17: Lipids
- Page ID
- 15936
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)The lipids are a large and diverse group of naturally occurring organic compounds that are related by their solubility in nonpolar organic solvents (e.g., ether, chloroform, acetone and benzene) and general insolubility in water. There is great structural variety among the lipids, as will be demonstrated in the following sections.
- 17.0: Prelude to Lipids
- This page outlines the FDA's 2003 mandate requiring trans fatty acids to be listed on food labels due to health risks, effective January 1, 2006. It explains that trans fats, formed by turning liquid oils into solid fats, can elevate bad cholesterol levels. The chapter also covers the roles of fatty acids and lipids in energy provision and biological functions like energy storage and cell membrane structure.
- 17.1: Fatty Acids
- This page discusses fatty acids as carboxylic acids essential for lipid structure, classified into saturated and unsaturated types. It highlights the necessity of essential fatty acids like linoleic and α-linolenic, which must be acquired through diet. The page also covers the role of prostaglandins, derived from arachidonic acid, in physiology, and notes that waxes, esters of long-chain fatty acids, serve protective functions for plants and animals.
- 17.2: Fats and Oils
- This page discusses triglycerides, comprising three fatty acids and glycerol, differing in melting points and sources: saturated fats are animal-based and unsaturated oils are plant-based. It highlights the health concerns over saturated and trans fats from margarine and hydrogenated oils. Consumers are encouraged to use polyunsaturated oils and reduce fat intake.
- 17.3: Membranes and Membrane Lipids
- This page discusses the structure and function of cell membranes, emphasizing their lipid and protein composition. Membrane lipids, primarily phospholipids and sphingolipids, create a bilayer that provides fluidity and facilitates various cellular functions. Integral and peripheral proteins allow the transport of ions and molecules, while lipid diversity aids in cell recognition and communication.
- 17.4: Steroids
- This page discusses the importance of steroids, particularly cholesterol, in mammals, highlighting their roles in cell membranes and hormone synthesis while noting the health risks associated with high cholesterol levels. It also covers the production of bile acids and salts from cholesterol in the liver and their role in digestion.
- 17.E: Exercises
- This page discusses the melting points of fatty acids, highlighting stearic acid as the highest, followed by elaidic and oleic acids. It also notes that palmitelaidic acid has a lower melting point due to its shorter carbon chain. Additionally, it examines various oils in margarine, the roles of lecithin and cerebrosides, the diffusion of compounds through cell membranes, and the significance of steroid hormones and prostaglandins, particularly the LDL to HDL ratio.
- 17.S: Lipids (Summary)
- This page covers lipids, highlighting their solubility, biological roles, and various types including fatty acids and triglycerides. It discusses key reactions such as saponification and hydrogenation, as well as the dual properties of phospholipids in cell membranes and the crucial role of cholesterol in animals. The chapter emphasizes the significance of lipids in energy storage and cell structure, alongside their interactions within biological systems.