Unit 1: Chemistry for Biology

Question 1

organic molecule

Answer 1

• molecule that contains at least one C-H bond

Question 2

inorganic molecule

Answer 2

• molecule that doesn’t have any C-H bonds, many ions and small molecules that are relevant to biology (such as CO2) fall into this category

Question 3

What are the three components an H-bond requires?

Answer 3

1) an electronegative atom: O, N, or S
2) a hydrogen atom attached to that electronegative atom, forming a polar bond
3) an electronegative atom on another molecule (or even within the same molecule) with a free lone pair of electrons that can attract the hydrogen atom above

Question 4

What type of bonds are H-bonds and why do they have their own classification? (3)

Answer 4

• type of permanent dipole to permanent dipole interaction
• bonds tend to be relatively strong and are very significant
• strong as a non-covalent interaction because of partial sharing of the lone pair of electrons which gives H-bonds a small amount of covalent bond character

Question 5

electronegativity (4)

Answer 5

• all atoms in molecules have a certain (and relative) amount of pull or attraction on nearby elections, especially those on adjacent bonds
• strength of attraction increases up and to the right of the periodic table
• scale ranges from 0.7 to 4.0
• can lead to uneven sharing of electrons within a bond

Question 6

non-polar covalent bond

Answer 6

• electrons shared equally between 2 atoms

- a covalent bond between atoms that have the same, or nearly the same electronegativity

Question 7

polar covalent bonds

Answer 7

• electrons shared unequally between 2 atoms

Question 8

ionic bond

Answer 8

• electrons removed from one atom and held by the other, forming and electrostatic bond (opposite charges)

Question 9

polar (molecule)

Answer 9

• a molecule that has regions of positive and negative charges

Question 10

nonpolar

Answer 10

• describes compounds that do not have regions of positive and negative charge

Question 11

hydrophilic

Answer 11

• “water loving”

- describes a class of molecules with which water can undergo hydrogen bonding

Question 12

hydrophobic

Answer 12

• “water fearing”

- describes a class of molecules poorly able to undergo hydrogen bonding with water

Question 13

hydrophobic effect

Answer 13

• exclusion of non-polar molecules by polar molecules, which drives biological processes such as the formation of cell membranes and the folding of proteins

Question 14

What are the types of interactions that are important in cell biology?

Answer 14

1) induced dipole - induced dipole
2) Permanent dipole - permanent dipole
3) Hydrogen bonding
4) Permanent dipole - induced dipole
5) Ionic - permanent dipole
6) Ionic - induced dipole
7) Ionic

Question 15

What is the general trend of strongest to weakest bonds?

Answer 15

1) Covalent 
Non-Covalent:
2) Ionic
3) Ion-PD
4) H-bond
5) PD-PD
6) PD-ID, Ion-ID
7) ID-ID

Question 16

What bonds are more favourable in a case where more than one type of interaction is possible?

Answer 16

• a molecule or region of a molecule will always favour making the strongest interaction possible

Question 17

functional groups

Answer 17

• within biologically relevant molecules, atoms or groups of atoms that have interesting chemistry (polar, lots of electrons, charges or partial charges, etc)
• often perform a function in a reaction or strong interactions
• tend to perform a certain type of chemistry regardless of what type of molecule they are attached to