Biology Nutrition and Digestion

Running Head: Biology Nutrition and Digestion 1
Understand lipids, carbohydrates, and proteins
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Biology Nutrition and Digestion 2
2.0 Understand lipids, carbohydrates, and proteins
2.1 Structure and functions of phospholipids and cholesterol and structural differences between
saturated, mono-unsaturated and polyunsaturated fatty acids
Phospholipids are mainly found in the cell membrane. They are made up of a glycerol molecule,
a phosphate group, and two fatty acids. Structurally, a phospholipid is made up of two
hydrophilic fatty acids tails and a hydrophobic phosphate group head (Tanaka, Fujimura-
Kamada, and Yamamoto, 2010). On the other hand, cholesterol which consists of four
hydrocarbons attached to form a large steroid structure helps in membrane fluidity in animals.
Saturated fatty acids are straight hydrocarbon chains saturated with hydrogen. They contain 12-
22 carbon atoms. Unsaturated fatty acids are made up of 16-22 carbon chains and have a double
bond found in different positions. Polyunsaturated fatty acids are long hydrocarbon chains with a
double bond between the third and fourth carbon and a methylene group between the double
bonds (Mozaffarian, Micha and Wallace, 2010).
2.2 Glycosidic bond formation and the structure and functions of monosaccharide, disaccharides
and polysaccharides
Glycoside bond is a covalent bond formed between a molecule from a saccharide and a hydroxyl
group from a compound like alcohol through condensation reaction (Leemhuis, Pijning,
Dobruchowska, Dijkstra, & Dijkhuizen, 2012). Depending on monosaccharaides present there
are three forms which include, Monosaccharide which has one polyhydroxy aldehyde unit,
whereas Disaccharides has two monosaccharide units joined together through a covalent bond
like sucrose and Oligosaccharide has 3 and ten monosaccharide units like farinose. A