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Lipids: A generic term for fats and lipoids, the alcohol-ether-soluble constituents of protoplasm, which are insoluble in water. They comprise the fats, fatty oils, essential oils, waxes, phospholipids, glycolipids, sulfolipids, aminolipids, chromolipids (lipochromes), and fatty acids. (Grant & Hackh's Chemical Dictionary, 5th ed)

What are Lipids?

JoVE 10683

Lipids are a group of structurally and functionally diverse organic compounds that are insoluble in water. Certain classes of lipids, such as fats, phospholipids, and steroids are crucial to all living organisms. They function as structural components of cellular membranes, energy reservoirs, and signaling molecules.

Lipids are structurally and functionally diverse group of hydrocarbons. Hydrocarbons are chemical compounds that consist of carbon and hydrogen atoms. The carbon-carbon and carbon-hydrogen bonds are nonpolar, which means that the electrons between the atoms are shared equally. The individual nonpolar bonds impart an overall nonpolar characteristic to the hydrocarbon compound. Additionally, nonpolar compounds are hydrophobic, or “water-hating.” This means they do not form hydrogen bonds with water molecules, rendering them nearly insoluble in water. Depending on the chemical composition, lipids can be divided into different classes. The biologically important classes of lipids are fats, phospholipids, and steroids. The hydrocarbon backbone of fat has three carbon atoms. Each carbon carries a hydroxyl (–OH) group, making it glycerol. To form a fat, each of the hydroxyl groups of glycerol is linked to a fatty acid. A fatty acid is a long hydrocarbon chain with a carboxyl grou

 Core: Biology

Photoacoustic Tomography to Image Blood and Lipids in the Infrarenal Aorta

JoVE 10395

Source: Gurneet S. Sangha and Craig J. Goergen, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana


Photoacoustic tomography (PAT) is an emerging biomedical imaging modality that utilizes light generated acoustic waves to obtain compositional information from tissue. PAT can be used to image …

 Biomedical Engineering

Macromolecules- Concept

JoVE 10590

Biomolecules

Organisms contain a wide variety of organic molecules with numerous functions which depend on the chemical structures and properties of these molecules. All organic molecules contain a carbon backbone and hydrogen atoms. The carbon atom is central in the formation of a vast variety of organic molecules ranging in size, shape and complexity; inorganic molecules on the other…

 Lab Bio

Reconstitution of Membrane Proteins

JoVE 5693

Reconstitution is the process of returning an isolated biomolecule to its original form or function. This is particularly useful for studying membrane proteins, which enable important cellular functions and affect the behavior of nearby lipids. To study the function of purified membrane proteins in situ, they must be reconstituted by integrating them into an artificial lipid membrane.

 Biochemistry

An Overview of bGDGT Biomarker Analysis for Paleoclimatology

JoVE 10256

Source: Laboratory of Jeff Salacup - University of Massachusetts Amherst


Throughout this series of videos, natural samples were extracted and purified in search of organic compounds, called biomarkers, that can relate information on climates and environments of the past. One of the samples analyzed was sediment. Sediments accumulate…

 Earth Science

Lipid Digestion

JoVE 10832

Lipids are large molecules that are generally not water-soluble. Since most of the digestive enzymes in the human body are water-based, there are specific steps the body must take to break down lipids and make them available for use.

Lingual lipase is an enzyme secreted by the acinar cells of the sublingual gland that aids lipid digestion. Although found in saliva, it plays only a minimal role in breaking down lipids in the mouth. Interestingly, lingual lipase has a pH optimum of 3.5-6.0 and is not activated until chewed food enters the acidic environment of the stomach. Gastric lipase is an acidic lipase that is secreted by the gastric chief cells in the lining of the stomach. Lingual lipase and gastric lipase comprise the two acidic lipases found in the human digestive system. These lipases are active in the stomach but rapidly inactivated by bile acids in the duodenum. Together, gastric lipase and lingual lipase account for 10-30% of lipid hydrolysis that occurs in human adults, with gastric lipase contributing the most. Given the low concentrations of pancreatic lipase and bile salts in the neonatal phase, the acidic lipases are critical for lipid digestion and account for 50% of lipid hydrolysis in neonates. Bile contains bile salts, lecithin, and cholesterol-derived substances, so it acts as an emulsifier in the duodenum of the small i

 Core: Biology

Dietary Connections

JoVE 10746

Metabolic pathways are interconnected. The cellular respiration processes that convert glucose to ATP—such as glycolysis, pyruvate oxidation, and the citric acid cycle—tie into those that break down other organic compounds. As a result, various foods—from apples to cheese to guacamole—end up as ATP. In addition to carbohydrates, food also contains proteins and lipids—such as cholesterol and of these organic compounds are used as energy sources (i.e., to produce ATP). The human body possesses several enzymes that break down carbohydrates into simple sugars. While glucose can enter glycolysis directly, some simple sugars, such as fructose and galactose, are first converted into sugars that are intermediates of the glycolytic pathway. Proteins are broken down by enzymes into their constituent amino acids, which are usually recycled to create new proteins. However, if the body is starving or there is a surplus of amino acids, some amino acids can lose their amino groups and subsequently enter cellular respiration. The lost amino groups are converted into ammonia and incorporated into waste products. Different amino acids enter cellular respiration at different stages, including glycolysis, pyruvate oxidation, and the citric acid cycle. Amino acids can also be produced from intermediates in cellular respiration processes. Lipids, such as choleste

 Core: Biology
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