Fats and Fatty Acids

Fats (Lipids)

Composition

• Fats are a type of macromolecule also known as lipids.
• Composed of carbons, hydrogens, and oxygens.
• Unlike carbohydrates, fats have a significantly smaller amount of oxygen relative to carbon and hydrogen.

Monomer Structure: Fatty Acids

• Basic subunit of fats is the fatty acid.
• Predominantly hydrocarbon chains (chains of carbon with hydrogen atoms attached).
• Differences between fatty acids:
  • Length of the carbon chain.
  • Types of bonds between the carbon atoms.
• Each fatty acid has a carboxyl functional group attached, containing oxygen.

Types of Fatty Acids

Saturated Fatty Acids (e.g., Palmitic Acid)

• Every carbon atom is attached to as many hydrogen atoms as possible (saturated with hydrogen).
• Linear (straight) structure.
• Can stack nicely on top of each other.
• Solid at room temperature.
• Most animal fats are saturated fats.

Monounsaturated Fatty Acids (e.g., Oleic Acid)

• Similar to saturated fatty acids but contain one double bond between two carbon atoms.
• The double bond means the carbon is not saturated with hydrogen atoms.
• The double bond creates a kink in the fatty acid structure.
• Do not stack well due to the kinks.
• Liquid at room temperature.
• Predominantly plant oils (e.g., peanut oil, olive oil).

Polyunsaturated Fatty Acids (e.g., Linoleic Acid)

• Contain multiple double bonds between carbon atoms (many unsaturated carbons).
• More kinks in the fatty acid structure compared to monounsaturated fats.
• Liquid at room temperature.

Triglycerides

• The body cannot store fatty acids in their original long-chain form.
• Triglycerides are formed through a dehydration process where three fatty acids attach to a glycerol molecule.
• Glycerol: Has three carbons, eight hydrogens, and three oxygens ($C<em>3H</em>8O_3$).

Process

• Water is removed ($H_2O$).
• Hydrogens are removed from the glycerol.
• $OH$ groups are removed from the fatty acids.
• Three fatty acids connect to the glycerol molecule.

Function

• Triglycerides are stored as fat deposition and serve as energy reserves.
• Also used for cushioning, support, and anchorage, holding organs in place.

Variability

• Types of fatty acids attached to glycerol can vary (saturated, monounsaturated, polyunsaturated).
  • All saturated: solid at room temperature.
  • All mono or polyunsaturated: liquid at room temperature.

Example: Cocoa Butter

• Contains palmitic acid (saturated), oleic acid (monounsaturated), and a polyunsaturated fatty acid.

Summary

• Fats (lipids) consist of fatty acids, which can be saturated, monounsaturated, or polyunsaturated.
• These fatty acids are stored as triglycerides, playing roles in energy storage, cushioning, and support.