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Question 22

CO₂, O₂, N₂

Answer 22

What are three biologically important gases that are non-polar and therefore not soluble in water.

Question 23

mixed polar and non polar character

Answer 23

Amphipathic molecules have

Question 24

poor

dissolve

chloroform and benzene,

Answer 24

Non-polar solvents are poor/good solvents for polar molecules, but easily dissolve/don’t dissolve non-polar molecules.

Name two non-polar solvents

Question 25

hydration (A process in which water molecules are attracted to and form weak bonds with the soluble species.)

This occurs when hydrophilic compounds dissolve in water.
Formation of hydration spheres stabilise ions or dipoles

Answer 25

Water as ionic solvent.

The attractive/ repulsive forces between charged compounds is partially neutralised by _____

Question 26

1. H-bonds
2. Ionic interactions
3. Hydrophobic interactions
4. Van der Waals interactions

Answer 26

Name the four types of noncovalent (weak) interactions among biomolecules in aqueous solvent.

Question 27

weaker

Answer 27

Are noncovalent interactions weaker or stronger than covalent bonds?

Question 28

1. 3D shape of proteins are influenced by these interactions
2. Binding of hormone to cellular receptor protein is the result of multiple weak interactions

Answer 28

Noncovalent (‘Weak’) interactions are continually forming and breaking, as strength of solute-solvent (water) is nearly as favorable as solute-solute.

The cumulative effect can be very significant. Give two examples.

Question 29

Forces that hold nonpolar regions together

Minimising ordered water molecules surrounding compound (water cage) to achieve greater thermostability (higher entropy)
Consider the behaviour of amphipathic molecules in water

See diagram below where: The hydrophobic portions of amphipathic molecules (a fatty acid here) interrupt the H-bonded molecular structure of water.

The decreased entropy (stable ordering of water at the margin) is energetically unfavourable

Answer 29

Hydrophobic interactions are?

Explain a bit.

Question 30

Answer 30

Watercages picture.

Question 31

group together in water

Answer 31

In order to achieve greater thermodynamic stability, and minimise the amount of hydrophobic area exposed to the polar solvent non-polar, hydrophobic regions of amphipathic compounds (e.g. fatty acids or membrane lipids) tend to

Question 32

micelles

micelles

Micelles are shaped with the non-polar regions tending to group together leaving the polar regions on the outside

Answer 32

Clusters of lipids condense into _____?
These, _____ are energetically more favourable because no ordered “water cages”. Explain how these clusters are shaped.

Question 33

a state in which a chemical system is neither consuming or releasing heat energy.

Answer 33

Thermodynamic stability is

Question 34

1. hydration
2. “fit”, example is e.g. binding substrates to enzymes displaces water

Answer 34

1. In H-bonding between polar molecules the binding of polar molecules reduces _____.
2. Non covalent interactions must provide a good _____ . give an example of this bonding.

Question 35

1. Very simply, the attraction of opposite charges for each other.
2. the cube of the radius (volume), so that distance is important in bond strength (must be a good ‘fit’)

Answer 35

1. Ionic/electrostatic interactions are?
2. The attraction decreases with

Question 36

London forces

Description:

• Weak transient dipole attractions
• surrounding electron clouds influence each other
• Counter-balanced by repulsive forces of 2 electron clouds, to give final van der Waals radius
• These are extremely close proximity between atoms.
• i.e. require exact fit of surfaces

Answer 36

Van der Waals interactions are also called ?

Describe these forces?

Question 37

Yes

Answer 37

Do all the noncovalent bonds in water involve electrical charges. yes or no?

Question 38

Van der Waals interactions

Answer 38

Which are the weakest of all non-covalent forces?

Question 39

H₂O

H₃O⁺ and OH⁻

ionisation

Answer 39

Not all water molecules are in the form ___. A small degree of ionisation occurs in water so there are some ___ and ___ as well. This is called the _____ of water.

Question 40

1. About 1 in one ten million
2. equilibrium

Answer 40

1. What numbers of water molecules are ionised?
2. These ions are in _____ with the water molecules

Question 41

Hydronium ions H₃O⁺

Answer 41

H⁺ free protons do not exist in solution even though we usually show it. Instead what type of ions exist?

Question 42

electrical conductivity.

Answer 42

Ionisation of water is measured by its?

Question 43

H₃O⁺, OH^-

Answer 43

Pure water carries electrical current as ____ migrates toward the cathode and _____ toward the anode.