LipidsLipids

HydrophobicHydrophobic

Elements: C H OElements: C H O

Ratio of H:O= H greater than ORatio of H:O= H greater than O

CC5757HH110110OO66

CharacteristicsCharacteristics

Insoluble in water (they are non-polar)Insoluble in water (they are non-polar)Main Purpose: energy storage molecules Main Purpose: energy storage molecules (Fat)(Fat)

Can act as chemical messengers within Can act as chemical messengers within and between cellsand between cells

Focus will be on fats, phospholipids, and Focus will be on fats, phospholipids, and steroidssteroids

““Fats” -- TriglyceridesFats” -- Triglycerides

Made of two kinds of smaller molecules – Made of two kinds of smaller molecules – glycerol and fatty acids (one glycerol to glycerol and fatty acids (one glycerol to three fatty acids)three fatty acids)

Dehydration synthesis hooks these up – 3 Dehydration synthesis hooks these up – 3 waters produced for every one triglyceridewaters produced for every one triglyceride

glycerolFatty Acid Tails

Figure 5.10 The synthesis and structure of a fat, or triacylglycerolFigure 5.10 The synthesis and structure of a fat, or triacylglycerol

Figure 5.11 Examples of saturated and unsaturated fats and fatty acids Figure 5.11 Examples of saturated and unsaturated fats and fatty acids 

Fat vs. OilFat vs. Oil

Fats these are solid at room temperature – Fats these are solid at room temperature – Lard & Butter Lard & Butter

Plants and fish have unsaturated Plants and fish have unsaturated triglycerides, so are liquid at room temp – triglycerides, so are liquid at room temp – oiloil

Figure 5.11x Saturated and unsaturated fats and fatty acids: butter and oilFigure 5.11x Saturated and unsaturated fats and fatty acids: butter and oil

Are lipids “Bad?”Are lipids “Bad?”

Major function is energy storage Major function is energy storage

Ex. 1Ex. 1Gram of fat stores more than Gram of fat stores more than TWICETWICE the energy of a gram of the energy of a gram of polysaccaharidepolysaccaharide

Adipose tissue provides Adipose tissue provides cushioningcushioning for organs and for organs and insulationinsulation for body for body

SteroidsSteroids

Characterized by four fused carbon ringsCharacterized by four fused carbon rings

Cholesterol Cholesterol – found in cell membranes of – found in cell membranes of animalsanimals

Many hormones are steroids – sex Many hormones are steroids – sex hormoneshormones

Figure 5.14 Cholesterol, a steroid    Figure 5.14 Cholesterol, a steroid