BCCB2000 Lecture 2 Questions

Question 1

When atoms approach closer than the sum of their van der Waals radii it results in a large increase in repulsion energy and an increase in stability. True or False?

Answer 1

False

Question 2

Which of these noncovalent forces in biological systems is usually the strongest? A. hydrogen bonds B. London dispersion forces C. hydrophobic interactions D. van der Waals forces

Answer 2

A. hydrogen bonds

Question 3

Which of the following weak interactions is not an electrostatic interaction? A. hydrogen bonds B. charge-charge interactions C. hydrophobic interactions D. van der Waals forces

Answer 3

C. hydrophobic interactions

Question 4

Use the words ‘intramolecular’ and ‘intermolecular’ in the following two statements. The redistribution, and rearrangement, of the valence electrons between at least two atoms in a molecule is known as a [a] interaction The redistribution, and rearrangement, of the valence electrons between at least two atoms in different molecules is known as a [b] interaction

Answer 4

Specified Answer for: a intramolecular Specified Answer for: b intermolecular

Question 5

The solubility of a molecule in water is determined by its ability to attract water and form hydrogen bonds. In the following use the either the word increase or the word decrease for your answer in the blank space provided: Polar groups in a molecule will [a] solubility. Nonpolar groups in a molecule will [b] solubility.

Answer 5

Specified Answer for: a increase Specified Answer for: b decrease

Question 6

A ‘salt bridge’ is usually best described as: A. An interaction between sodium chloride (salt) and some other molecule B. An interaction between any positive and any negative charge C. An interaction between sodium chloride (salt) and an amino acid D. An interaction between a positive amino acid and a negative amino acid within a protein

Answer 6

D. An interaction between a positive amino acid and a negative amino acid within a protein

Question 7

Why do atoms interact? A. Achieve a low energy state B. Gain more stability C. Achieve the greatest dispersion of energy D. Achieve the least dispersion of energy E. Achieve a high energy state

Answer 7

A, B, C

Question 8

Hydrophobic interactions: A. Result in hydrophobic groups forming outside a globular protein B. Are important in forming and maintaining simple molecules C. Cannot operate without water D. Are important in maintaining the structure of macromolecules.

Answer 8

C. Cannot operate without water D. Are important in maintaining the structure of macromolecules.

Question 9

Attractions of oppositely charged functional groups of proteins are sometimes called ________. A. salt bridges or ion pairing B. disulfide bridges C. London bridges D. hydrophilic bridges

Answer 9

A. salt bridges or ion pairing

Question 10

The three-dimensional structure of macromolecules is formed and maintained primarily through noncovalent interactions. Which of the following are not considered noncovalent interactions? A. hydrogen bonds B. van der Waals interactions C. carbon-carbon bonds D. ionic interactions E. hydrophobic interactions

Answer 10

C. carbon-carbon bonds

Question 11

Hydrophobic interactions arise from: A. The attractive force between non-polar molecules being greater than the attractive force between water B. Water excluding non-polar molecules which cannot form hydrogen bonds C. The thermodynamic effect of entropy D. Polar molecules minimising their contact with water E. Water trying to optimise hydrogen bonds with itself

Answer 11

B, C, E

Question 12

Select the statements that correctly apply to all forms of covalent bonds: A. Not effective at internuclear distances greater than 4Å B. Two atoms with unfilled electronic shells overlap and have increased electron density between them C. Low bond energy D. Most effective at internuclear distances less than 2Å E. Essential in forming and maintaining the 3D structure of macromolecules F. Electrons shared unequally G. Effective at large internuclear distances up to 10Å H. High bond energy I. Little or no sharing of electrons between atoms J. Electrons substantially shared between two particular atoms K. Essential to form the ‘backbones’ of macromolecules

Answer 12

A, B, D, F, H, J, K

Question 13

The Angstrom (Å) is a unit of length and is: A. 10^-6 metres B. 10^-7 metres C. 10^-8 metres D. 10^-9 metres E. 10^-10 metres F. 10^-11 metres G. 10^-12 metres

Answer 13

E. 10^-10 metres

Question 14

Which of the following interactions does not involve direct electrostatic interactions between a pair of atoms. A. Dispersion B. Dipole-dipole C. Charge-charge D. Covalent E. Hydrophobic

Answer 14

E. Hydrophobic

Question 15

Use the word smaller or larger for this statement: Van der Waal radii are [a] than atomic radii.

Answer 15

larger

Question 16

An ion-dipole and a charge-induced dipole both involve a [a]

Answer 16

ion/charge

Question 17

A weak temporary force of attraction that operates between all molecules (polar or nonpolar) over relatively short distances and its strength is proportional to the size and shape of a molecule. This is interaction is [a]

Answer 17

dispersion

Question 18

A dipole-dipole bond is the attraction between the δ+ end of one dipole and the δ- end of another dipole. True or False?

Answer 18

True

Question 19

Which of the following are due to covalent (C) or non-covalent (NC) interactions? Type either C or NC in the blank space following each statement. Formation and maintenance of protein tertiary structure… [a] Formation of the double helix of DNA… [b] Formation of cell membranes…[c] Formation of protein polymer structure…[d] The interaction of a small drug molecule with a protein…[e] The configuration of an amino acid…[f] Reversible and specific actions of proteins…[g]

Answer 19

Specified Answer for: a NC Specified Answer for: b NC Specified Answer for: c NC Specified Answer for: d C Specified Answer for: e NC Specified Answer for: f C Specified Answer for: g NC

Question 20

The nanometre (nm) is a unit of length and is: A. 10^-6 metres B. 10^-7 metres C. 10^-8 metres D. 10^-9 metres E. 10^-10 metres F. 10^-11 metres G. 10^-12 metres

Answer 20

D. 10^-9 metres

Question 21

When atoms approach at a distance greater than the sum of their van der Waals radii (but still within attraction distance) it results in a decrease in the energy of attraction and an increase in stability. True or False?

Answer 21

True

Question 22

Use the word merges or clashes for this statement: When two atoms form a covalent bond the van der Waals radius of one atom [a] with the other atom.

Answer 22

merges

Question 23

Four main macromolecules (polymers) are used in living organisms. Each are built from particular individual chemical components (monomers) connected together. Select the most likely and appropriate statements from the following: A. When starch dissolves in water glucose is formed B. When starch is degraded covalent bonds are broken and glucose is formed C. When albumin is broken down covalent bonds are broken and nucleic acids are formed D. The mass of albumin is less than the sum of the masses of its component monomers E. When DNA is broken down its covalent bonds are broken and amino acids are formed F. When lipid is dissolved in water containing detergent its individual components are released into solution. G. When albumin is dissolved in water water containing detergent its individual components are released into solution.

Answer 23

B, D, F

Question 24

Maleic acid and fumaric acid have identical molecular formulae and have all atoms connected in the same order but the maleic acid structure is in the cis configuration. This means that: A. The fumaric acid molecule cannot rotate B. The maleic acid molecule cannot rotate C. Maleic acid will have the same physical properties as fumaric acid D. That maleic acid OR fumaric acid have a double or triple bond in their structure E. That maleic acid AND fumaric acid have a double or triple bond in their structure F. Maleic acid will have different chemical properties from fumaric acid G. Fumaric acid is a trans geometric isomer of maleic acid H. Maleic acid is a chiral molecule

Answer 24

E, F, G

Question 25

Non-covalent interactions confer flexibility in macromolecules because they have a relatively low [a] that allows them to be constantly broken and reformed.

Answer 25

energy

Question 26

In an aqueous medium (i.e. water) polar groups and ions will be surrounded by [a] wheras hydrophobic groups will tend to cluster together.

Answer 26

water

Question 27

The distance between two atoms depends upon the [a] of the atom and the [b] of the bond.

Answer 27

[a] size [b] order

Question 28

One configuration of a molecule cannot be converted into another configuration of the same molecule without breaking one or more covalent bonds. True or False?

Answer 28

True

Question 29

Hydrogen bonds can occur when hydrogen is covalently bonded to atoms like nitrogen and oxygen. What property of nitrogen and oxygen is important for this? A. atomic mass B. ionizability C. hydrophobicity D. electronegativity

Answer 29

D. electronegativity

Question 30

A change from one conformation of a molecule to another involves: A. rotation about bonds only B. breaking and reforming of covalent bonds C. inversion about a centre of symmetry D. Any of the above

Answer 30

A. rotation about bonds only

Question 31

Which of the following statements about the covalent bond are appropriate? A. A dihedral angle is the angle between four sequential covalently bonded atoms B. The longer the bond the stronger the bond C. Covalent bonds cannot be any longer than 4Å D. The greater the number of shared electrons the lower the bond strength E. Important in forming the long linear polymer (amino acid) chains of proteins F. The higher the bond order the stronger the bond

Answer 31

A, C, E, F

Question 32

The aggregation of nonpolar molecules in water is thermodynamically due to the: A. increased entropy of the nonpolar molecules when they associate. B. decreased enthalpy of the system. C. increased entropy of the water molecules. D. very strong van der Waals forces among the nonpolar molecules or groups

Answer 32

C.increased entropy of the water molecules.

Question 33

Polarisation of a molecule means that there is an [a] distribution of electrons over the molecule.

Answer 33

Unequal/symmetric

Question 34

Charge-charge electrostatic interactions are: A. proportional to the type and size of the charges B. inversely proportional to the distance between the two charges C. inversely proportional to the type and size of the charges D. proportional to the distance between the two charges

Answer 34

A. proportional to the type and size of the charges B. inversely proportional to the distance between the two charges

Question 35

Select the correct statements about atom size: A. A carbon atom is slightly larger than a nitrogen atom but smaller than an oxygen atom B. A sulphur atom is larger than carbon, oxygen, and nitrogen atoms C. An oxygen atom is slightly smaller than a nitrogen atom D. A carbon atom is slightly larger than a nitrogen atom and an oxygen atom E. A hydrogen atom is about half the size of nitrogen and oxygen atoms. F. A carbon atom is about twice the size of a hydrogen atom G. A magnesium atom is more than twice the size of a carbon atom.

Answer 35

A, D, E, F, G