FATS AND LIPIDS

by Marvin B. Gonzaga

Lipids •  a large and diverse group of naturally occurring organic compounds that are related by their solubility in nonpolar organic solvents (e.g. ether, chloroform, acetone & benzene) and general insolubility in water. 

• many lipids incorporate fatty acids, small organic compounds consisting of a long carbon chain with an acidic carboxyl group at one end.

• Major lipid groups include fats, phospholipids, steroids, and waxes.

Fats and Oils • Lipids with one, two, or three fatty acids that dangle like tails from a small alcohol called glycerol.

• Most neutral fats, including, including butter and vegetable oils, have 3 fatty acid tails, so they are called triglycerides.

• Triglycerides that are solid at room temperature are called fats while those that are liquid are called oils.

Saturated, Mono-

unsaturated, and Poly-unsaturated

Fats

• The terms saturated, mono-unsaturated, and poly-unsaturated refer to the number of hydrogens attached to the hydrocarbon tails of the fatty acids as compared to the number of double bonds between carbon atoms in the tail.

• the fatty acids in saturated fats contain the maximum possible amount of hydrogens. The hydrocarbon chains in these fatty acids are, thus, fairly straight and can pack closely together, making these fats solid at room temperature. 

Unsaturated Fats

• Unsaturated fats have one or more double bonds that kink their carbon chains. These kinks keep unsaturated fats from packing tightly, making these fats liquid at room temperature.

Phospholipids • Have two fatty acid tails attached to a phosphate-containing head. The tails are hydrophobic, but the phosphate makes the head hydrophilic.

• The most abundant lipids in cell membranes, which have two layers of lipids.

Steroids • Lipids with a rigid backbone of four carbon rings and no fatty acid tails. All eukaryotic cell membranes contain them.

• Cholesterol, Estrogen, and Testosterone are steroids.

Waxes • Complex, varying mixture of lipids with long fatty acid tails bonded to long-chain alcohols or carbon rings. The molecules pack tightly, so the resulting substance is firm and water-repellent.

NUCLEIC ACIDS

Nucleic Acids

• Organic molecules that allow organisms to transfer genetic information from one generation to the next.

• Composed of nucleotides, each of which consists of a sugar with a five-carbon ring, bonded to a nitrogen-containing base and one or more phosphate groups.

DNA (Deoxyribonucleic acid)• Consists of two nucleotide

chains twisted into a double helix.

• DNA is organized into chromosomes and found within the nucleus of cells. It contains the "programmatic instructions" for cellular activities.

• Nitrogenous bases of adenine (A), guanine (G), cytosine (C), and thymine (T)

RNA (Ribonuclei

c acid)

• single stranded nucleic acid,  whose nitrogenous bases include adenine (A), guanine (G), cytosine (C) and uracil (U).

• plays a major role in protein synthesis as it is involved in the transcription, decoding, and translation of the genetic code to produce proteins. It is also a component of cell organelles called ribosomes.

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