Week 8, Tuesday

BC I Week 8 Slides F 2024 pdf

In Fatty Acid labeling:

  • I.e. 18:3 △9 △12 △15

    • 18 is the number of carbons in the chain

    • 3 is the number of double bonds

    • △# is the location of the double bonds from the CO2 end

  • Can also be written ω3 ω6 ω9

    • The # is counting the double bonds from the opposite end of the CO2

Humans cannot create essential fatty acids

  • humans cannot introduce a carbon-carbon double bond beyond the △9 position

    • So, the acids Linoleic (△12) and Linoleic (△12 &15) must be provided by the diet

  • Arachidonic acid can be synthesized from Linoleic acid in humans

    • For this we look to the ω3 as the precursor for this synthesizing

    • These fatty acids are used for the synthesis of Eicosapentoenoic acid (EPA)

Unsaturated Fatty Acids:

  • Palmtoleic acid (ω7, 16:1△9)

  • Oleic acid (ω9, 18:1△9)

  • Linoleic acid (ω6, 18:2△9&12)

  • A-Linoleic acid (ω3, 18:3△9,12&15)

  • Arachidonic acid (ω6, 20:4△5,8,11&14)

  • Eicosapentaenoic acid (ω3, 20:5△5,8,11,14&17)

Triacyglycerols:

  • Saturated fats have boiling points higher than body temp

    • referred to as fats

  • Unsaturated fats have boiling points lower than body temp

    • Referred to as oils

Food labels:

  • fats have 9 calories per gram, typically

  • Rapeseed Oil (canola oil) has the lowest saturated fat %

  • Coconut oil has the highest saturated fat%

  • Fats are better to store as energy than carbohydrates

  • To store energy as carbohydrates would cause us to gain weight very quickly

  • The higher the saturated fat% in something, the more solid it will be

Transfats:

  • Triacyglycerols that have groups of trans fatty acids

Fatty acids are usually (mostly) Hydrophobic, but when there is a Phosphate group attached, that portion becomes Hydrophilic

  • i.e. Phosphatidic Acid

  • This is what creates the phospholipid bilayer in cell membranes

Sphingolipids:

  • Sphingosine is added to a fatty acid chain (typically has a NH group)

  • Common in cell and organelle membranes

Surfactant:

  • name given to fluid produced by alveoli

  • Fluid serves to lower the surface tension of the water that coats the surface of the alveoli

  • Major component of surfactant to phosphatidylacholine

    • In Amniotic fluid

    • Around 34-36 weeks, the amount of Phasphatidylacholine is much greater, which means the Sphingomyelin decreases

      • Resulting in Respiratory distress syndrome in Fetus due to the lack of surfactant

Cholesterol

  • Important for hormones (steroids), Vitamin D, and fatty acids

  • Cholesterol with a fatty acid= cholesteryl ester

Bile acids:

  • a water based solution, manufactured in the liver ad contains bile salts and unreacted cholesterol as solutes

  • Moved from the liver to the small intestine to function as an emulsifying agent as an aid to the digestion of dietary triacylglycerols

  • Most (>95%) of the bile components are reabsorbed from the intestinal lumen and recycled back to the liver via the hepatic portal vein

  • The liver produces 15-30g of bile per day and only about 0.5g is lost in the feces

  • Primary Bile Acids produced in the Liver:

    • Glycocholic Acid (1)

    • Taurocholic acid (2)

    • Glycochenodeoxycholic acid (3)

    • Taurochenodeoxyxholic acid (4)

  • Secondary Bile Acids produced in the Intestines:

    • 1 & 2 → Deoxycholic acid

    • 3 & 4 → Lithocholic acid

Through the body:

  • Dietary lipids enter mouth

    • CE, PL, TAG are unchanged

  • In the stomach and small intestines

    • Most of the CE, PL, TAG and some short and medium-chain fatty acids enter the small intestines

  • Bile salts emulsify, and pancreatic enzymes degrade dietary lipids

  • Primary products=

    • Free fatty acids

    • 2-monoacylglycerol

    • Cholesterol

  • Some is Reesterified into the lymph (chylomicrons) and the blood

  • The rest is remaining pieces of PL that leave the body through feces

Cholesterol products:

  • pregnenolone →

  • Progesterone →

    • Cortisol (a glucocorticoid)

    • Aldosterone (a mineralocoricoid)

    • Testosterone (an androgen) →

      • Estradiol (an estrogen)

Carbohydrates:

  • Simple sugars (monosaccharides) have the general formula: Cn(H2O)n

    • Glyceraldehyde

      • C3H6O3

    • Erythrose

      • C4H8O4

    • Ribose

      • C5H10O5

    • Glucose

      • C6H12O6

  • Each carbohydrate has many isomers (same formula but different structures)

    • I.e. C3H6O3

      • D-Glyceraldehyde

      • L-Glyceraldehyde

      • Dihydroxyacetone

    • Levatatory (left handed) isomers are naturally occurring in cells, and can be metabolized by cells.

    • Dextro-levatatory (right handed) isomers are not naturally occurring in the human body, and cannot be metabolized by cells

      • Resulting in Cell death

Other Variations in Carbohydrates:

  • D-Glucose

  • L-Glucose

  • D-Mannose

  • D-Galacotse

  • D-Fructose

    • All of those are Isomers

    • D-glucose and D-galactose are epimers

      • They differ at the fourth carbon (C-4)

    • D-glucose and D-mannose are epimers

      • They differ at the C-2

    • Glucose, mannose, and galactose are aidohexoses

    • Fructose is a ketohexose