LEC 3: Molecular interactions

Question 1

What are the types of molecular interactions (5), and their interaction strength (kJ/mol)

Answer 1

Covalent bond (>210)
Ionic bonds (4-80)
Hydrogen bonds (4-20)
Van der Waal interactions (2-4)
Hydrophobic effect (3)

Question 2

Biomolecules are stable because they are constructed with ___. However, the remarkable structure and function of cells are stabilized by ___.

Answer 2

Strong covalent bonds

Weak intermolecular interactions

Question 3

Noncovalent bonds are ___, but when many are present within a given macromolecule, their ___ can sum to hundreds of kJ, sufficient to provide __ to macromolecular structures.

Answer 3

Individually weak
Energy
Stability

Question 4

It is the ___ of noncovalent bonds that make them so essential, they can be broken and reformed, giving biological structures ___ necessary to their function

Answer 4

Weakness

Dynamic flexibility

Question 5

What are the characteristics of chemical bonds (5)

Answer 5

1. Forces that hold atoms together to make molecules
2. Driving forces behind chemical reactions
3. Formed between atoms that lack a full valence shell
4. Formed to achieve a filled valence shell, the most energetically stable arrangement
5. Sharing or transferring elections

Question 6

What are the characteristics of Covalent bonds (3)

Answer 6

1. Used to store energy and to form biomolecules
2. Strongest bonds
3. Results in electron sharing (orbital overlaps)

Question 7

Characteristics of Ionic bonds (3)

Answer 7

1. A charged group on 1 molecule, or charged atom, chemically binds with a molecule/atom carrying the opposite charge
2. Ionized elements play a role in enzymatic reactions and help stabilize DNA, RNA, and protein molecules
3. Form when an element is able to lose 1, 2, 3 electrons and the other the to accept electrons

Question 8

What are the 5 essential ionized elements require by life?

Answer 8

1. Ca2+
2. K+
3. Na+
4. Mg2+
5. Cl-

Question 9

What are the characteristics of polarity in moleucles (4)

Answer 9

1. Unfair sharing of electrons
2. Creates dipoles
3. Induces hydrophilic nature
4. Are permanent dipoles

Question 10

What are the characteristics of Hydrogen bonds (3)

Answer 10

1. Interactions between two polar molecules involving H
2. Strong, selective and directional
3. Important form of bonding in biological systems

Question 11

Define H-bond Donors

Answer 11

An electronegative atom (N,O,S) that is covalently bonded to a H atom

Question 12

Define H-bond Acceptor

Answer 12

An electronegative atom that contains a pair of non-bonded electrons (N,O)

Question 13

What are the characteristics of Van der Waals interactions? (2)

Answer 13

1. weak electrostatic interactions are possible between neutral and nonpolar molecules
2. Random fluctuations in electrons distribution sets up a temporary dipole in a molecule

Question 14

What are the characteristics of Hydrophobic effect (3)

Answer 14

1. Occur between molecules that cannot interact with water
2. They coalesce/aggregrate together to minimize their surface area contact with water molecules
3. Important to structure of DNA and proteins and membranes in cells