Answer:
We identify nucleic acid strand orientation on the basis of important chemical functional groups. These are the <u>phosphate</u> group attached to the 5' carbon atom of the sugar portion of a nucleotide and the <u>hydroxyl</u> group attached to the <u>3'</u> carbon atom
Explanation:
Nucleic acids are polymers formed by a phosphate group, a sugar (ribose in RNA and deoxyribose in DNA) and a nitrogenous base. In the chain, the phosphate groups are linked to the 5'-carbon and 3'-carbon of the ribose (or deoxyribose) and the nitrogenous base is linked to the 2-carbon. Based on this structure, the nucleic acid chain orientation is identified as the 5'-end (the free phosphate group linked to 5'-carbon of the sugar) and the 3'-end (the free hydroxyl group in the sugar in 3' position).
Answer:
a): not necessarily due to London Dispersion Forces and dipole-dipole interactions.
b): not necessarily due to London Dispersion Forces.
Explanation:
There are three major types of intermolecular interaction:
- Hydrogen bonding between molecules with H-O, H-N, or H-F bonds and molecules with lone pairs.
- Dipole-dipole interactions between all molecules.
- London dispersion forces between all molecules.
The melting point of a substance is a result of all three forces, combined.
Note that the more electrons in each molecule, the stronger the London Dispersion Force. Generally, that means the more atoms in each molecule, the stronger the London dispersion force. The strength of London dispersion force between large molecules can be surprisingly strong.
For example, 
(water) molecules are capable of hydrogen bonding. The melting point of at 
is around 
. That's considerably high when compared to other three-atom molecules.
In comparison, the higher alkane hexadecane (
, straight-chain) isn't capable of hydrogen bonding. However, under a similar pressure, hexadecane melts at around 
above the melting point of water. The reason is that with such a large number of atoms (and hence electrons) per molecule, the London dispersion force between hexadecane molecules could well be stronger than that the hydrogen bonding between water molecules.
Similarly, the dipole moments in HCl (due to the highly-polar H-Cl bonds) are much stronger than those in hexadecane (due to the C-H bonds.) However, the boiling point of hexadecane under standard conditions is much higher (at around 
than that of HCl.
