Properties of Biological Molecules

Question 1

Describe Covalent bonds?

Answer 1

Strong
Short
Share electrons

Question 2

Describe noncovalent bonds?

Answer 2

Weak
Long
Attraction only

Question 3

What bonds make up carbohydrates?

Answer 3

Glycosidic

Question 4

What bonds are between monomers of lipids?

Answer 4

Esters

Question 5

Describe and give an example of an electrostatic interaction?

Answer 5

Charge Charge interaction between two completely charged ions, such as NaCl and ionic bond, or salt bridges. Salt bridges are interactions betweeen two amino acids in a protein.

Question 6

What is Coulomb’s law used for and when using Coulomb’s Law what does F>0 and <0mean?

Answer 6

It is used to measure how attractive two ions are to each other. F>0 means the ions are repulsing and F<0 means they are attracted.

Question 7

What is the equivalent to Coulomb’s law in a biological environment?

Answer 7

Relative Permittivity is added into the equation. F=k (q1q2)/Dr^2

Question 8

What is the energy of interaction equation used for?

Answer 8

To measure how much energy is required to separate two ions. E=k (q1q2)/ Dr

E<0 is attraction

Question 9

If D of water is 80 and D of methanol is 33 how would the energy of interaction change if you made an aqueous solution with Mg ions and Br ions in methanol compared to water?

Answer 9

The energy of interaction would increase as you are dividing by a smaller number.

E=k (q1q2)
_______
Dr

Question 10

What does it mean to say dipole interaction?

Answer 10

There is a partial charge. They can be polar and induced (polarizable)
Charged attraction

Question 11

What is a Dispersion interaction?

Answer 11

Type of electrostatic interaction, also called Van Der Waals or hydrophobic interactions. Charged attraction. An example is stacking benzene rings or stacking nucleotides

Question 12

Describe Hydrogen bonds.

Answer 12

Type of electrostatic interaction. A hydrogen atom is shared between two molecules. Example is nucleotide base pairing.

Question 13

Describe hydrogen bonds at solid liquid and gas states?

Answer 13

In a solid phase hydrogen bonds are optimal . Liquid has sub optimal hydrogen bonds and gasses do not have hydrogen bonds.

Question 14

Describe why Ice floats.

Answer 14

Ice is less dense than water due to the distance between hydrogen bonds. Density is how tightly packed molecules are and they are more tightly packed in water than ice.

Question 15

Do hydrogen bonds use or release energy when they form?

Answer 15

Hydrogen bonds release energy when they are formed and use energy to break.

Question 16

Difference between cohesion and adhesion?

Answer 16

Cohesion is attraction to self and adhesion is attraction to other. So water molecules attracted to more water and water attracted to other polar substances.

Question 17

What happens to energy when noncovalent interactions break and form?

Answer 17

Breaking:use
Forming:release

Question 18

What happens to energy when covalent bonds break and form?

Answer 18

Breaking:release
Forming:use

Question 19

If pH is less than pKa are molecules protonated or deprotonated?

Answer 19

Protonated

Question 20

If pH is greater than pKa are molecules protonated or deprotonated?

Answer 20

Deprotonated, less H ions floating around

Question 21

What is the pKa of carboxyl on amino acids and the amine?

Answer 21

Carboxyl is about 2 and amine is around 9

Question 22

If pH is less than pI what is the overall charge?

Answer 22

Positive charge

Question 23

If pH is greater than pI what is overall charge?

Answer 23

Negative

Question 24

If pH=pI what is the charge?

Answer 24

No net charge because pI is the pH where all molecules have overall charge of 0.

Question 25

During Isoelectric Focusing when do proteins stop moving and how does this work?

Answer 25

Isoelectric focusing changes the pH as you move further down the gel so you are separating proteins by pI. Proteins stop moving when they are no longer charged, which means that pH=pI.

Question 26

At a high pH (pH>pI) is the protein protonated or deprotonated and is it soluble or insoluble?

Answer 26

Deprotonated and soluble. Molecules are negatively charged and repel each other

Question 27

At isoelectric point do proteins aggregate or repel and become soluble or insoluble?

Answer 27

Aggregate and precipitate out

Question 28

if pH is less than pI are proteins protonated or not and soluble or insoluble?

Answer 28

They are protonated and soluble At low pH the protins are soluble because of repulsions due to their positive charges.

Question 29

Where does the lowest solubility occur?

Answer 29

at the isoelectric point

Question 30

What is an open system?

Answer 30

Energy can be exchanged between system and surroundings

Question 31

What is a closed system?

Answer 31

Energy cannot leave the system

Question 32

What type of metabolic reaction (ababolism/catabolism) has a higher rate of entropy?

Answer 32

Catabolic, large molecules are broken down into smaller ones releasing energy.

Question 33

What is the Gibbs Free energy equation?

Answer 33

G=H-T^S

Question 34

What does it mean if Enthalpy changes?

Answer 34

the system is not closed

Question 35

What drives the sign of delta G?

Answer 35

TS

Question 36

What does a negative G mean?

Answer 36

Free energy is released and the reaction is exergonic and favorable as well as spontaneous.

Question 37

When Q=K what happens?

Answer 37

The reaction is at equillibrium

Question 38

If Q

Answer 38

the reaction goes towards the products

Question 39

If Q>K what happens?

Answer 39

the reaction goes to the left to reactants