Lipids Biology Notes PDF

Lipids Pg. 21 - 24  Why do humans Uses of Lipids like fatty foods? 1. Used to store long-term energy...

Lipids Pg. 21 - 24  Why do humans Uses of Lipids like fatty foods? 1. Used to store long-term energy ❑ Lipids store 2x more energy than carbohydrates/proteins 2. Cushion & protect vital organs (i.e. kidneys) 3. Major component of cell membranes 4. Used as hormones (chemical signals) 5. Insulate body against heat loss (i.e. whale blubber) 6. Provide water repelling coating for fur, feather, & leaves. Lipids Contain C, H and O and 2 functional groups – carboxyl and hydroxyl; different ratio composition than carbohydrates Lipids have more non-polar C-H bonds and few polar hydroxyl (O-H) bonds; ∴ hydrophobic Soluble in oils, insoluble in water Major types include: 1. Triglycerides/ fats 2. Phospholipids 3. Steroids 4. Waxes 1. Triglycerides/Fats Triglyceride is a lipid molecule made of a glycerol molecule + 3 fatty acids Fatty acid is a chain of usually 4 to 24 carbon atoms that have a carboxyl group on one end and a methyl group on the other. Typical fatty acid structure An example of a triglyceride structure Triglycerides/Fats con’t fatty acids are either ❑ Saturated = all carbon atoms hydrogen atoms on them; no double bonds btw C atoms; solid at room temp; from animals (i.e. red meat) ❑ Unsaturated = has 1 or more double bonds between carbon atoms, so they show bending (kink); liquid at room temp; found mono-unsaturated in most plants ? poly-unsaturated? cis vs. trans fat hydrogenation? Triglycerides / Fats cont’d Cis Fatty Acid – both hydrogens occur on the same as of a double bond. Trans Fatty acid – -hydrogens are on opposite sides of a double bond Triglycerides / Fats cont’d Cis fats maintain fluidity by creating bends preventing strong hydrophobic interactions ❑ Similar to the action cholesterol Trans fats (right) do not break down entirely and create strong hydrophobic interactions causing the membrane to become rigid. Prevents materials from crossing the membrane  Polyunsaturated Omega 3s EPA (eicosapentaenoic acid) – marine omega-3 found in fish DHA (docosahexaenoic acid). DHA is also a marine omega-3 found in fish ALA (alpha-linolenic acid). ALA is the form of omega-3 found in plants. ❑ Normal brain development & maintenance (DHA &EPA) ❑ Anti-inflammatory - promotes protectins (fatty acid metabolite that supports the immune system) (DHA & APA). ❑ Reduces blood clots and CVD risk ❑ Reduces overall inflammation Triglyceride Synthesis Three fatty acids bonded to glycerol by dehydration synthesis Ester Linkage Triglycerides or “neutral fat” Lipase (an enzyme) hydrolyzes (breakdown) fats. 2. Phospholipids Are main component of cell membrane are amphiphilic: have non polar (hydrophobic) “tails” and polar (hydrophilic) “head” Bilayer? 2. Phospholipids are amphiphilic: have non polar (hydrophobic) “tails” and polar (hydrophilic) “head” Watch: Phospholipids in water Phospholipids in COVID-19 3. Steroids all steroid are made of 4 linked carbon rings different steroids created by attaching different functional groups and location of double bonds e.g. of steroid = cholesterol, Estradiol testosterone, estrogen, estradiol (women) cholesterol  Steroids con’t Cholesterol ❑ required for proper nervous system function ❑ Important component of cell membranes helps keep cell membranes fluid & flexible ❑ too much of this bloodstream is linked to clogged arteries and risk of heart attack or stroke ❑ produced only by animals 85% naturally produced by our body only 15% derived from our diet  If cell membrane did not have cholesterol…. Cholesterol  Steroids con’t Cholesterol is a precursor to other steroids (i.e. cortisol, progesterone, estrogens, testosterone and bile acids) What a big difference a few atoms can make! Steroids con’t Eicosanoids Derived from arachidonic acid (a fatty acid) Function as chemical signals between cells Includes prostaglandins ❑ role in inflammation, blood clotting, hormone action, labor contractions, control of blood vessel diameter Side Effects of Excessive Steroids Use 4. Waxes are long fatty acid chains linked to alcohols or carbon rings Hydrophobic, firm consistency, pliable Produced by animals (i.e. earwax, beeswax), and plants (i.e. cutin) Cutin on leaves prevent Earwax protects the ear canal, assists infection and water loss lubrication, and provides some protection bacteria and water. None (contains at least 1 double Several double maximum # of H bond btw bonds atoms) carbons Straight kinks/ bends at kinks/ bends at the double bond the double bond chains solid liquid liquid animals plants plants NOT GOOD good BEST olive oil, vegetable oil, peanut butter, lard oil, canola oil LIPIDS DIAGRAMS Lipid Diagrams: Monomers Figure 1: Glycerol contains 3 carbons and 3 hydroxyl groups. Figure 2: Fatty acid molecules, long chains of C and H Double bond = kink Lipid Diagrams: Polymers Figure 3: Saturated Fat 1 glycerol + 3 fatty acid chains Solid at room temp “bad fat” Figure 4: Unsaturated Fat 1 glycerol + 3 fatty acid chains contains at least one double bond Liquid at room temp (oil) “good fat” Lipid Diagrams: Polymers Figure 5: Phospholipids contain a hydrophilic head and 2 fatty acid chains creating hydrophobic tails Figure 6: Steroids/sterols Made of 4 hydrocarbon rings; Include cholesterol and sex hormones (testosterone) Lipid Diagrams: Fatty Acid Chain