(a). Phospholipids are amphipathic molecules which have hydrophilic and hydrophobic regions. Explain how this feature benefits the cell. (Give ONE reason) (2) (b). Give ONE difference between a saturated phospholipid and an unsaturated phospholipid, (2)
Nucleotides
It is an organic molecule made up of three basic components- a nitrogenous base, phosphate,and pentose sugar. The nucleotides are important for metabolic reactions andthe formation of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
Nucleic Acids
Nucleic acids are essential biomolecules present in prokaryotic and eukaryotic cells and viruses. They carry the genetic information for the synthesis of proteins and cellular replication. The nucleic acids are of two types: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The structure of all proteins and ultimately every biomolecule and cellular component is a product of information encoded in the sequence of nucleic acids. Parts of a DNA molecule containing the information needed to synthesize a protein or an RNA are genes. Nucleic acids can store and transmit genetic information from one generation to the next, fundamental to any life form.
Lipid Bilayer is the universal basis for the cell membrane. The bilayer structure is composed of specific properties of lipid molecules, which led them to assemble spontaneously into bilayers even under simple artificial conditions. Phospholipids are the most abundant membrane lipids. It has a polar head group and two hydrophobic hydrocarbon tails. The tails are usually fatty acids and their length ranges 14 and 24 carbon atoms.
The shape and the amphipathic nature of the lipid molecules led them to form bilayers spontaneously in aqueous environments. The hydrophilic part of the lipid molecule dissolves readily in water because it contains charged groups or uncharged molecules that can form favorable electrostatic interactions or hydrogen bonds with water molecules but the hydrophobic ones are insoluble in water molecules, hence it cannot form interactions with water molecules. Therefore the hydrophobic molecules aggregate together to prevent the hindrance water molecules in it. Similarly, it is energetically most favorable arrangement resulting to form a lipid bilayer.
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