Ch 2

• • Molecular biology explains living processes in terms of the chemical substances involved
• • Carbon atoms can form four covalent bonds allowing a diversity of stable compounds to exist.
• • Life is based on carbon compounds including carbohydrates, lipids, proteins and nucleic acids.
• • Metabolism is the web of all the enzyme-catalysed reactions in a cell or organism.
• • Anabolism is the synthesis of complex molecules from simpler molecules including the formation of macromolecules from monomers by condensation reactions.
• • Catabolism is the breakdown of complex molecules into simpler moleculesincluding the hydrolysis of macromolecules into monomers.
• • Application: Urea as an example of a compound that is produced by living organisms but can also be artificially synthesized.
• • Skill: Drawing molecular diagrams of glucose, ribose, a saturated fatty acid and a generalized amino acid.
• • Skill: Identification of biochemicals such as sugars, lipids or amino acids from molecular diagrams.
• • Application: Urea as an example of a compound that is produced by living organisms but can also be artificially synthesized.

  cyanic acid + ammonia -> Ammonium Cyanate (this salt is heated to artificially produce urea)

  Urea is a waste product of nitrogen metabolism and is eliminated by the kidneys in mammals
• • Water molecules are polar and hydrogen bonds form between them.
• • Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water.
• • Substances can be hydrophilic or hydrophobic
• • Application: Comparison of the thermal properties of water with those of methane

  water requires around 40 degrees due to hydrogen bonding methane only requires around 8 degrees
• • Application: Use of water as a coolant in sweat.

  water has a high specific heat capacity so can absorb a lot heat before vaporising
• Glucose, amino acids, cholesterol, fats, oxygen, and sodium chloride are transported in the blood in relation to their solubility in water
• NaCl is ionic, and its components Na+ and Cl- can be freely transported in the blood
• Most oxygen is transported by haemoglobin within red blood cells
• Amino acids are transported in the blood in an ionized state, where either the amine and/or carboxyl groups may be charged
• Lipids are non-polar and hydrophobic, so they do not dissolve in water; they form complexes with proteins (lipoproteins) to move through the bloodstream
• Hydrophilic portions of proteins, cholesterol, and phospholipids will face outwards and shield internal hydrophobic components
• The formation of glycosidic bonds and peptide bonds is condensation
• • Monosaccharide monomers are linked together by condensation reactions to form disaccharides and polysaccharide polymers.
• • Fatty acids can be saturated, monounsaturated or polyunsaturated
• • Unsaturated fatty acids can be cis or trans isomers
• • Triglycerides are formed by condensation from three fatty acids and one glycerol
• Cellulose is a structural polysaccharide of glucose units found in plants. It is a linear polysaccharide with the glucose units linked through β-1,4-glycosidic bonds
• • Low density lipoproteins (LDL) carry cholesterol from the liver to the rest of the body = BAD
  • High density lipoproteins (HDL) scavenge excess cholesterol and carry it back to the liver for disposal = GOOD
• Saturated and Trans fats increase LDL (low density lipoprotiens) this raises blood cholesterol levels which is BAD
• unsaturated CIS fats increase HDL (high density lipoprotiens) which lowers blood cholesterol levels which is GOOD
• • Application: Lipids are more suitable for long-term energy storage in humans than carbohydrates
• • Application: Evaluation of evidence and the methods used to obtain the evidence for health claims made about lipids.

  how strong is the correlation? are all relevant variables controlled? etc
• • Skill: Determination of body mass index by calculation or use of a nomogram

  read the middle intersection
• fructose + glucose = sucrose
• glucose + galactose = lactose
• glucose + glucose = maltose
• • Amino acids are linked together by condensation to form polypeptides
• • There are 20 different amino acids in polypeptides synthesized on ribosomes
• • Amino acids can be linked together in any sequence giving a huge range ofpossible polypeptides
• • The amino acid sequence of polypeptides is coded for by genes