SBI4U - Biochemistry

Macromolecules

Carbohydrates & Lipids

Organic Chemistry

• originally the chemistry of compounds produced by living organisms

• in general organic compounds contain carbon and hydrogen, and usually other elements such as nitrogen, sulfur and oxygen

Electronegativity

Homework, p.18 #9,8

• In a bond between nitrogen and hydrogen (N-H), which atom will the electrons be closer to? Explain your reasoning.

• How do polar covalent bonds and non-polar covalent bonds differ?

Homework, p.18 #10

• Oxygen plays a major role in biological molecules. Explain how oxygen plays a role in polarity, bond shape, (and redox reactions).

Polar vs. Non-Polar

• molecular polarity is determined by:– polarity of bonds within molecule– symmetry of molecular structure

• polarity of molecules or functional groups determines characteristics such as solubility

Homework, p.18 #6,7

• How can the atomic composition and shape of a molecule affect its polarity?

• What effect to the polarity, size, and shape of molecule have on the physical properties of the molecule?

• How do these factors affect intermolecular forces?

Homework, p.24 #1,5

• Water is a polar molecule. Explain how the polarity of water accounts for its lattice structure.

• How does polarity influence water’s role as a solvent?

H-bonding

Homework, p.18 #11

• In what ways do hydrogen bonds produce attractive forces between molecules? Include a labelled diagram to illustrate your answer.

• How do hydrogen bonds influence the physical properties of water?

Functional Groups

• specific clusters of atoms attached to the carbon backbone

• functional groups react in characteristic ways, giving chemical properties to macromolecules, and are involved in most reactions in living organisms

Functional Groups

Homework, p.28 #4

• Explain how functional groups influence solubility and the forces of attraction between molecules.

Macromolecules

• macromolecules are large molecules that are often composed of repeating sub-units

• some of the biologically important macromolecules are:– carbohydrates -lipids– proteins -nucleic acids

Carbohydrates

• carbohydrates are the most important energy source

• animals cannot synthesize carbohydrates; they must be consumed in plant material

Structure of Carbohydrates

• carbohydrates are made up of either single sugar molecules, or chains of many single sugar molecules– monosaccharides– disaccharides– oligosaccharides– polysaccharides

Monosaccharides

• single sugars in straight chain or ring form

• C:H:O usually in 1:2:1 ratio (glucose is C6H12O6)

• examples: fructose, galactose, ribose, deoxyribose

Monosaccharides

• some monosaccharides are isomers, e.g., glucose, fructose, and galactose

Disaccharides

• sugar molecules made from 2 single sugars

• formed by a dehydration synthesis (condensation) reaction

• See animation: http://www.youtube.com/watch?v=UyDnnD3fMaU

Find the sugars…

Polysaccharides

• oligosaccharides are shorter-chain sugars with 3-10 single sugars

• longer chain carbohydrates are called polysaccharides

• examples: starch, cellulose, glycogen, chitin

Polysaccharides

Lipids

• 4 groups:– fats & oils– phospholipids– steroids– waxes

• Functions:– energy storage– insulation– absorption of vitamins– raw materials

Triglycerides

• most common type of fat

• glycerol + 3 fatty acid molecules

• saturated and unsaturated fatty acid chains

• See animation: http://www.youtube.com/watch?v=3xF_LK9pnL0

Phospholipids

• key component of cell membranes

• 1 glycerol + 2 fatty acid chains + 1 phosphate group

• phosphate end is polar and water-soluble, fatty acid end is non-polar

Phospholipids

Steroids (Sterols)

• carbon-based multiple-ring structure

• used to make hormones such as estrogen and testosterone

Waxes

• long-chain fatty acids linked to alcohols/carbon rings

• suitable as water-proof coating for plant leaves, animal feathers, etc.