Chemical Foundations of Life

Question 1

What are the major classes of Macromolecules?

Answer 1

Nucleic acids, proteins, carbohydrates, lipids

Question 2

The hGH molecule binding with the hGH receptor is a result of _

Answer 2

Specific, noncovalent bonding interactions

Question 3

When hGH is bound to its receptor what happens?

Answer 3

A signal is transmitted across the cell membrane and triggers cell growth

Question 4

Covalent bonding cannot account for the complex structures biological molecules form. What kind of bonding allows large macromolecule to fold into 3D structures? How do the weaker bonds allow for this?

Answer 4

Weaker, noncovalent interactions. These noncovalent interactions allow the structure to flex.

Question 5

Why do macromolecules have to assume SPECIFIC 3d strutures?

Answer 5

It is important for their function

Question 6

How many types of noncovalent bonding? What are the types of noncovalent bonding?

Answer 6

There are 7. Charge-charge (ionic), charge-dipole, dipole-dipole, charge-induced dipole, dipole-induced dipole, dispersion or van der waals, hydrogen bonding

Question 7

What is an ionic bond?

Answer 7

A bond formed between two opposite charged atoms sharing the valence e-

Question 8

What happends to ionic bonds in water?

Answer 8

Ionic bonds come apart because water has a large dielectric constant.

Question 9

What causes a dipole moment in a molecule?

Answer 9

An asymmetric distribution of charge

Question 10

What is a common molecule with a a strong dipole moment?

Answer 10

H2O, a very polar molecule

Question 11

How does a a benzene ring with no permanent dipole moment or net charge become polar?

Answer 11

e- can be displaced within a ring

Question 12

Why do planar molecules like benzene rings stack?

Answer 12

The induced termporary dipoles of the e- give rise to mutally attracted dipoles known as Van der Waals interactions

Question 13

What is optimal Van der Waals radius?

Answer 13

It is when the energy of the interaction is most negative, its highest energy - this is most effective radius for close molecular packing

Question 14

What happens with closer contact than optimal vdwaals distance?

Answer 14

Molecules will repel each other

Question 15

How do van der waals forces increase the stability of biomolecules?

Answer 15

Although vdwaals are weak on their own, when they come together as a collective they can make significant contributions to the stability of biomolecules

Question 16

How many H-bonds can one molecule of water make?

Answer 16

Up to 4

Question 17

In a water molecule what are the 2 donors and 2 acceptors of h-bonds?

Answer 17

Donors are the 2 hydrogen atoms and the two acceptors are the two unpaired electrons on the oxygen atom

Question 18

How does water act like a glue?

Answer 18

Has a high melting/boiling point

Question 19

Water as is a good solvent because?

Answer 19

Dissolves ionic molecules, negative end interact with cations and positively end interacts with anions

Question 20

Polar AAs vs Non-polar Aas, which likes water?

Answer 20

Polar AAs wil like to interact with water and Non-polar wont. Non-polar AAs will be folded on the inside of proteins

Question 21

Why does a nonpolar molecule cause a loss of entropy to the water molecules around it?

Answer 21

The unfavorable loss of entropy is due to water turning away from the hydrophobic water into an ordered structure to minimize interaction with the hydrophbic molecule

Question 22

What is the hydrophobic affect?

Answer 22

The aggregation of non polar molecules to minimize the ordered water around - maintaining more entropy

Question 23

What is a bilayer vesicle?

Answer 23

When an amphipathic molecule forms a cylinder like structure in aqueous solution

Question 24

What is an amphpathic phospholipid and what do they compose?

Answer 24

A hydrophobic head with a hydrophilic tail, they compose membranes

Question 25

How are kA and pKa related? Is low pKa acidic or basic?

Answer 25

They have an inverse relationship, a high Ka has a low pKa. The lower the pKa is, the more acidic it is.

Question 26

Acid/Base: which is proton donor and which accepts?

Answer 26

Acid donates protons and bases accept protons.

Question 27

What does the strength of an acid mean?

Answer 27

How well or how likely it will lose its proton.

Question 28

How many AAs can be protonated?

Answer 28

7