Understanding 3 and Skill 2:

• Carbohydrates, lipids, proteins, and nucleic acids are the four organic compound types found within living things

  • Carbohydrates: C, H, O. Ratio of 2H per O

  • Lipids: insoluble in water. Broad group, such as steroids, waxes, fatty acids, triglycerides (a fat or oil which has three fatty acids and a glycerol). Contain less oxygen than carbohydrates, such as oleic acid (an unsaturated fatty acid) C₁₈H₃₄O₂, or the steroid testosterone C₁₉H₂₈O₂

  • Proteins: chain(s) of amino acids. Often contains C, H, O, N, and some also contain S

  • Nucleic acids: chains of nucleotides, containing C, H, O, N, P. Two types are RNA and DNA

Skill 1:

• Drawing Ribose (C₅H₁₀O₅)

  • Oxygen on top of ring

  • 4 Carbons in ring and one forms side chain

  • Hydroxyl group points up on C1, down on C2+3

• Drawing Glucose (C₆H₁₂O₆)

  • 5 carbons in the ring and 1 forming side chain

  • In Alpha glucose, the hydroxyls are down on C 1,2,4 and up on C3

  • In Beta glucose, the hydroxyl is up on C1 and C3 and down on C2+4

  • In both Alpha and Beta, there is a hydroxyl on C 6 (so five in total on each)

• Drawing a saturated fatty acid

  • Carbons form an unbranched chain

  • Carbons bonded to each other through single bonds

  • Often between 14-20 carbons

  • There is a carboxyl group on one end

  • The other end is just hydrogen

  • All other carbons are bonded to two hydrogens

• Drawing amino acids

  • C in centre

  • An amine group

  • Carboxyl group

  • Hydrogen atom(s)

  • R group

Understanding 4:

• Metabolism is the sum of all reactions that occur in an organism

• Consists of pathways where one type of molecule is transformed into another. There are chains and cycles

Understanding 5:

• Anabolism is the synthesis of complex molecules from simpler molecules including the formation of macromolecules from monomers by condensation reactions.

• Examples

  • Protein synthesis using ribosomes

  • DNA synthesis during replication

  • Photosynthesis, production of glucose from CO₂ and water

  • Synthesis of complex carbs such as starch, cellulose, glycogen

Understanding 6:

• Catabolism is the breakdown of complex molecules into simpler molecules including the hydrolysis of macromolecules into monomers

• Examples:

  • Digestion of food

  • Cell respiration, oxidation of glucose and lipids into CO₂ and water

  • Digestion of complex carbon compounds in dead organic matter by decomposers

Topic 2.2 Water

Understandings

1. ➔ Water molecules are polar and hydrogen bonds form between them.

2. ➔ Hydrogen bonding and dipolarity explain the adhesive, cohesive, thermal and solvent properties of water.

3. ➔ Substances can be hydrophilic or hydrophobic

Nature of Science

1. ➔ Use theories to explain natural phenomena: the theory that hydrogen bonds form between water molecules explains water’s properties.

Applications

1. ➔ Comparison of the thermal properties of water with those of methane.

2. ➔ Use of water as a coolant in sweat.

3. ➔ Methods of transport of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in blood in relation to their solubility in water.

Understanding 1:

• In water, oxygen is slightly negative and hydrogen is slightly positive, so hydrogen bonds form between water molecules

• Hydrogen bonds are drawn in dotted lines between the negative O of one water molecule and positive H of another

Nature of Science 1:

• Hydrogen bonds are still a theory, but they explain the behaviours of water, such as its solvent, thermal, cohesive, and adhesive properties

Understanding 2:

• Cohesive properties

  • Cohesion refers to the binding together of two molecules of the same type

  • This is useful for water transport in plants: water is sucked through xylem vessels at low pressure

• Adhesive properties

  • Hydrogen bonds form between water molecules and other polar molecules, causing them to stick

  • Useful in leaves, where water adheres to cellulose in cell walls. If water evaporates from the cell walls, adhesive forces cause water to be drawn to the nearest xylem vessel

• Thermal properties:

  • High specific heat capacity

    • Hydrogen bonds restrict its motion and also cause more energy to be required to increase its motion (its temperature)

  • High latent heat of vaporization

    • Takes a lot of heat to vaporize and therefore is a good coolant

    • Hydrogen bonds need to be broken in order to vaporize it

  • High boiling point

    • its liquid state is in temps that most habitats on Earth have

• Solvent properties

  • Polar nature means in forms around charged or polar molecules (preventing them from clumping together), keeping them in solution

  • Water forms hydrogen bonds with polar molecules

  • Cytoplasm is where many substances are dissolved and its where many chemical reactions of metabolism occurs

Understanding 3:

• Polar molecules or compounds are hydrophilic

  • All substances that dissolve in water

  • All substances that water adheres to

  • All particles with positive or negative charges such as ions

• Nonpolar molecules are hydrophobic

  • All lipids, including fats and oils

Application 1:

• Methane is nonpolar, no hydrogen bonds

• Water is polar

Application 2:

• Why sweat cools your body:

  • The cooling is due to the body heat that is absorbed by the water (sweat).

  • The heat that is taken from your body is used to evaporate the water from your skin.

  • good example of the importance of high latent heat of vaporization.

Application 3:

• Sodium chloride is ionic, travels dissolved in blood plasma as ions Na⁺ and Cl^-

• Amino acids have both + and - charges, solubility depends on R group, but all amino acids are soluble enough to be carried dissolved in plasma

• Glucose is polar and freely soluble in water/blood plasma

• Oxygen is nonpolar but small enough for some to dissolve. Solubility decreases as temperature increases. Not enough can be dissolved to support aerobic cell respiration, so it binds to haemoglobin in red blood cells