that multiple molecules of C5H10 can stick together. a. Hydrogen bonds b. Covalent bonds c. Hydrophobic interactions d. Van der wall interactions

d. Van der wall interactions

An ionic bond between two atoms is formed as a result of the a. sharing of electrons. b. loss of electrons from both atoms. c. loss of a proton from one atom. d. transfer of electrons from one atom to the other.

d. transfer of electrons from one atom to the other.

Polar covalent bonds are formed when the electrons in the bond are not shared equally between the two nuclei. Which one of these molecules contains polar bonds? (2 points) a. molecular oxygen b. methane c. propane d. water

d. water

Whereas ionic bonds form a/an __________, covalent bonds between atoms form a/an __________. These covalent bonds have a characteristic bond __________ and become stronger and more rigid when two electrons are shared in a/an __________. Equal sharing of electrons yields a/an __________ covalent bond. If one atom participating in the bond has a stronger affinity for the electron, this produces a partial negative charge on one atom and a partial positive charge on the other. These __________ covalent bonds should not be confused with the weaker __________ bonds that are critical for the three-dimensional structure of biological molecules and for interactions between these molecules.

salt molecule length double bond nonpolar polar noncovalent

Although covalent bonds are 10-100 times stronger than noncovalent interactions, many biological processes depend upon the number and type of noncovalent interactions between molecules. Which of the noncovalent interactions below will contribute most to the strong and specific binding of two molecules, such as a pair of proteins? a. electrostatic attractions b. hydrogen bonds c. hydrophobic interactions d. van der Waals attractions

a. electrostatic attractions

__________ play an important role in organizing lipid molecules with long hydrocarbon tails into biological membranes. a. Hydrogen bonds b. Ionic bonds c. Hydrophobic forces d. Van der Waals attractions

c. Hydrophobic forces