Lipids Overview

Lipids

• Lipids are organic substances including fats and fat-like substances (phospholipid, wax, steroid, sphingolipid)
• Regardless of structure, they have large amounts of C-H bonds (hydrocarbon chains) which enable grouping
• Lipids are important components of cell membranes, aiding in fat digestion, providing water resistance and protection
• Lipids include phospholipids, waxes, steroids, and triglycerides
  • Phospholipids are major components of cell membranes.
  • Waxes provide water resistance and protection.
  • Steroids have hormonal signaling, cell response and growth functions.
  • Triglycerides are involved in energy storage, thermal insulation and carrying fat-soluble vitamins
• Main elements of lipids include carbon, hydrogen, and oxygen.
• Some lipids contain other elements like phosphorus, sulfur, and nitrogen
• Triglycerides consist of one glycerol molecule bonded to three fatty acids.
  • Glycerol is a three-carbon chain bonded to hydrogen atoms and alcohol groups.
  • Fatty acids are hydrocarbon chains with a carboxyl group at one end.

Fatty Acids

• There are two types of fatty acids: saturated and unsaturated
  • Saturated fats have all carbon atoms bonded to other carbon and hydrogen atoms, mostly solid at room temperature.
  • Unsaturated fats have some carbon atoms bonded via double bonds to other carbon atoms. These cause kinks in the molecule, leading to liquid form at room temperature.

Phospholipids

• Phospholipids are composed of fatty acid chains attached to a glycerol backbone.
• Phospholipid molecules are amphipathic, meaning they have a polar head and a nonpolar tail. This arrangement is crucial to cell membrane structure.

Steroids

• Steroids are small lipids where the hydrocarbon backbone is linked into four rings.
• Cholesterol is an important steroid, providing structure to cell membranes and aiding in digestion of dietary fats.

Waxes

• Waxes are components of organisms such as cuticles, covering leaves and stems of plants and protective coverings on skin and fur of animals.

Lipids in Living Organisms

• Lipids act as solvents for fat-soluble vitamins and hormones.
• They prevent water loss from the skin.
• They are crucial components of cell structures, including cell membranes.
• They provide insulation and protection against extreme cold.
• Lipids store energy, and provide twice as much energy per pound as carbohydrates.

Nucleic Acids

• Nucleic acids are organic compounds that store genetic information, transmitting it from one generation to the next.
• Nucleic acids function during protein synthesis by carrying the code needed to form specific proteins.
• Two main types: Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA)
  • DNA is a double-stranded helix.
  • RNA is a single-stranded structure (sometimes a double helix)

Elements in Nucleic Acids

• Nucleic acids contain nitrogen, oxygen, carbon, phosphorus, and hydrogen.

DNA vs. RNA Comparison

• DNA replicates and stores genetic information. It acts as a blueprint for all genetic information.
• RNA converts genetic information from DNA to a format used to build proteins, then moves it.

Nucleic Acid Structure

• Nucleotides are the building blocks of nucleic acids. Each nucleotide contains a phosphate group, a five-carbon sugar (deoxyribose in DNA, ribose in RNA), and a nitrogenous base.
• DNA consists of two strands arranged in a double helix, while RNA has a single strand (sometimes a double helix).
• DNA is a much longer polymer than RNA.

Nucleic Acid Sugar

• DNA's sugar is deoxyribose.
• RNA's sugar is ribose.

Nucleic Acid Bases

• DNA bases include Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).
• RNA bases include Adenine (A), Uracil (U), Guanine (G), and Cytosine (C).

Base Pairs

• A pairs with T in DNA; A pairs with U in RNA.
• C pairs with G

Nucleic Acid Reactivity

• DNA is more stable than RNA due to its deoxyribose sugar.
• RNA is more reactive and not stable in alkaline conditions, meaning it's more easily susceptible to enzyme attack.