Carbohydrates, Lipids and Cell Membranes Flashcards
Monosaccharide
Generally have molecular formulas that are some multiple of the unit CH2O. Sugars vary in the location of their carbonyl groups (C=O), the length of their carbon skeletons, and the spatial arrangement around asymmetric carbons.
Glucose (C6H12O6) is the most common monosaccharide.
The molecule has a carbonyl group (C=O) and multiple hydroxyl groups.
Disaccharide
Consists of two monosaccharides joined by a glycosidic linkage, a covalent bond formed between tow monosaccharides by a dehydration reaction.
Polysaccharide
Macromolecules, polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages.
Serve as energy storage (starch, glycogen), or structural roles (cellulose, chitin)
Starch
A plant polysaccharide. Plants store starch, a polymer of glucose monomers, as granules within cellular structures known as plastids, which include chloroplasts. Allows plant to stockpile surplus glucose as starch as stored energy.
Glycogen
An animal polysaccharide.
Animal cells stockpile glycogen as dense clusters of granules within liver and muscle cells.
Hydrolysis of glycogen releases glucose when the demand for sugar increases.
Cellulose
A structural polysaccharide of plant cell walls, consisting of glucose monomers joined by β glycosidic linkages
Chitin
A structural polysaccharide, consisting of amino sugar monomers, found in many fungal cell walls and in the exoskeletons of all arthropods
Lipids
Any group of large biological molecules, including fats, phospholipids, and steroids, that mix poorly, if at all with water.
Fat
A lipid consisting of three fatty acids linked to one glycerol molecule; also called a triacylglycerol or triglyceride
Fatty acid
A carboxylic acid with a long carbon chain. Fatty acids vary in length and in the number and location of double bonds; three fatty acids linked to a glycerol molecule form a fat molecule.
Saturated fat
A fat in which all carbons in the hydrocarbon tail are connected by single bonds, thus maximising the number of hydrogen atoms that are attached to the carbon skeleton
Unsaturated fat
A fat that has one or more double bonds between carbons in the hydrocarbon tail. This reduced the numbers of hydrogen atoms attached to the carbon skeleton
Phospholipid
A lipid made up of glycerol joined to two fatty acids and a phosphate group. The hydrocarbon tails of the fatty acids, act as nonpolar, hydrophobic tails, while the rest of the molecule acts as a polar, hydrophilic head.
Phospholipids form bilayers that function as biological membranes
Amphipathic
Having both a hydrophilic region and a hydrophobic region.
Fluid mosaic model
The cell membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids
Integral proteins
A membrane protein which penetrates the hydrophobic interior of the lipid bilayer. The majority are transmembrane proteins, which span the membrane; other integral proteins extend only partway into the hydrophobic interior.
Peripheral proteins
Membrane proteins that do not embedded in the lipid bilayer at all; they are appendages loosely bound to the surface of the membrane, often to exposed parts of integral proteins
Diffusion
The spontaneous movement of a substance down its concentration or electrochemical gradient, from a region where it is more concentrated to a region where it is less concentrated
Endocytosis
Cellular uptake of biological molecules and particulate matter vis formation of vesicles from the plasma membrane
Exocytosis
The cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane
Glycolipid
A lipid with one or more covalently attached carbohydrates
Glycoprotein
A protein with one or more covalently attached carbohydrates
