> See also: > - [[Biological Membrane]] # Lipids **Lipids** are one of the four main [[Biological Macromolecules]]. **Steroids** are made out of lipids and allow for long-term signals - Ex: testosterone, estrogen Fatty Acids are carboxylic acids with long-chain hydrocarbon side groups ## Structure & Classifications > [[Phospholipases]] Lipids can be classified *based on their backbone* ### Saturated vs Unsaturated - Presence of double bonds affects physical properties - Saturated: Entirely fileld with hydrogen molecules - Unsaturated: Replaced two hydrogen molecules with a double bond - Tans-Fats: A double bonded fat that remains flat > Fats in our bodies: "Flat logs are easier to stack than those with uneven lines/branches" > This could potentially lead to heart attacks There are several different nomenclatures used to denote the position of the pi bonds within the molecule: ### Glycerophospholipids glycerol backbone (three carbons & three -OH groups) triacylglycerols are none as being the least polar of the lipids - while the glycerol head is more polar than the nonpolar tails that are attached, the substituents of other lipid classes are often more polar in comparison (phosphates, carbohydrates, etc) ![[Pasted image 20231016072641.png]] ### Sphingolipids ![[Pasted image 20231015215348.png]] 1. Glycerol or Glycerol-3-phosphate - Triacylglycerols - Glycerophospholipids 2. Sphingolipids - Sphingosine (main backbone) - analogous to glycerol but one hydroxyl is replaced with amine group - Ceramide (amide instead of amine, potentially with another fatty acid residue?) - Sphingomyelin (amide instead of amine, phosphate on further hydroxyl group with various groups attached to phosphate) - Cerebroside (amide instead of amine, glycosidic bond to carbohydrate on further alcohol) - Ganglioside (like a cerebroside but more sugars and potential for branching acids?) 1. Steroids - Cholesterol (plays a large role in reducing rigidity of [[Biological Membrane]]) 2. Isoprenoids 3. Eicosanoids Exam 2 Review October 16th (7:30-8:50 pm) HS1 119 ### Steroids The main reason why steroids are classified as lipids is because they are also hydrophobic and insoluble in water Many steroids such as cholesterol contain a nonpolar tail, making it more in line with the traditional lipid/fatty acid molecules - I like to think of these as “chunky lipids” when they are found in the membrane as they function similarly to other phospholipids while its ## Energy Storage Why the hell is fat good at storing energy? Something about “energy on oxidation” - But how to the long nonpolar tails play into this ## Molecular Interactions ![[Pasted image 20231015222302.png]] emulsions micelles