CARBOHYDRATES, LIPIDS & PROTEINS Topic 3.2 IB Biology Miss Werba

CARBS, LIPIDS & PROTEINS 3.5 TRANSCRIPTION & TRANSLATION TOPIC 3 - BIOCHEMISTRY 3.1 ELEMENTS & WATER 3.2 CARBS, LIPIDS & PROTEINS 3.3 DNA STRUCTURE 3.4 DNA REPLICATION 3.5 TRANSCRIPTION & TRANSLATION 3.6 ENZYMES 3.7 CELL RESPIRATION 3.8 PHOTOSYNTHESIS J WERBA – IB BIOLOGY 2

THINGS TO COVER Organic v Inorganic compounds Carbohydrates, Lipids & Proteins: Structure Types Examples Functions Energy storage J WERBA – IB BIOLOGY 3

ORGANIC and INORGANIC COMPOUNDS 3.2.1 ORGANIC and INORGANIC COMPOUNDS Organic compounds: based on carbon found in living things Exceptions: oxides of carbon (eg. CO2, CO) Anything else is inorganic! J WERBA – IB BIOLOGY 4

CONDENSATION AND HYDROLYSIS 3.2.5 CONDENSATION AND HYDROLYSIS Condensation reaction: Removing water from two monomers to form a dimer Hydrolysis reaction: Adding water can break polymers and dimers back into monomers J WERBA – IB BIOLOGY 5

CARBOHYDRATES: Examples (Command term = LIST) 3.2.3 CARBOHYDRATES: Examples (Command term = LIST) Remember: MONO = gives great flavour; DI = largely mid sized, POLY = can get stored Monosaccharides: Glucose, galactose, fructose Disaccharides: Lactose, maltose, sucrose Polysaccharides: Cellulose, glycogen, starch J WERBA – IB BIOLOGY 6

CARBOHYDRATES: Glucose and ribose 3.2.2 CARBOHYDRATES: Glucose and ribose Glucose Ribose C6H12O6 Formula C5H10O5 6 carbons  hexose sugar Carbons 5 carbons  pentose sugar J WERBA – IB BIOLOGY 7

CARBOHYDRATES: Condensation and hydrolysis 3.2.5 CARBOHYDRATES: Condensation and hydrolysis disaccharide monosaccharide maltose + maltose starch + water disaccharide polysaccharide J WERBA – IB BIOLOGY 8

CARBOHYDRATES: Functions (Command term = STATE) 3.2.4 CARBOHYDRATES: Functions (Command term = STATE) Animals: Glucose – energy via cell respiration Lactose – in milk; energy for infants Glycogen – short-term energy storage Chitin – in arthropod exoskeletons Deoxyribose – in DNA Plants: Fructose –in honey; good energy source Sucrose –used as a transport intermediate Cellulose –component of plant cell wall J WERBA – IB BIOLOGY 9

LIPIDS: Fatty acids General Saturated Unsaturated -COOH carboxyl group 3.2.2 LIPIDS: Fatty acids General Saturated Unsaturated -COOH carboxyl group -CH3 methyl group Contains no double bonds May contain double bonds J WERBA – IB BIOLOGY 10

LIPIDS: Functions (Command term = STATE) 3.2.6 LIPIDS: Functions (Command term = STATE) Remember: SHIPS  only need to learn 3 Structure: phospholipids in cell membranes Hormonal signalling: steroid hormones are lipids (eg. oestrogen, testosterone) Insulation: fat is an insulator; lipids also insulate neurons Protection: fats protect internal organs from damage Storage of energy: fats can be used as a long-term energy storage source J WERBA – IB BIOLOGY 11

LIPIDS: Condensation and hydrolysis 3.2.5 LIPIDS: Condensation and hydrolysis J WERBA – IB BIOLOGY 12

ENERGY STORAGE: Carbs vs lipids 3.2.7 ENERGY STORAGE: Carbs vs lipids Similarities: Polysaccharides and lipids contain a lot of chemical energy and can be used for energy storage Polysaccharides and lipids are both insoluble in water - they are not easily transported in the blood Carbohydrates and lipids both burn cleaner than proteins (they do not yield nitrogenous wastes) J WERBA – IB BIOLOGY 13

ENERGY STORAGE: Carbs vs lipids 3.2.7 ENERGY STORAGE: Carbs vs lipids Differences: Lipids contain more energy per gram than sugars Lipids are therefore lighter than sugars of equal yield Carbohydrates more readily digested (short-term) Lipids less readily digested (long-term storage) Mono/disaccharides are water soluble; lipids are not Sugars easier to transport in bloodstream to sites of use J WERBA – IB BIOLOGY 14

PROTEINS: Amino acids General a central carbon atom 4 side groups: 3.2.2 PROTEINS: Amino acids General a central carbon atom 4 side groups: the amine group (-NH2) the carboxylic acid group (-COOH) an H group the R group – R standing for “the rest” rather than an element J WERBA – IB BIOLOGY 15

PROTEINS: Condensation and hydrolysis 3.2.5 PROTEINS: Condensation and hydrolysis peptide bond J WERBA – IB BIOLOGY 16

Sample questions Q1. Which type of molecule is shown in the diagram below? J WERBA – IB BIOLOGY 17

Sample questions Q2. What is the difference between galactose and lactose? Lactose is a disaccharide and galactose is a monosaccharide. Lactose is the product of anaerobic respiration in humans and galactose is the product of anaerobic respiration in yeast. Lactose is an enzyme and galactose is a hormone. Galactose is a sugar found in milk but lactose is not found in milk. J WERBA – IB BIOLOGY 18

Sample questions A1. Peptide / protein A2. A - Lactose is a disaccharide and galactose is a monosaccharide. J WERBA – IB BIOLOGY 19

Sample questions Q3. Compare the use of carbohydrates and lipids in energy storage. (4 marks) J WERBA – IB BIOLOGY 20

Sample questions A3. both lipids and carbohydrates are primary sources of energy for organisms; lipids store more energy per unit mass/per gram than carbohydrates / lipids generally provide 2 to 3 times the energy of carbohydrates for a given mass; lipids provide 38 kJ g–1/ 9 C g–1 whereas carbohydrates have 17 kJ g–1/ 4 C g–1; carbohydrates are easier to transport (than lipids) making their energy more accessible; because lipids are insoluble (in water) whereas (small) carbohydrates are soluble (in water); carbohydrates are more easily taken out of storage making their energy more quickly available; carbohydrates are short-term storage molecules, whereas lipids provide long- term storage; J WERBA – IB BIOLOGY 21