Biological Molecules Flashcards
What are proteins?
Made of aa chains to form a polypeptide. Aa can be broken down and reassembled to make different proteins.
What are examples of food groups containing protein?
Animal products, fungi, nuts, seeds, legumes.
What are the functions of protein?
Energy, cellular components, hormones.
How are polypeptides formed?
Condensation polymerisation in an addition reaction.
Hydrolysis occurs in digestion.
How do amino acids act as a buffer?
H+ is highly reactive. In a basic solution, H+ lost from COOH so becomes more acidic.
In an acidic solution, H+ accepted by NH2 so becomes more basic.
Aa act as pH buffer to stabilise blood pH.
What are the different levels of protein structure?
Primary - aa sequence. Peptide bonds.
Secondary - how it folds locally. H bonds.
Tertiary - 3D shape of polypeptide. H bonds, hydrophobic interactions, disulfide bridges,
Quaternary - multiple polypeptides, prosthetic groups.
What is the difference between fibrous and globular proteins?
Fibrous: rod shaped, structural purposes, simple tertiary, cross links. Eg. Cytoskeleton, extra cellular matrix.
Globular: spherical, tertiary structures. Eg. Enzymes, receptors, hormones.
Define lipids.
Heterogeneous group of substances associated with living systems.
How to determine if it is omega 3, 6 or 9?
Count from the methyl end, where the first C=C is.
How is a triglyceride formed?
By a condensation reaction between glycerol and 3 fatty acid chains.
What are the 3 main types of lipid?
Fat - triglycerides. Fats and oils in diet.
Sterols - cholesterol. Membranes, myelin, bile.
Phospholipids - emulsifiers, lipid bilayer.
What are the functions of lipids?
- Structure - phospholipid, glycolipids, cholesterol, fatty acids.
- Storage - adipocytes in adipose tissue.
- Metabolism - essential fatty acids in cell membranes and organelles. Can alter membrane properties. Steroid and glucose metabolism impacted.
How are lipids transported?
Lipids associate with apolipoproteins which make it miscible in water. Each lipoprotein has a different physiological role.
What are the features of low density lipoproteins?
- from VLDL
- low amounts of TG
- highest amounts of cholesterol
- delivers cholesterol to peripheral tissues and back to liver
What are the features of high density lipoproteins?
- generated in liver and intestines
- very low levels of TG
- high amounts of cholesterol
- delivers cholesterol from peripheral tissues to liver for elimination
What is glucose needed for?
The normal function of the brain, kidneys, bone marrow, RBCs and reproductive tissues.
What are the main properties of glucose?
Can appear as components of other molecules, main source of energy in human diets, general formula CH2O, types differ by number and arrangement and availability of nutrients during digestion.
What are the roles of carbohydrates in the diet?
Energy for brain, muscles etc.
mono and disaccharides are soluble, provide volume in baked goods, brown at high temps, sweet taste.
Polysaccharides are used as thickening, texture modifiers etc.
Describe fructose.
Found in fruits, honey, some veg. Industrially derived in high fructose corn syrup. Cheap to make and more stable than sucrose.
Define glycosidic bond.
Type of covalent bond, water given off at carbons 1 and 4 in a condensation reaction.
What are oligosaccharides?
3-8 glucose units in plants, 9-10 in animal milk.
Component of fibre from plant tissues.
Fructo-oligosaccharides found in veg, galacto-oligosaccharides found in dairy products.
Prebiotic properties.
What are characteristics of polysaccharides.
Form very large molecules, synthesised by plants, animals, humans, stored for food, structural support or energy metabolism.
What are the 2 classes of polysaccharides?
- Starch - amylose, amylopectin.
- Non starch polysaccharides - indigestible.
What is starch?
Plant store of glucose and a major food reserve. Mixture of amylose and amylopectin.
